@article{duc_azzi_zhang_kirkwood_white_trieu_riley_salter_chang_capnerhurst_et al._2023, title={Black Carbon Emissions, Transport and Effect on Radiation Forcing Modelling during the Summer 2019-2020 Wildfires in Southeast Australia}, volume={14}, ISSN={["2073-4433"]}, DOI={10.3390/atmos14040699}, abstractNote={The emission of black carbon (BC) particles, which cause atmospheric warming by affecting radiation budget in the atmosphere, is the result of an incomplete combustion process of organic materials. The recent wildfire event during the summer 2019–2020 in south-eastern Australia was unprecedented in scale. The wildfires lasted for nearly 3 months over large areas of the two most populated states of New South Wales and Victoria. This study on the emission and dispersion of BC emitted from the biomass burnings of the wildfires using the Weather Research Forecast–Chemistry (WRF–Chem) model aims to determine the extent of BC spatial dispersion and ground concentration distribution and the effect of BC on air quality and radiative transfer at the top of the atmosphere, the atmosphere and on the ground. The predicted aerosol concentration and AOD are compared with the observed data using the New South Wales Department of Planning and Environment (DPE) aethalometer and air quality network and remote sensing data. The BC concentration as predicted from the WRF–Chem model, is in general, less than the observed data as measured using the aethalometer monitoring network, but the spatial pattern corresponds well, and the correlation is relatively high. The total BC emission into the atmosphere during the event and the effect on radiation budget were also estimated. This study shows that the summer 2019–2020 wildfires affect not only the air quality and health impact on the east coast of Australia but also short-term weather in the region via aerosol interactions with radiation and clouds.}, number={4}, journal={ATMOSPHERE}, author={Duc, Hiep Nguyen and Azzi, Merched and Zhang, Yang and Kirkwood, John and White, Stephen and Trieu, Toan and Riley, Matthew and Salter, David and Chang, Lisa Tzu-Chi and Capnerhurst, Jordan and et al.}, year={2023}, month={Apr} }
 @article{jena_zhang_wang_campbell_2023, title={Decadal Application of WRF/Chem under Future Climate and Emission Scenarios: Impacts of Technology-Driven Climate and Emission Changes on Regional Meteorology and Air Quality}, volume={14}, ISSN={["2073-4433"]}, DOI={10.3390/atmos14020225}, abstractNote={This work presents new climate and emissions scenarios to investigate changes on future meteorology and air quality in the U.S. Here, we employ a dynamically downscaled Weather Research and Forecasting model coupled with chemistry (WRF/Chem) simulations that use two Intergovernmental Panel on Climate Change scenarios (i.e., A1B and B2) integrated with explicitly projected emissions from a novel Technology Driver Model (TDM). The projected 2046–2055 emissions show widespread reductions in most gas and aerosol species under both TDM/A1B and TDM/B2 scenarios over the U.S. The WRF/Chem simulations show that under the combined effects of the TDM/A1B climate and emission changes, the maximum daily average 8-h ozone (MDA8 h O3) increases by ~3 ppb across the U.S. mainly due to widespread increases in near-surface temperature and background methane concentrations, with some contributions from localized TDM emission changes near urban centers. For the TDM/B2 climate and emission changes, however, the MDA8 h O3 is widely decreased, except near urban centers where the relative TDM emission changes and O3 formation regimes leads to increased O3. The number of O3 exceedance days (i.e., MDA8 h O3 > 70 ppb) for the entire domain is significantly reduced by a grid cell maximum of up to 43 days (domain average ~0.5 days) and 62 days (domain average ~2 days) for the TDM/A1B and TDM/B2 scenarios, respectively, while in the western U.S., larger O3 increases lead to increases in nonattainment areas, especially for the TDM/A1B scenario. The combined effects of climate and emissions (for both A1B and B2 scenarios) will lead to widespread decreases in the daily 24-h average (DA24 h) PM2.5 concentrations, especially in the eastern U.S. (max decrease up to 93 µg m−3). The PM2.5 changes are dominated by decreases in anthropogenic emissions for both the TDM/A1B and TDM/B2 scenarios, with secondary effects on decreasing PM2.5 from climate change. The number of PM2.5 exceedance days (i.e., DA24 h PM2.5 > 35 µg m−3) is significantly reduced over the eastern U.S. under both TDM/A1B and B2 scenarios, which suggests that both climate and emission changes may synergistically lead to decreases in PM2.5 nonattainment areas in the future.}, number={2}, journal={ATMOSPHERE}, author={Jena, Chinmay and Zhang, Yang and Wang, Kai and Campbell, Patrick C.}, year={2023}, month={Feb} }
 @article{zhang_swinea_roskar_trackenberg_gittman_jarvis_kenworthy_yeager_fodrie_2022, title={Tropical cyclone impacts on seagrass-associated fishes in a temperate-subtropical estuary}, volume={17}, ISSN={["1932-6203"]}, DOI={10.1371/journal.pone.0273556}, abstractNote={Major storms can alter coastal ecosystems in several direct and indirect ways including habitat destruction, stormwater-related water quality degradation, and organism mortality. From 2010–2020, ten tropical cyclones impacted coastal North Carolina, providing an opportunity to explore ecosystem responses across multiple storms. Using monthly trawl and contemporaneous seagrass surveys conducted in Back Sound, NC, we evaluated how cyclones may affect the nursery role of shallow-water biogenic habitats by examining seagrass-associated fish responses within a temperate-subtropical estuary. We employed a general before-after-control-impact approach using trawls conducted prior (before) and subsequent (after) to storm arrival and years either without (control) or with (impact) storms. We examined whether effects were apparent over short (within ~three weeks of impact) and seasonal (May-October) timescales, as well as if the magnitude of storm-related shifts varied as a function of storm intensity. Our findings suggest that the ability of these shallow-water habitats to support juvenile fishes was not dramatically altered by hurricanes. The resilience exhibited by fishes was likely underpinned by the relative persistence of the seagrass habitat, which appeared principally undamaged by storms based upon review of available–albeit limited seagrass surveys. Increasing cyclone intensity, however, was correlated with greater declines in catch and may potentially underlie the emigration and return rate of fish after cyclones. Whether estuarine fishes will continue to be resilient to acute storm impacts despite chronic environmental degradation and predicted increases major tropical cyclone frequency and intensity remains a pressing question.}, number={10}, journal={PLOS ONE}, author={Zhang, Y. Stacy and Swinea, Savannah H. and Roskar, Grace and Trackenberg, Stacy N. and Gittman, Rachel K. and Jarvis, Jessie C. and Kenworthy, W. Judson and Yeager, Lauren A. and Fodrie, F. Joel}, year={2022}, month={Oct} }
 @article{guerette_chang_cope_duc_emmerson_monk_rayner_scorgie_silver_simmons_et al._2020, title={Evaluation of Regional Air Quality Models over Sydney, Australia: Part 2, Comparison of PM2.5 and Ozone}, volume={11}, ISSN={["2073-4433"]}, DOI={10.3390/atmos11030233}, abstractNote={Accurate air quality modelling is an essential tool, both for strategic assessment (regulation development for emission controls) and for short-term forecasting (enabling warnings to be issued to protect vulnerable members of society when the pollution levels are predicted to be high). Model intercomparison studies are a valuable support to this work, being useful for identifying any issues with air quality models, and benchmarking their performance against international standards, thereby increasing confidence in their predictions. This paper presents the results of a comparison study of six chemical transport models which have been used to simulate short-term hourly to 24 hourly concentrations of fine particulate matter less than and equal to 2.5 µm in diameter (PM2.5) and ozone (O3) for Sydney, Australia. Model performance was evaluated by comparison to air quality measurements made at 16 locations for O3 and 5 locations for PM2.5, during three time periods that coincided with major atmospheric composition measurement campaigns in the region. These major campaigns included daytime measurements of PM2.5 composition, and so model performance for particulate sulfate (SO42−), nitrate (NO3−), ammonium (NH4+) and elemental carbon (EC) was evaluated at one site per modelling period. Domain-wide performance of the models for hourly O3 was good, with models meeting benchmark criteria and reproducing the observed O3 production regime (based on the O3/NOx indicator) at 80% or more of the sites. Nevertheless, model performance was worse at high (and low) O3 percentiles. Domain-wide model performance for 24 h average PM2.5 was more variable, with a general tendency for the models to under-predict PM2.5 concentrations during the summer and over-predict PM2.5 concentrations in the autumn. The modelling intercomparison exercise has led to improvements in the implementation of these models for Sydney and has increased confidence in their skill at reproducing observed atmospheric composition.}, number={3}, journal={ATMOSPHERE}, author={Guerette, Elise-Andree and Chang, Lisa Tzu-Chi and Cope, Martin E. and Duc, Hiep N. and Emmerson, Kathryn M. and Monk, Khalia and Rayner, Peter J. and Scorgie, Yvonne and Silver, Jeremy D. and Simmons, Jack and et al.}, year={2020}, month={Mar} }
 @article{zhang_yang_gao_leung_bell_2020, title={Health and economic impacts of air pollution induced by weather extremes over the continental US}, volume={143}, ISSN={["1873-6750"]}, DOI={10.1016/j.envint.2020.105921}, abstractNote={Extreme weather events may enhance ozone (O3) and fine particulate matter (PM2.5) pollution, causing additional adverse health effects. This work aims to evaluate the health and associated economic impacts of changes in air quality induced by heat wave, stagnation, and compound extremes under the Representative Concentration Pathways (RCP) 4.5 and 8.5 climate scenarios. The Environmental Benefits Mapping and Analysis Program-Community Edition is applied to estimate health and related economic impacts of changes in surface O3 and PM2.5 levels due to heat wave, stagnation, and compound extremes over the continental U.S. during past (i.e., 2001–2010) and future (i.e., 2046–2055) decades under the two RCP scenarios. Under the past and future decades, the weather extremes-induced concentration increases may lead to several tens to hundreds O3-related deaths and several hundreds to over ten thousands PM2.5-related deaths annually. High mortalities and morbidities are estimated for populated urban areas with strong spatial heterogeneities. The estimated annual costs for these O3 and PM2.5 related health outcomes are $5.5–12.5 and $48.6–140.7 billion U.S. dollar for mortalities, and $8.9–97.8 and $19.5–112.5 million for morbidities, respectively. Of the extreme events, the estimated O3– and PM2.5–related mortality and morbidity attributed to stagnation are the highest, followed by heat wave or compound extremes. Large increases in heat wave and compound extreme events in the future decade dominate changes in mortality during these two extreme events, whereas population growth dominates changes in mortality during stagnation that is projected to occur less frequently. Projected reductions of anthropogenic emissions under both RCP scenarios compensate for the increased mortality due to increased occurrence for heat wave and compound extremes in the future. These results suggest a need to further reduce air pollutant emissions during weather extremes to minimize the adverse impacts of weather extremes on air quality and human health.}, journal={ENVIRONMENT INTERNATIONAL}, author={Zhang, Yang and Yang, Peilin and Gao, Yang and Leung, Ruby L. and Bell, Michelle L.}, year={2020}, month={Oct} }
 @article{itahashi_mathur_hogrefe_zhang_2020, title={Modeling stratospheric intrusion and trans-Pacific transport on tropospheric ozone using hemispheric CMAQ during April 2010-Part 1: Model evaluation and air mass characterization for stratosphere-troposphere transport}, volume={20}, ISSN={["1680-7324"]}, DOI={10.5194/acp-20-3373-2020}, abstractNote={Abstract. Stratospheric intrusion and trans-Pacific transport have been recognized as a
potential source of tropospheric ozone over the US. The
state-of-the-science Community Multiscale Air Quality (CMAQ) modeling system
has recently been extended for hemispheric-scale modeling applications
(referred to as H-CMAQ). In this study, H-CMAQ is applied to study the
stratospheric intrusion and trans-Pacific transport during April 2010. The
results will be presented in two companion papers. In this Part 1 paper,
model evaluation for tropospheric ozone (O3) is presented. Observations
at the surface, by ozonesondes and airplane, and by satellite across the
Northern Hemisphere are used to evaluate the model performance for O3.
H-CMAQ is able to capture surface and boundary layer (defined as surface to
750 hPa) O3 with a normalized mean bias (NMB) of −10 %; however, a
systematic underestimation with an NMB up to −30 % is found in the free
troposphere (defined as 750–250 hPa). In addition, a new air mass
characterization method is developed to distinguish influences of
stratosphere–troposphere transport (STT) from the effects of photochemistry
on O3 levels. This method is developed based on the ratio of O3
and an inert tracer indicating stratospheric O3 to examine the
importance of photochemistry, and sequential intrusion from upper layer.
During April 2010, on a monthly average basis, the relationship between
surface O3 mixing ratios and estimated stratospheric air masses in the
troposphere show a slight negative slope, indicating that high surface
O3 values are primarily affected by other factors (i.e., emissions),
whereas this relationship shows a slight positive slope at elevated sites,
indicating that STT has a possible impact at elevated sites. STT shows large
day-to-day variations, and STT impacts can either originate from the same
air mass over the entire US with an eastward movement found during early
April, or stem from different air masses at different locations indicated
during late April. Based on this newly established air mass characterization
technique, this study can contribute to understanding the role of STT and
also the implied importance of emissions leading to high surface O3.
Further research focused on emissions is discussed in a subsequent paper (Part 2).
                    }, number={6}, journal={ATMOSPHERIC CHEMISTRY AND PHYSICS}, author={Itahashi, Syuichi and Mathur, Rohit and Hogrefe, Christian and Zhang, Yang}, year={2020}, month={Mar}, pages={3373–3396} }
 @article{itahashi_mathur_hogrefe_napelenok_zhang_2020, title={Modeling stratospheric intrusion and trans-Pacific transport on tropospheric ozone using hemispheric CMAQ during April 2010-Part 2: Examination of emission impacts based on the higher-order decoupled direct method}, volume={20}, ISSN={["1680-7324"]}, DOI={10.5194/acp-20-3397-2020}, abstractNote={Abstract. The state-of-the-science Community Multiscale Air Quality (CMAQ) modeling
system, which has recently been extended for hemispheric-scale modeling
applications (referred to as H-CMAQ), is applied to study the trans-Pacific
transport, a phenomenon recognized as a potential source of air pollution in
the US, during April 2010. The results of this analysis are presented in
two parts. In the previous paper (Part 1), model evaluation for tropospheric
ozone (O3) was presented and an air mass characterization method was
developed. Results from applying this newly established method pointed to
the importance of emissions as the factor to enhance the surface O3 mixing
ratio over the US. In this subsequent paper (Part 2), emission impacts are
examined based on mathematically rigorous sensitivity analysis using the
higher-order decoupled direct method (HDDM) implemented in H-CMAQ. The HDDM
sensitivity coefficients indicate the presence of a NOx-sensitive
regime during April 2010 over most of the Northern Hemisphere. By defining
emission source regions over the US and east Asia, impacts from these
emission sources are examined. At the surface, during April 2010, the
emission impacts of the US and east Asia are comparable over the western
US with a magnitude of about 3 ppbv impacts on monthly mean O3
all-hour basis, whereas the impact of domestic emissions dominates over the
eastern US with a magnitude of about 10 ppbv impacts on monthly mean
O3. The positive correlation (r=0.63) between surface O3 mixing
ratios and domestic emission impacts is confirmed. In contrast, the
relationship between surface O3 mixing ratios and emission impacts from
east Asia exhibits a flat slope when considering the entire US. However,
this relationship has strong regional differences between the western and
eastern US; the western region exhibits a positive correlation
(r=0.36–0.38), whereas the latter exhibits a flat slope (r < 0.1).
Based on the comprehensive evaluation of H-CMAQ, we extend the sensitivity
analysis for O3 aloft. The results reveal the significant impacts of
emissions from east Asia on the free troposphere (defined as 750 to 250 hPa)
over the US (impacts of more than 5 ppbv) and the dominance of
stratospheric air mass on upper model layer (defined as 250 to 50 hPa) over
the US (impacts greater than 10 ppbv). Finally, we estimate changes of
trans-Pacific transport by taking into account recent emission trends from
2010 to 2015 assuming the same meteorological condition. The analysis
suggests that the impact of recent emission changes on changes in the
contribution of trans-Pacific transport to US O3 levels was
insignificant at the surface level and was small (less than 1 ppbv) over the free troposphere.
                    }, number={6}, journal={ATMOSPHERIC CHEMISTRY AND PHYSICS}, author={Itahashi, Syuichi and Mathur, Rohit and Hogrefe, Christian and Napelenok, Sergey L. and Zhang, Yang}, year={2020}, month={Mar}, pages={3397–3413} }
 @article{hong_zhang_zhang_davis_zhang_tong_guan_liu_he_2020, title={Weakening aerosol direct radiative effects mitigate climate penalty on Chinese air quality}, volume={10}, ISSN={["1758-6798"]}, DOI={10.1038/s41558-020-0840-y}, abstractNote={Future climate change may worsen air quality in many regions. However, evaluations of this ‘climate penalty’ on air quality have typically not assessed the radiative effects of changes in short-lived aerosols. Additionally, China’s clean air goals will decrease pollutant emissions and aerosol loadings, with concomitant weakening of aerosol feedbacks. Here we assess how such weakened aerosol direct effects alter the estimates of air pollution and premature mortality in China attributable to mid-century climate change under Representative Concentration Pathway 4.5. We found that weakening aerosol direct effects cause boundary layer changes that facilitate diffusion. This reduces air-pollution exposure (~4% in fine particulate matter) and deaths (13,800 people per year), which largely offset the additional deaths caused by greenhouse gas-dominated warming. These results highlight the benefits of reduced pollutant emissions through weakening aerosol direct effects and underline the potential of pollution control measures to mitigate climate penalties locked in by greenhouse gas emissions. Warming harms public health in Chinese cities directly via heat and indirectly by worsening air quality. Climate and epidemiological models estimate that reducing aerosols in a warmer climate can enhance atmospheric ventilation, reduce particulate matter exposure and offset warming-driven deaths.}, number={9}, journal={NATURE CLIMATE CHANGE}, author={Hong, Chaopeng and Zhang, Qiang and Zhang, Yang and Davis, Steven J. and Zhang, Xin and Tong, Dan and Guan, Dabo and Liu, Zhu and He, Kebin}, year={2020}, month={Sep}, pages={845-+} }
 @misc{paton-walsh_rayner_simmons_fiddes_schofield_bridgman_beaupark_broome_chambers_chang_et al._2019, title={A Clean Air Plan for Sydney: An Overview of the Special Issue on Air Quality in New South Wales}, volume={10}, ISSN={["2073-4433"]}, DOI={10.3390/atmos10120774}, abstractNote={This paper presents a summary of the key findings of the special issue of Atmosphere on Air Quality in New South Wales and discusses the implications of the work for policy makers and individuals. This special edition presents new air quality research in Australia undertaken by (or in association with) the Clean Air and Urban Landscapes hub, which is funded by the National Environmental Science Program on behalf of the Australian Government’s Department of the Environment and Energy. Air pollution in Australian cities is generally low, with typical concentrations of key pollutants at much lower levels than experienced in comparable cities in many other parts of the world. Australian cities do experience occasional exceedances in ozone and PM2.5 (above air pollution guidelines), as well as extreme pollution events, often as a result of bushfires, dust storms, or heatwaves. Even in the absence of extreme events, natural emissions play a significant role in influencing the Australian urban environment, due to the remoteness from large regional anthropogenic emission sources. By studying air quality in Australia, we can gain a greater understanding of the underlying atmospheric chemistry and health risks in less polluted atmospheric environments, and the health benefits of continued reduction in air pollution. These conditions may be representative of future air quality scenarios for parts of the Northern Hemisphere, as legislation and cleaner technologies reduce anthropogenic air pollution in European, American, and Asian cities. However, in many instances, current legislation regarding emissions in Australia is significantly more lax than in other developed countries, making Australia vulnerable to worsening air pollution in association with future population growth. The need to avoid complacency is highlighted by recent epidemiological research, reporting associations between air pollution and adverse health outcomes even at air pollutant concentrations that are lower than Australia’s national air quality standards. Improving air quality is expected to improve health outcomes at any pollution level, with specific benefits projected for reductions in long-term exposure to average PM2.5 concentrations.}, number={12}, journal={ATMOSPHERE}, author={Paton-Walsh, Clare and Rayner, Peter and Simmons, Jack and Fiddes, Sonya L. and Schofield, Robyn and Bridgman, Howard and Beaupark, Stephanie and Broome, Richard and Chambers, Scott D. and Chang, Lisa Tzu-Chi and et al.}, year={2019}, month={Dec} }
 @article{duan_caldwell_sun_mcnulty_zhang_shuster_liu_bolstad_2019, title={Data on projections of surface water withdrawal, consumption, and availability in the conterminous United States through the 21st century}, volume={23}, ISSN={2352-3409}, url={http://dx.doi.org/10.1016/J.DIB.2019.103786}, DOI={10.1016/j.dib.2019.103786}, abstractNote={We report data on the projections of annual surface water demand and supply in the conterminous United States at a high spatial resolution from 2010s to the end of the 21st century, including: 1) water withdrawal and consumption in the water-use sectors of domestic, thermoelectric power generation, and irrigation; 2) availability of surface water generated from local watershed runoff, accumulated from upstream areas, and artificially transferred from other basins. These data were derived from the projected changes in climate, population, energy structure, technology and water uses. These data are related to the original article “Understanding the role of regional water connectivity in mitigating climate change impacts on surface water supply stress in the United States” (Duan et al., 2019) [1].}, journal={Data in Brief}, publisher={Elsevier BV}, author={Duan, Kai and Caldwell, Peter V. and Sun, Ge and McNulty, Steven G. and Zhang, Yang and Shuster, Erik and Liu, Bingjun and Bolstad, Paul V.}, year={2019}, month={Apr}, pages={103786} }
 @article{monk_guerette_paton-walsh_silver_emmerson_utembe_zhang_griffiths_chang_duc_et al._2019, title={Evaluation of Regional Air Quality Models over Sydney and Australia: Part 1-Meteorological Model Comparison}, volume={10}, ISSN={["2073-4433"]}, DOI={10.3390/atmos10070374}, abstractNote={The ability of meteorological models to accurately characterise regional meteorology plays a crucial role in the performance of photochemical simulations of air pollution. As part of the research funded by the Australian government’s Department of the Environment Clean Air and Urban Landscape hub, this study set out to complete an intercomparison of air quality models over the Sydney region. This intercomparison would test existing modelling capabilities, identify any problems and provide the necessary validation of models in the region. The first component of the intercomparison study was to assess the ability of the models to reproduce meteorological observations, since it is a significant driver of air quality. To evaluate the meteorological component of these air quality modelling systems, seven different simulations based on varying configurations of inputs, integrations and physical parameterizations of two meteorological models (the Weather Research and Forecasting (WRF) and Conformal Cubic Atmospheric Model (CCAM)) were examined. The modelling was conducted for three periods coinciding with comprehensive air quality measurement campaigns (the Sydney Particle Studies (SPS) 1 and 2 and the Measurement of Urban, Marine and Biogenic Air (MUMBA)). The analysis focuses on meteorological variables (temperature, mixing ratio of water, wind (via wind speed and zonal wind components), precipitation and planetary boundary layer height), that are relevant to air quality. The surface meteorology simulations were evaluated against observations from seven Bureau of Meteorology (BoM) Automatic Weather Stations through composite diurnal plots, Taylor plots and paired mean bias plots. Simulated vertical profiles of temperature, mixing ratio of water and wind (via wind speed and zonal wind components) were assessed through comparison with radiosonde data from the Sydney Airport BoM site. The statistical comparisons with observations identified systematic overestimations of wind speeds that were more pronounced overnight. The temperature was well simulated, with biases generally between ±2 °C and the largest biases seen overnight (up to 4 °C). The models tend to have a drier lower atmosphere than observed, implying that better representations of soil moisture and surface moisture fluxes would improve the subsequent air quality simulations. On average the models captured local-scale meteorological features, like the sea breeze, which is a critical feature driving ozone formation in the Sydney Basin. The overall performance and model biases were generally within the recommended benchmark values (e.g., ±1 °C mean bias in temperature, ±1 g/kg mean bias of water vapour mixing ratio and ±1.5 m s−1 mean bias of wind speed) except at either end of the scale, where the bias tends to be larger. The model biases reported here are similar to those seen in other model intercomparisons.}, number={7}, journal={ATMOSPHERE}, author={Monk, Khalia and Guerette, Elise-Andree and Paton-Walsh, Clare and Silver, Jeremy D. and Emmerson, Kathryn M. and Utembe, Steven R. and Zhang, Yang and Griffiths, Alan D. and Chang, Lisa T. -C. and Duc, Hiep N. and et al.}, year={2019}, month={Jul} }
 @article{yang_zhang_wang_doraiswamy_cho_2019, title={Health impacts and cost-benefit analyses of surface O-3 and PM2.5 over the US under future climate and emission scenarios}, volume={178}, ISSN={["1096-0953"]}, DOI={10.1016/j.envres.2019.108687}, abstractNote={Health impacts of surface ozone (O3) and fine particulate matter (PM2.5) are of major concern worldwide. In this work, the Environmental Benefits Mapping and Analysis Program tool is applied to estimate the health and economic impacts of projected changes in O3 and PM2.5 in the U.S. in future (2046–2055) decade relative to current (2001–2010) decade under the Representative Concentration Pathway (RCP) 4.5 and 8.5 climate scenarios. Future annual-mean O3 reductions under RCP 4.5 prevent ~1,800 all-cause mortality, 761 respiratory hospital admissions (HA), and ~1.2 million school loss days annually, and result in economic benefits of ~16 billion, 29 million, and 132 million U.S. dollars (USD), respectively. By contrast, the projected future annual-mean O3 increases under RCP8.5 cause ~2,400 mortality, 941 respiratory HA, and ~1.6 million school loss days annually and result in economic disbenefits of ~21 billion, 36 million, and 175 million USD, respectively. Health benefits of reduced O3 double under RCP4.5 and health dis-benefits of increased O3 increase by 1.5 times under RCP8.5 in future with 2050 population and baseline incidence rate. Because of the reduction in projected future PM2.5 over CONUS under both scenarios, the annual avoided all-cause deaths, cardiovascular HA, respiratory HA, and work loss days are ~63,000 and ~83,000, ~5,300 and ~7,000, ~12,000 and ~15,000, and ~7.8 million and ~10 million, respectively, leading to economic benefits of ~560 and ~740 billion, ~240 and ~320 million, ~450 and ~590 million, and ~1,400 and ~1,900 million USD for RCP4.5 and 8.5, respectively. Health benefits of reduced PM2.5 for future almost double under both scenarios with the largest benefits in urban areas. RCP8.5 projects larger health and economic benefits due to a greater reduction in PM2.5 but with a warmer atmosphere and higher O3 pollution than RCP4.5. RCP4.5 leads to multiple-benefit goals including reduced O3 and PM2.5, reduced mortality and morbidity, and saved costs. Greater reduction in future PM2.5 under RCP4.5 should be considered to achieve larger multi-benefits.}, journal={ENVIRONMENTAL RESEARCH}, author={Yang, Peilin and Zhang, Yang and Wang, Kai and Doraiswamy, Prakash and Cho, Seung-Hyun}, year={2019}, month={Nov} }
 @article{hong_zhang_zhang_davis_tong_zheng_liu_guan_he_schellnhuber_2019, title={Impacts of climate change on future air quality and human health in China}, volume={116}, ISSN={["0027-8424"]}, DOI={10.1073/pnas.1812881116}, abstractNote={Significance}, number={35}, journal={PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA}, author={Hong, Chaopeng and Zhang, Qiang and Zhang, Yang and Davis, Steven J. and Tong, Dan and Zheng, Yixuan and Liu, Zhu and Guan, Dabo and He, Kebin and Schellnhuber, Hans Joachim}, year={2019}, month={Aug}, pages={17193–17200} }
 @article{zhang_jena_wang_paton-walsh_guerette_utembe_silver_keywood_2019, title={Multiscale Applications of Two Online-Coupled Meteorology-Chemistry Models during Recent Field Campaigns in Australia, Part I: Model Description and WRF/Chem-ROMS Evaluation Using Surface and Satellite Data and Sensitivity to Spatial Grid Resolutions}, volume={10}, ISSN={["2073-4433"]}, DOI={10.3390/atmos10040189}, abstractNote={Air pollution and associated human exposure are important research areas in Greater Sydney, Australia. Several field campaigns were conducted to characterize the pollution sources and their impacts on ambient air quality including the Sydney Particle Study Stages 1 and 2 (SPS1 and SPS2), and the Measurements of Urban, Marine, and Biogenic Air (MUMBA). In this work, the Weather Research and Forecasting model with chemistry (WRF/Chem) and the coupled WRF/Chem with the Regional Ocean Model System (ROMS) (WRF/Chem-ROMS) are applied during these field campaigns to assess the models’ capability in reproducing atmospheric observations. The model simulations are performed over quadruple-nested domains at grid resolutions of 81-, 27-, 9-, and 3-km over Australia, an area in southeastern Australia, an area in New South Wales, and the Greater Sydney area, respectively. A comprehensive model evaluation is conducted using surface observations from these field campaigns, satellite retrievals, and other data. This paper evaluates the performance of WRF/Chem-ROMS and its sensitivity to spatial grid resolutions. The model generally performs well at 3-, 9-, and 27-km resolutions for sea-surface temperature and boundary layer meteorology in terms of performance statistics, seasonality, and daily variation. Moderate biases occur for temperature at 2-m and wind speed at 10-m in the mornings and evenings due to the inaccurate representation of the nocturnal boundary layer and surface heat fluxes. Larger underpredictions occur for total precipitation due to the limitations of the cloud microphysics scheme or cumulus parameterization. The model performs well at 3-, 9-, and 27-km resolutions for surface O3 in terms of statistics, spatial distributions, and diurnal and daily variations. The model underpredicts PM2.5 and PM10 during SPS1 and MUMBA but overpredicts PM2.5 and underpredicts PM10 during SPS2. These biases are attributed to inaccurate meteorology, precursor emissions, insufficient SO2 conversion to sulfate, inadequate dispersion at finer grid resolutions, and underprediction in secondary organic aerosol. The model gives moderate biases for net shortwave radiation and cloud condensation nuclei but large biases for other radiative and cloud variables. The performance of aerosol optical depth and latent/sensible heat flux varies for different simulation periods. Among all variables evaluated, wind speed at 10-m, precipitation, surface concentrations of CO, NO, NO2, SO2, O3, PM2.5, and PM10, aerosol optical depth, cloud optical thickness, cloud condensation nuclei, and column NO2 show moderate-to-strong sensitivity to spatial grid resolutions. The use of finer grid resolutions (3- or 9-km) can generally improve the performance for those variables. While the performance for most of these variables is consistent with that over the U.S. and East Asia, several differences along with future work are identified to pinpoint reasons for such differences.}, number={4}, journal={ATMOSPHERE}, author={Zhang, Yang and Jena, Chinmay and Wang, Kai and Paton-Walsh, Clare and Guerette, Elise-Andree and Utembe, Steven and Silver, Jeremy David and Keywood, Melita}, year={2019}, month={Apr} }
 @article{zhang_wang_jena_paton-walsh_guerette_utembe_silver_keywood_2019, title={Multiscale Applications of Two Online-Coupled Meteorology-Chemistry Models during Recent Field Campaigns in Australia, Part II: Comparison of WRF/Chem and WRF/Chem-ROMS and Impacts of Air-Sea Interactions and Boundary Conditions}, volume={10}, ISSN={["2073-4433"]}, DOI={10.3390/atmos10040210}, abstractNote={Air-sea interactions play an important role in atmospheric circulation and boundary layer conditions through changing convection processes and surface heat fluxes, particularly in coastal areas. These changes can affect the concentrations, distributions, and lifetimes of atmospheric pollutants. In this Part II paper, the performance of the Weather Research and Forecasting model with chemistry (WRF/Chem) and the coupled WRF/Chem with the Regional Ocean Model System (ROMS) (WRF/Chem-ROMS) are intercompared for their applications over quadruple-nested domains in Australia during the three following field campaigns: The Sydney Particle Study Stages 1 and 2 (SPS1 and SPS2) and the Measurements of Urban, Marine, and Biogenic Air (MUMBA). The results are used to evaluate the impact of air-sea interaction representation in WRF/Chem-ROMS on model predictions. At 3, 9, and 27 km resolutions, compared to WRF/Chem, the explicit air-sea interactions in WRF/Chem-ROMS lead to substantial improvements in simulated sea-surface temperature (SST), latent heat fluxes (LHF), and sensible heat fluxes (SHF) over the ocean, in terms of statistics and spatial distributions, during all three field campaigns. The use of finer grid resolutions (3 or 9 km) effectively reduces the biases in these variables during SPS1 and SPS2 by WRF/Chem-ROMS, whereas it further increases these biases for WRF/Chem during all field campaigns. The large differences in SST, LHF, and SHF between the two models lead to different radiative, cloud, meteorological, and chemical predictions. WRF/Chem-ROMS generally performs better in terms of statistics and temporal variations for temperature and relative humidity at 2 m, wind speed and direction at 10 m, and precipitation. The percentage differences in simulated surface concentrations between the two models are mostly in the range of ±10% for CO, OH, and O3, ±25% for HCHO, ±30% for NO2, ±35% for H2O2, ±50% for SO2, ±60% for isoprene and terpenes, ±15% for PM2.5, and ±12% for PM10. WRF/Chem-ROMS at 3 km resolution slightly improves the statistical performance of many surface and column concentrations. WRF/Chem simulations with satellite-constrained boundary conditions (BCONs) improve the spatial distributions and magnitudes of column CO for all field campaigns and slightly improve those of the column NO2 for SPS1 and SPS2, column HCHO for SPS1 and MUMBA, and column O3 for SPS2 at 3 km over the Greater Sydney area. The satellite-constrained chemical BCONs reduce the model biases of surface CO, NO, and O3 predictions at 3 km for all field campaigns, surface PM2.5 predictions at 3 km for SPS1 and MUMBA, and surface PM10 predictions at all grid resolutions for all field campaigns. A more important role of chemical BCONs in the Southern Hemisphere, compared to that in the Northern Hemisphere reported in this work, indicates a crucial need in developing more realistic chemical BCONs for O3 in the relatively clean SH.}, number={4}, journal={ATMOSPHERE}, author={Zhang, Yang and Wang, Kai and Jena, Chinmay and Paton-Walsh, Clare and Guerette, Elise-Andree and Utembe, Steven and Silver, Jeremy David and Keywood, Melita}, year={2019}, month={Apr} }
 @article{chambers_guerette_monk_griffiths_zhang_duc_cope_emmerson_chang_silver_et al._2019, title={Skill-Testing Chemical Transport Models across Contrasting Atmospheric Mixing States Using Radon-222}, volume={10}, ISSN={["2073-4433"]}, DOI={10.3390/atmos10010025}, abstractNote={We propose a new technique to prepare statistically-robust benchmarking data for evaluating chemical transport model meteorology and air quality parameters within the urban boundary layer. The approach employs atmospheric class-typing, using nocturnal radon measurements to assign atmospheric mixing classes, and can be applied temporally (across the diurnal cycle), or spatially (to create angular distributions of pollutants as a top-down constraint on emissions inventories). In this study only a short (<1-month) campaign is used, but grouping of the relative mixing classes based on nocturnal mean radon concentrations can be adjusted according to dataset length (i.e., number of days per category), or desired range of within-class variability. Calculating hourly distributions of observed and simulated values across diurnal composites of each class-type helps to: (i) bridge the gap between scales of simulation and observation, (ii) represent the variability associated with spatial and temporal heterogeneity of sources and meteorology without being confused by it, and (iii) provide an objective way to group results over whole diurnal cycles that separates ‘natural complicating factors’ (synoptic non-stationarity, rainfall, mesoscale motions, extreme stability, etc.) from problems related to parameterizations, or between-model differences. We demonstrate the utility of this technique using output from a suite of seven contemporary regional forecast and chemical transport models. Meteorological model skill varied across the diurnal cycle for all models, with an additional dependence on the atmospheric mixing class that varied between models. From an air quality perspective, model skill regarding the duration and magnitude of morning and evening “rush hour” pollution events varied strongly as a function of mixing class. Model skill was typically the lowest when public exposure would have been the highest, which has important implications for assessing potential health risks in new and rapidly evolving urban regions, and also for prioritizing the areas of model improvement for future applications.}, number={1}, journal={ATMOSPHERE}, author={Chambers, Scott D. and Guerette, Elise-Andree and Monk, Khalia and Griffiths, Alan D. and Zhang, Yang and Duc, Hiep and Cope, Martin and Emmerson, Kathryn M. and Chang, Lisa T. and Silver, Jeremy D. and et al.}, year={2019}, month={Jan} }
 @article{duan_caldwell_sun_mcnulty_zhang_shuster_liu_bolstad_2019, title={Understanding the role of regional water connectivity in mitigating climate change impacts on surface water supply stress in the United States}, volume={570}, ISSN={["1879-2707"]}, DOI={10.1016/j.jhydrol.2019.01.011}, abstractNote={Surface water supply for a watershed relies on local water generated from precipitation and water connections with other watersheds. These connections are confined by topography and infrastructure, and respond diversely to stressors such as climate change, population growth, increasing energy and water demands. This study presents an integrative simulation and evaluation framework that incorporates the natural and anthropogenic water connections (i.e., stream flows, inter-basin water transfers, water withdrawals and return flows) among the 2099 8-digit Hydrologic Unit Code (HUC-8) watersheds across the conterminous United States. The framework is then applied to investigate the potential impacts of changes in climate and water use on regional water availability and water stress (the ratio of demand to supply). Our projections suggest that highly water-stressed areas may expand from 14% to 18% and the stressed population would increase from 19% to 24% by 2070–2099. Climate-change mitigation practices (e.g., energy structure reform, technology innovation) could largely offset these trends by reducing demand and enhancing supply. At the watershed scale, the spatially inhomogeneous responses to future changes suggest that regional water connectivity could significantly buffer the potential stress escalations due to the redistribution of water resources and diverse changes in consumptive uses and water supplies in different source areas. However, the detrimental future changes (e.g., depleting river discharges, larger demands of water withdrawal) may aggravate conflicts over water rights among regions and challenge our current water infrastructure system. This study provides new insights into the critical role of regional water connectivity in water supply security, and highlights the increasing need for integrated monitoring and management of water resources at various spatial levels in a changing world.}, journal={JOURNAL OF HYDROLOGY}, author={Duan, Kai and Caldwell, Peter V. and Sun, Ge and McNulty, Steven G. and Zhang, Yang and Shuster, Erik and Liu, Bingjun and Bolstad, Paul V.}, year={2019}, month={Mar}, pages={80–95} }
 @article{goldberg_gupta_wang_jena_zhang_lu_streets_2019, title={Using gap-filled MAIAC AOD and WRF-Chem to estimate daily PM2.5 concentrations at 1 km resolution in the Eastern United States}, volume={199}, ISSN={["1873-2844"]}, DOI={10.1016/j.atmosenv.2018.11.049}, abstractNote={To link short-term exposures of air pollutants to health outcomes, scientists must use high temporal and spatial resolution estimates of PM2.5 concentrations. In this work, we develop a daily PM2.5 product at 1 × 1 km2 spatial resolution across the eastern United States (east of 90° W) with the aid of 1 × 1 km2 MAIAC aerosol optical depth (AOD) data, 36 × 36 km2 WRF-Chem output, 1 × 1 km2 land-use type from the National Land Cover Database, and 0.125° × 0.125° ERA-Interim re-analysis meteorology. A gap-filling technique is applied to MAIAC AOD data to construct robust daily estimates of AOD when the satellite data are missing (e.g., areas obstructed by clouds or snow cover). The input data are incorporated into a multiple-linear regression model trained to surface observations of PM2.5 from the EPA Air Quality System (AQS) monitoring network. The model generates a high-fidelity estimate (r2 = 0.75 using a 10-fold random cross-validation) of daily PM2.5 throughout the eastern United States. Of the inputs to the statistical model, WRF-Chem output (r2 = 0.66) is the most important contributor to the skill of the model. MAIAC AOD is also a strong contributor (r2 = 0.52). Daily PM2.5 output from our statistical model can be easily integrated into county-level epidemiological studies. The novelty of this project is that we are able to simulate PM2.5 in a computationally efficient manner that is constrained to ground monitors, satellite data, and chemical transport model output at high spatial resolution (1 × 1 km2) without sacrificing the temporal resolution (daily) or spatial coverage (>2,000,000 km2).}, journal={ATMOSPHERIC ENVIRONMENT}, author={Goldberg, Daniel L. and Gupta, Pawan and Wang, Kai and Jena, Chinmay and Zhang, Yang and Lu, Zifeng and Streets, David G.}, year={2019}, month={Feb}, pages={443–452} }
 @article{wang_zhang_zhang_fan_leung_zheng_zhang_he_2018, title={Fine-scale application of WRF-CAM5 during a dust storm episode over East Asia: Sensitivity to grid resolutions and aerosol activation parameterizations}, volume={176}, ISSN={1352-2310}, url={http://dx.doi.org/10.1016/J.ATMOSENV.2017.12.014}, DOI={10.1016/J.ATMOSENV.2017.12.014}, abstractNote={An advanced online-coupled meteorology and chemistry model WRF-CAM5 has been applied to East Asia using triple-nested domains at different grid resolutions (i.e., 36-, 12-, and 4-km) to simulate a severe dust storm period in spring 2010. Analyses are performed to evaluate the model performance and investigate model sensitivity to different horizontal grid sizes and aerosol activation parameterizations and to examine aerosol-cloud interactions and their impacts on the air quality. A comprehensive model evaluation of the baseline simulations using the default Abdul-Razzak and Ghan (AG) aerosol activation scheme shows that the model can well predict major meteorological variables such as 2-m temperature (T2), water vapor mixing ratio (Q2), 10-m wind speed (WS10) and wind direction (WD10), and shortwave and longwave radiation across different resolutions with domain-average normalized mean biases typically within ±15%. The baseline simulations also show moderate biases for precipitation and moderate-to-large underpredictions for other major variables associated with aerosol-cloud interactions such as cloud droplet number concentration (CDNC), cloud optical thickness (COT), and cloud liquid water path (LWP) due to uncertainties or limitations in the aerosol-cloud treatments. The model performance is sensitive to grid resolutions, especially for surface meteorological variables such as T2, Q2, WS10, and WD10, with the performance generally improving at finer grid resolutions for those variables. Comparison of the sensitivity simulations with an alternative (i.e., the Fountoukis and Nenes (FN) series scheme) and the default (i.e., AG scheme) aerosol activation scheme shows that the former predicts larger values for cloud variables such as CDNC and COT across all grid resolutions and improves the overall domain-average model performance for many cloud/radiation variables and precipitation. Sensitivity simulations using the FN series scheme also have large impacts on radiations, T2, precipitation, and air quality (e.g., decreasing O3) through complex aerosol-radiation-cloud-chemistry feedbacks. The inclusion of adsorptive activation of dust particles in the FN series scheme has similar impacts on the meteorology and air quality but to lesser extent as compared to differences between the FN series and AG schemes. Compared to the overall differences between the FN series and AG schemes, impacts of adsorptive activation of dust particles can contribute significantly to the increase of total CDNC (∼45%) during dust storm events and indicate their importance in modulating regional climate over East Asia.}, journal={Atmospheric Environment}, publisher={Elsevier BV}, author={Wang, Kai and Zhang, Yang and Zhang, Xin and Fan, Jiwen and Leung, L. Ruby and Zheng, Bo and Zhang, Qiang and He, Kebin}, year={2018}, month={Mar}, pages={1–20} }
 @article{he_he_zhang_2018, title={Impacts of Air-sea Interactions on Regional Air Quality Predictions Using a Coupled Atmosphere-ocean Model in Southeastern US}, volume={18}, ISSN={["2071-1409"]}, DOI={10.4209/aaqr.2016.12.0570}, abstractNote={Air-sea interactions have significant impacts on coastal convection and surface fluxes exchange. They are important for the spatial and vertical distributions of air pollutants that affect public health, particularly in densely populated coastal areas. To understand the impacts of air-sea interactions on coastal air quality predictions, sensitivity simulations with different atmosphere-ocean coupling are conducted in this work over southeastern U.S. in July 2010 using the Weather Research and Forecasting Model with Chemistry (WRF/Chem). The results show that comparing to WRF/Chem without air-sea interactions, WRF/Chem with a 1-D ocean mixed layer model (WRF/Chem-OML) and WRF/Chem coupled with a 3-D Regional Ocean Modeling System (WRF/Chem-ROMS) predict the domain averaged changes in the sea surface temperature of 0.06°C and 0.94°C, respectively for July average. The simulated differences in the surface concentrations of O3 and PM2.5 between WRF/Chem-ROMS and WRF/Chem can be as large as 17.3 ppb and 7.9 µg m–3, respectively, with the largest changes occurring not only along coast and remote ocean, but also over some inland areas. Extensive validations against observations show that WRF/Chem-ROMS improves the predictions of most cloud and radiative variables, and surface concentrations of some chemical species such as SO2, NO2, maximum 1-h and 8-h O3, SO42–, NH4+, NO3–, and PM10. This illustrates the benefits and needs of using coupled atmosphere-ocean model with advanced model representations of air-sea interactions for regional air quality modeling.}, number={4}, journal={AEROSOL AND AIR QUALITY RESEARCH}, publisher={Taiwan Association for Aerosol Research}, author={He, Jian and He, Ruoying and Zhang, Yang}, year={2018}, month={Apr}, pages={1044–1067} }
 @article{campbell_zhang_yan_lu_streets_2018, title={Impacts of transportation sector emissions on future U.S. air quality in a changing climate. Part I: Projected emissions, simulation design, and model evaluation}, volume={238}, ISSN={0269-7491}, url={http://dx.doi.org/10.1016/J.ENVPOL.2018.04.020}, DOI={10.1016/J.ENVPOL.2018.04.020}, abstractNote={Emissions from the transportation sector are rapidly changing worldwide; however, the interplay of such emission changes in the face of climate change are not as well understood. This two-part study examines the impact of projected emissions from the U.S. transportation sector (Part I) on ambient air quality in the face of climate change (Part II). In Part I of this study, we describe the methodology and results of a novel Technology Driver Model (see graphical abstract) that includes 1) transportation emission projections (including on-road vehicles, non-road engines, aircraft, rail, and ship) derived from a dynamic technology model that accounts for various technology and policy options under an IPCC emission scenario, and 2) the configuration/evaluation of a dynamically downscaled Weather Research and Forecasting/Community Multiscale Air Quality modeling system. By 2046–2050, the annual domain-average transportation emissions of carbon monoxide (CO), nitrogen oxides (NOx), volatile organic compounds (VOCs), ammonia (NH3), and sulfur dioxide (SO2) are projected to decrease over the continental U.S. The decreases in gaseous emissions are mainly due to reduced emissions from on-road vehicles and non-road engines, which exhibit spatial and seasonal variations across the U.S. Although particulate matter (PM) emissions widely decrease, some areas in the U.S. experience relatively large increases due to increases in ship emissions. The on-road vehicle emissions dominate the emission changes for CO, NOx, VOC, and NH3, while emissions from both the on-road and non-road modes have strong contributions to PM and SO2 emission changes. The evaluation of the baseline 2005 WRF simulation indicates that annual biases are close to or within the acceptable criteria for meteorological performance in the literature, and there is an overall good agreement in the 2005 CMAQ simulations of chemical variables against both surface and satellite observations.}, journal={Environmental Pollution}, publisher={Elsevier BV}, author={Campbell, Patrick and Zhang, Yang and Yan, Fang and Lu, Zifeng and Streets, David}, year={2018}, month={Jul}, pages={903–917} }
 @article{campbell_zhang_yan_lu_streets_2018, title={Impacts of transportation sector emissions on future U.S. air quality in a changing climate. Part II: Air quality projections and the interplay between emissions and climate change}, volume={238}, ISSN={0269-7491}, url={http://dx.doi.org/10.1016/J.ENVPOL.2018.03.016}, DOI={10.1016/J.ENVPOL.2018.03.016}, abstractNote={In Part II of this work we present the results of the downscaled offline Weather Research and Forecasting/Community Multiscale Air Quality (WRF/CMAQ) model, included in the “Technology Driver Model” (TDM) approach to future U.S. air quality projections (2046–2050) compared to a current-year period (2001–2005), and the interplay between future emission and climate changes. By 2046–2050, there are widespread decreases in future concentrations of carbon monoxide (CO), nitrogen oxides (NOx = NO + NO2), volatile organic compounds (VOCs), ammonia (NH3), sulfur dioxide (SO2), and particulate matter with an aerodynamic diameter ≤ 2.5 μm (PM2.5) due mainly to decreasing on-road vehicle (ORV) emissions near urban centers as well as decreases in other transportation modes that include non-road engines (NRE). However, there are widespread increases in daily maximum 8-hr ozone (O3) across the U.S., which are due to enhanced greenhouse gases (GHG) including methane (CH4) and carbon dioxide (CO2) under the Intergovernmental Panel on Climate Change (IPCC) A1B scenario, and isolated areas of larger reduction in transportation emissions of NOx compared to that of VOCs over regions with VOC-limited O3 chemistry. Other notable future changes are reduced haze and improved visibility, increased primary organic to elemental carbon ratio, decreases in PM2.5 and its species, decreases and increases in dry deposition of SO2 and O3, respectively, and decreases in total nitrogen (TN) deposition. There is a tendency for transportation emission and CH4 changes to dominate the increases in O3, while climate change may either enhance or mitigate these increases in the west or east U.S., respectively. Climate change also decreases PM2.5 in the future. Other variable changes exhibit stronger susceptibility to either emission (e.g., CO, NOx, and TN deposition) or climate changes (e.g., VOC, NH3, SO2, and total sulfate deposition), which also have a strong dependence on season and specific U.S. regions.}, journal={Environmental Pollution}, publisher={Elsevier BV}, author={Campbell, Patrick and Zhang, Yang and Yan, Fang and Lu, Zifeng and Streets, David}, year={2018}, month={Jul}, pages={918–930} }
 @article{duan_sun_caldwell_mcnulty_zhang_2018, title={Implications of Upstream Flow Availability for Watershed Surface Water Supply across the Conterminous United States}, volume={54}, ISSN={["1752-1688"]}, DOI={10.1111/1752-1688.12644}, abstractNote={Abstract}, number={3}, journal={JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION}, author={Duan, Kai and Sun, Ge and Caldwell, Peter V. and McNulty, Steven G. and Zhang, Yang}, year={2018}, month={Jun}, pages={694–707} }
 @article{vara-vela_andrade_zhang_kumar_ynoue_souto-oliveira_silva lopes_landulfo_2018, title={Modeling of Atmospheric Aerosol Properties in the SAo Paulo Metropolitan Area: Impact of Biomass Burning}, volume={123}, ISSN={["2169-8996"]}, DOI={10.1029/2018JD028768}, abstractNote={Abstract}, number={17}, journal={JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES}, author={Vara-Vela, Angel and Andrade, Maria de Fatima and Zhang, Yang and Kumar, Prashant and Ynoue, Rita Yuri and Souto-Oliveira, Carlos Eduardo and Silva Lopes, Fabio Juliano and Landulfo, Eduardo}, year={2018}, month={Sep}, pages={9935–9956} }
 @misc{andrade_kumar_freitas_ynoue_martins_martins_nogueira_perez-martinez_miranda_albuquerque_et al._2017, title={Air quality in the megacity of Sao Paulo: Evolution over the last 30 years and future perspectives}, volume={159}, ISSN={["1873-2844"]}, DOI={10.1016/j.atmosenv.2017.03.051}, abstractNote={We present a comprehensive review of published results from the last 30 years regarding the sources and atmospheric characteristics of particles and ozone in the Metropolitan Area of São Paulo (MASP). During the last 30 years, many efforts have been made to describe the emissions sources and to analyse the primary and secondary formation of pollutants under a process of increasing urbanisation in the metropolitan area. From the occurrence of frequent violations of air quality standards in the 1970s and 1980s (due to the uncontrolled air pollution sources) to a substantial decrease in the concentrations of the primary pollutants, many regulations have been imposed and enforced, although those concentrations do not yet conform to the World Health Organization guidelines. The greatest challenge currently faced by the São Paulo State Environmental Protection Agency and the local community is controlling secondary pollutants such as ozone and fine particles. Understanding the formation of these secondary pollutants, by experimental or modelling approaches, requires the description of the atmospheric chemical processes driven by biofuel, ethanol and biodiesel emissions. Exposure to air pollution is the cause of many injuries to human health, according to many studies performed not only in the region but also worldwide, and affects susceptible populations such as children and the elderly. The MASP is the biggest megacity in the Southern Hemisphere, and its specifics are important for other urban areas that are facing the challenge of intensive growth that puts pressure on natural resources and worsens the living conditions in urban areas. This text discusses how imposing regulations on air quality and emission sources, mainly related to the transportation sector, has affected the evolution of pollutant concentrations in the MASP.}, journal={ATMOSPHERIC ENVIRONMENT}, author={Andrade, Maria de Fatima and Kumar, Prashant and Freitas, Edmilson Dias and Ynoue, Rita Yuri and Martins, Jorge and Martins, Leila D. and Nogueira, Thiago and Perez-Martinez, Pedro and Miranda, Regina Maura and Albuquerque, Taciana and et al.}, year={2017}, month={Jun}, pages={66–82} }
 @article{li_zhang_zhang_zhang_wang_zhang_li_zheng_geng_wallington_et al._2017, title={Attribution of PM2.5 exposure in Beijing-Tianjin-Hebei region to emissions: implication to control strategies}, volume={62}, ISSN={["2095-9281"]}, DOI={10.1016/j.scib.2017.06.005}, abstractNote={The Beijing-Tianjin-Hebei (BTH) region is one of the most heavily polluted regions in China, with both high PM2.5 concentrations and a high population density. A quantitative source-receptor relationship can provide valuable insights that can inform effective emission control strategies. Both source apportionment (SA) and source sensitivity (SS) can provide such information from different perspectives. In this study, both methods are applied in northern China to identify the most significant emission categories and source regions for PM2.5 exposure in BTH in 2013. Despite their differences, both models show similar distribution patterns for population and simulated PM2.5 concentrations, resulting in overall high PM2.5 exposure values (approximately 110μg/m3) and particularly high exposure values during the winter (approximately 200μg/m3). Both methods show that local emissions play a dominant role (70%), with some contribution from surrounding provinces (e.g., Shandong) via regional transport. The two methods also agree on the priority of local emission controls: both identify industrial, residential, and agricultural emissions as the top three categories that should be controlled locally. In addition, the effect of controlling agricultural ammonia emissions is approximately doubled when the co-benefits of reducing nitrate are considered. The synthesis of SA and SS for addressing specific categories of emissions provides a quantitative basis for the development of emission control strategies and policies for controlling PM2.5 in China.}, number={13}, journal={SCIENCE BULLETIN}, author={Li, Xin and Zhang, Qiang and Zhang, Yang and Zhang, Lin and Wang, Yuxuan and Zhang, Qianqian and Li, Meng and Zheng, Yixuan and Geng, Guannan and Wallington, Timothy J. and et al.}, year={2017}, month={Jul}, pages={957–964} }
 @article{yahya_wang_campbell_chen_glotfelty_he_pirhalla_zhang_2017, title={Decadal application of WRF/Chem for regional air quality and climate modeling over the US under the representative concentration pathways scenarios. Part 1: Model evaluation and impact of downscaling}, volume={152}, ISSN={["1873-2844"]}, DOI={10.1016/j.atmosenv.2016.12.029}, abstractNote={An advanced online-coupled meteorology-chemistry model, i.e., the Weather Research and Forecasting Model with Chemistry (WRF/Chem), is applied for current (2001–2010) and future (2046–2055) decades under the representative concentration pathways (RCP) 4.5 and 8.5 scenarios to examine changes in future climate, air quality, and their interactions. In this Part I paper, a comprehensive model evaluation is carried out for current decade to assess the performance of WRF/Chem and WRF under both scenarios and the benefits of downscaling the North Carolina State University's (NCSU) version of the Community Earth System Model (CESM_NCSU) using WRF/Chem. The evaluation of WRF/Chem shows an overall good performance for most meteorological and chemical variables on a decadal scale. Temperature at 2-m is overpredicted by WRF (by ∼0.2–0.3 °C) but underpredicted by WRF/Chem (by ∼0.3–0.4 °C), due to higher radiation from WRF. Both WRF and WRF/Chem show large overpredictions for precipitation, indicating limitations in their microphysics or convective parameterizations. WRF/Chem with prognostic chemical concentrations, however, performs much better than WRF with prescribed chemical concentrations for radiation variables, illustrating the benefit of predicting gases and aerosols and representing their feedbacks into meteorology in WRF/Chem. WRF/Chem performs much better than CESM_NCSU for most surface meteorological variables and O3 hourly mixing ratios. In addition, WRF/Chem better captures observed temporal and spatial variations than CESM_NCSU. CESM_NCSU performance for radiation variables is comparable to or better than WRF/Chem performance because of the model tuning in CESM_NCSU that is routinely made in global models.}, journal={ATMOSPHERIC ENVIRONMENT}, author={Yahya, Khairunnisa and Wang, Kai and Campbell, Patrick and Chen, Ying and Glotfelty, Timothy and He, Jian and Pirhalla, Michael and Zhang, Yang}, year={2017}, month={Mar}, pages={562–583} }
 @article{yahya_campbell_zhang_2017, title={Decadal application of WRF/chem for regional air quality and climate modeling over the US under the representative concentration pathways scenarios. Part 2: Current vs. future simulations}, volume={152}, ISSN={["1873-2844"]}, DOI={10.1016/j.atmosenv.2016.12.028}, abstractNote={Following a comprehensive model evaluation, this Part II paper presents projected changes in future (2046–2055) climate, air quality, and their interactions under the RCP4.5 and RCP8.5 scenarios using the Weather, Research and Forecasting model with Chemistry (WRF/Chem). In general, both WRF/Chem RCP4.5 and RCP8.5 simulations predict similar increases on average (∼2 °C) for 2-m temperature (T2) but different spatial distributions of the projected changes in T2, 2-m relative humidity, 10-m wind speed, precipitation, and planetary boundary layer height, due to differences in the spatial distributions of projected emissions, and their feedbacks into climate. Future O3 mixing ratios will decrease for most parts of the U.S. under the RCP4.5 scenario but increase for all areas under the RCP8.5 scenario due to higher projected temperature, greenhouse gas concentrations and biogenic volatile organic compounds (VOC) emissions, higher O3 values for boundary conditions, and disbenefit of NOx reduction and decreased NO titration over VOC-limited O3 chemistry regions. Future PM2.5 concentrations will decrease for both RCP4.5 and RCP8.5 scenarios with different trends in projected concentrations of individual PM species. Total cloud amounts decrease under both scenarios in the future due to decreases in PM and cloud droplet number concentration thus increased radiation. Those results illustrate the impacts of carbon policies with different degrees of emission reductions on future climate and air quality. The WRF/Chem and WRF simulations show different spatial patterns for projected changes in T2 for future decade, indicating different impacts of prognostic and prescribed gas/aerosol concentrations, respectively, on climate change.}, journal={ATMOSPHERIC ENVIRONMENT}, author={Yahya, Khairunnisa and Campbell, Patrick and Zhang, Yang}, year={2017}, month={Mar}, pages={584–604} }
 @article{campbell_zhang_wang_leung_fan_zheng_zhang_he_2017, title={Evaluation of a multi-scale WRF-CAM5 simulation during the 2010 East Asian Summer Monsoon}, volume={169}, ISSN={1352-2310}, url={http://dx.doi.org/10.1016/J.ATMOSENV.2017.09.008}, DOI={10.1016/J.ATMOSENV.2017.09.008}, abstractNote={The Weather Research and Forecasting model with Chemistry (WRF-Chem) with the physics package of the Community Atmosphere Model Version 5 (CAM5) has been applied at multiple scales over Eastern China (EC) and the Yangtze River Delta (YRD) to evaluate how increased horizontal resolution with physics designed for a coarser resolution climate model impacts aerosols and clouds, and the resulting precipitation characteristics and performance during the 2010 East Asian Summer Monsoon (EASM). Despite large underpredictions in surface aerosol concentrations and aerosol optical depth, there is good spatial agreement with surface observations of chemical predictions, and increasing spatial resolution tends to improve performance. Model bias and normalized root mean square values for precipitation predictions are relatively small, but there are significant differences when comparing modeled and observed probability density functions for precipitation in EC and YRD. Increasing model horizontal resolution tends to reduce model bias and error for precipitation predictions. The surface and column aerosol loading is maximized between about 32°N and 42°N in early to mid-May during the 2010 EASM, and then shifts north while decreasing in magnitude during July and August. Changing model resolution moderately changes the spatiotemporal relationships between aerosols, cloud properties, and precipitation during the EASM, thus demonstrating the importance of model grid resolution in simulating EASM circulation and rainfall patterns over EC and the YRD. Results from this work demonstrate the capability and limitations in the aerosol, cloud, and precipitation representation of WRF-CAM5 for regional-scale applications down to relatively fine horizontal resolutions. Further WRF-CAM5 model development and application in this area is needed.}, journal={Atmospheric Environment}, publisher={Elsevier BV}, author={Campbell, Patrick and Zhang, Yang and Wang, Kai and Leung, Ruby and Fan, Jiwen and Zheng, Bo and Zhang, Qiang and He, Kebin}, year={2017}, month={Nov}, pages={204–217} }
 @article{duan_sun_mcnulty_caldwell_cohen_sun_aldridge_zhou_zhang_zhang_2017, title={Future shift of the relative roles of precipitation and temperature in controlling annual runoff in the conterminous United States}, volume={21}, number={11}, journal={Hydrology and Earth System Sciences}, author={Duan, K. and Sun, G. and McNulty, S. G. and Caldwell, P. V. and Cohen, E. C. and Sun, S. L. and Aldridge, H. D. and Zhou, D. C. and Zhang, L. X. and Zhang, Y.}, year={2017}, pages={5517–5529} }
 @article{duan_sun_mcnulty_caldwell_cohen_sun_aldridge_zhou_zhang_zhang_2017, title={Future shift of the relative roles of precipitation and temperature in controlling annual runoff in the conterminous United States}, volume={21}, number={11}, journal={Hydrology and Earth System Sciences}, author={Duan, K. and Sun, G. and McNulty, S. G. and Caldwell, P. V. and Cohen, E. C. and Sun, S. L. and Aldridge, H. D. and Zhou, D. C. and Zhang, L. X. and Zhang, Y.}, year={2017}, pages={5517–5529} }
 @article{li_wang_guo_yu_mehmood_wang_liu_seinfeld_zhang_wong_et al._2017, title={High reduction of ozone and particulate matter during the 2016 G-20 summit in Hangzhou by forced emission controls of industry and traffic}, volume={15}, ISSN={["1610-3661"]}, DOI={10.1007/s10311-017-0642-2}, abstractNote={Many regions in China experience air pollution episodes because of the rapid urbanization and industrialization over the past decades. Here we analyzed the effect of emission controls implemented during the G-20 2016 Hangzhou summit on air quality. Emission controls included a forced closure of highly polluting industries, and limiting traffic and construction emissions in the cities and surroundings. Particles with aerodynamic diameter lower than 2.5 µm (PM2.5) and ozone (O3) were measured. We also simulated air quality using a forecast system consisting of the two-way coupled Weather Research and Forecast and Community Multi-scale Air Quality (WRF-CMAQ) model. Results show PM2.5 and ozone levels in Hangzhou during the G-20 Summit were considerably lower than previous to the G-20 Summit. The predicted concentrations of ozone were reduced by 25.4%, whereas the predicted concentrations of PM2.5 were reduced by 56%.}, number={4}, journal={ENVIRONMENTAL CHEMISTRY LETTERS}, author={Li, Pengfei and Wang, Liqiang and Guo, Ping and Yu, Shaocai and Mehmood, Khalid and Wang, Si and Liu, Weiping and Seinfeld, John H. and Zhang, Yang and Wong, David C. and et al.}, year={2017}, month={Dec}, pages={709–715} }
 @article{zhang_wang_jena_2017, title={Impact of Projected Emission and Climate Changes on Air Quality in the US: from National to State Level}, volume={110}, ISSN={["1877-0509"]}, DOI={10.1016/j.procs.2017.06.074}, abstractNote={Future ambient air quality will respond to changes in anthropogenic and biogenic emissions as well as climate changes, which may vary at national and state levels in different regions of the world. In this work, we applied an advanced online-coupled meteorology and chemistry model, the Weather Research and Forecasting Model with Chemistry (WRF/Chem), to the continental U.S. for current (2001-2010) and future (2046-2055) decades under four climate scenarios including the Representative Concentration Pathways (RCP) 4.5 and 8.5 and the Technology Driver Model (TDM) A1B and B2. Our goal is to quantify the impact of projected changes in anthropogenic and biogenic emissions and climate on future air quality under various climate scenarios for policy analysis for emission control and mitigation of adverse climate change. The simulations are performed at 36-, 12-km, and 4-km over North America, Continental U.S., and selected states, respectively. A comprehensive evaluation has been performed for the current simulation period using available observations from surface networks and satellites and shows an overall good performance in reproducing climatic and chemical observations at all grid scales. Future air quality features greater reduction in PM2.5 by RCP 4.5/8.5 than TDM B2/A1B and decreased O3 over most areas in the U.S. by RCP4.5 and TDM B2, indicating the benefits of carbon policy and technology changes with greater emission reductions. Air quality responds differently to projected changes in anthropogenic emissions in different states and seasons, indicating a need to develop state-specific emission control strategies for different seasons.}, journal={14TH INTERNATIONAL CONFERENCE ON MOBILE SYSTEMS AND PERVASIVE COMPUTING (MOBISPC 2017) / 12TH INTERNATIONAL CONFERENCE ON FUTURE NETWORKS AND COMMUNICATIONS (FNC 2017) / AFFILIATED WORKSHOPS}, author={Zhang, Yang and Wang, Kai and Jena, Chinmay}, year={2017}, pages={167–173} }
 @article{duan_sun_zhang_yahya_wang_madden_caldwell_cohen_mcnulty_2017, title={Impact of air pollution induced climate change on water availability and ecosystem productivity in the conterminous United States}, volume={140}, ISSN={0165-0009 1573-1480}, url={http://dx.doi.org/10.1007/S10584-016-1850-7}, DOI={10.1007/s10584-016-1850-7}, number={2}, journal={Climatic Change}, publisher={Springer Science and Business Media LLC}, author={Duan, Kai and Sun, Ge and Zhang, Yang and Yahya, Khairunnisa and Wang, Kai and Madden, James M. and Caldwell, Peter V. and Cohen, Erika C. and McNulty, Steven G.}, year={2017}, pages={259–272} }
 @article{glotfelty_zhang_2017, title={Impact of future climate policy scenarios on air quality and aerosol cloud interactions using an advanced version of CESM/CAM5: Part II. Future trend analysis and impacts of projected anthropogenic emissions}, volume={152}, ISSN={["1873-2844"]}, DOI={10.1016/j.atmosenv.2016.12.034}, abstractNote={Following a comprehensive evaluation of the Community Earth System Model modified at the North Carolina State University (CESM-NCSU), Part II describes the projected changes in the future state of the atmosphere under the representative concentration partway scenarios (RCP4.5 and 8.5) by 2100 for the 2050 time frame and examine the impact of climate change on future air quality under both scenarios, and the impact of projected emission changes under the RCP4.5 scenario on future climate through aerosol direct and indirect effects. Both the RCP4.5 and RCP8.5 simulations predict similar changes in air quality by the 2050 period due to declining emissions under both scenarios. The largest differences occur in O3, which decreases by global mean of 1.4 ppb under RCP4.5 but increases by global mean of 2.3 ppb under RCP8.5 due to differences in methane levels, and PM10, which decreases by global mean of 1.2 μg m−3 under RCP4.5 and increases by global mean of 0.2 μg m−3 under RCP8.5 due to differences in dust and sea-salt emissions under both scenarios. Enhancements in cloud formation in the Arctic and Southern Ocean and increases of aerosol optical depth (AOD) in central Africa and South Asia dominate the change in surface radiation in both scenarios, leading to global average dimming of 1.1 W m−2 and 2.0 W m−2 in the RCP4.5 and RCP8.5 scenarios, respectively. Declines in AOD, cloud formation, and cloud optical thickness from reductions of emissions of primary aerosols and aerosol precursors under RCP4.5 result in near surface warming of 0.2 °C from a global average increase of 0.7 W m−2 in surface downwelling solar radiation. This warming leads to a weakening of the Walker Circulation in the tropics, leading to significant changes in cloud and precipitation that mirror a shift in climate towards the negative phase of the El Nino Southern Oscillation.}, journal={ATMOSPHERIC ENVIRONMENT}, author={Glotfelty, Timothy and Zhang, Yang}, year={2017}, month={Mar}, pages={531–552} }
 @article{glotfelty_he_zhang_2017, title={Impact of future climate policy scenarios on air quality and aerosol-cloud interactions using an advanced version of CESM/CAM5: Part I. model evaluation for the current decadal simulations}, volume={152}, ISSN={["1873-2844"]}, DOI={10.1016/j.atmosenv.2016.12.035}, abstractNote={A version of the Community Earth System Model modified at the North Carolina State University (CESM-NCSU) is used to simulate the current and future atmosphere following the representative concentration partway scenarios for stabilization of radiative forcing at 4.5 W m−2 (RCP4.5) and radiative forcing of 8.5 W m−2 (RCP8.5). Part I describes the results from a comprehensive evaluation of current decadal simulations. Radiation and most meteorological variables are well simulated in CESM-NCSU. Cloud parameters are not as well simulated due in part to the tuning of model radiation and general biases in cloud variables common to all global chemistry-climate models. The concentrations of most inorganic aerosol species (i.e., SO42-, NH4+, and NO3−) are well simulated with normalized mean biases (NMBs) typically less than 20%. However, some notable exceptions are European NH4+, which is overpredicted by 33.0–42.2% due to high NH3 emissions and irreversible coarse mode condensation, and Cl−, that is negatively impacted by errors in emissions driven by wind speed and overpredicted HNO3. Carbonaceous aerosols are largely underpredicted following the RCP scenarios due to low emissions of black carbon, organic carbon, and anthropogenic volatile compounds in the RCP inventory and efficient wet removal. This results in underpredictions of PM2.5 and PM10 by 6.4–55.7%. The column mass abundances are reasonably well simulated. Larger biases occur in surface mixing ratios of trace gases in CESM-NCSU, likely due to numerical diffusion from the coarse grid spacing of the CESM-NCSU simulations or errors in the magnitudes and vertical structure of emissions. This is especially true for SO2 and NO2. The mixing ratio of O3 is overpredicted by 38.9–76.0% due to the limitations in the O3 deposition scheme used in CESM and insufficient titration resulted from large underpredictions in NO2. Despite these limitations, CESM-NCSU reproduces reasonably well the current atmosphere in terms of radiation, clouds, meteorology, trace gases, aerosols, and aerosol-cloud interactions, making it suitable for future climate simulations.}, journal={ATMOSPHERIC ENVIRONMENT}, author={Glotfelty, Timothy and He, Jian and Zhang, Yang}, year={2017}, month={Mar}, pages={222–239} }
 @article{glotfelty_he_zhang_2017, title={Improving organic aerosol treatments in CESM/CAM5: Development, application, and evaluation}, volume={9}, ISSN={["1942-2466"]}, DOI={10.1002/2016ms000874}, abstractNote={Abstract}, number={2}, journal={JOURNAL OF ADVANCES IN MODELING EARTH SYSTEMS}, author={Glotfelty, Timothy and He, Jian and Zhang, Yang}, year={2017}, month={Jun}, pages={1506–1539} }
 @article{yahya_glotfelty_wang_zhang_nenes_2017, title={Modeling regional air quality and climate: Improving organic aerosol and aerosol activation processes in WRF/Chem version 3.7.1}, volume={10}, number={6}, journal={Geoscientific Model Development}, author={Yahya, K. and Glotfelty, T. and Wang, K. and Zhang, Y. and Nenes, A.}, year={2017}, pages={2333–2363} }
 @article{he_zhang_wang_chen_leung_fan_li_zheng_zhang_duan_et al._2017, title={Multi-year application of WRF-CAM5 over East Asia-Part I: Comprehensive evaluation and formation regimes of O-3 and PM2.5}, volume={165}, ISSN={["1873-2844"]}, DOI={10.1016/j.atmosenv.2017.06.015}, abstractNote={Accurate simulations of air quality and climate require robust model parameterizations on regional and global scales. The Weather Research and Forecasting model with Chemistry version 3.4.1 has been coupled with physics packages from the Community Atmosphere Model version 5 (CAM5) (WRF-CAM5) to assess the robustness of the CAM5 physics package for regional modeling at higher grid resolutions than typical grid resolutions used in global modeling. In this two-part study, Part I describes the application and evaluation of WRF-CAM5 over East Asia at a horizontal resolution of 36-km for six years: 2001, 2005, 2006, 2008, 2010, and 2011. The simulations are evaluated comprehensively with a variety of datasets from surface networks, satellites, and aircraft. The results show that meteorology is relatively well simulated by WRF-CAM5. However, cloud variables are largely or moderately underpredicted, indicating uncertainties in the model treatments of dynamics, thermodynamics, and microphysics of clouds/ices as well as aerosol-cloud interactions. For chemical predictions, the tropospheric column abundances of CO, NO2, and O3 are well simulated, but those of SO2 and HCHO are moderately overpredicted, and the column HCHO/NO2 indicator is underpredicted. Large biases exist in the surface concentrations of CO, NOx, and PM10 due to uncertainties in the emissions as well as vertical mixing. The underpredictions of NO lead to insufficient O3 titration, thus O3 overpredictions. The model can generally reproduce the observed O3 and PM indicators. These indicators suggest to control NOx emissions throughout the year, and VOCs emissions in summer in big cities and in winter over North China Plain, North/South Korea, and Japan to reduce surface O3, and to control SO2, NH3, and NOx throughout the year to reduce inorganic surface PM.}, journal={ATMOSPHERIC ENVIRONMENT}, author={He, Jian and Zhang, Yang and Wang, Kai and Chen, Ying and Leung, L. Ruby and Fan, Jiwen and Li, Meng and Zheng, Bo and Zhang, Qiang and Duan, Fengkui and et al.}, year={2017}, month={Sep}, pages={122–142} }
 @article{zhang_wang_he_2017, title={Multi-year application of WRF-CAM5 over East Asia-Part II: Interannual variability, trend analysis, and aerosol indirect effects}, volume={165}, ISSN={["1873-2844"]}, DOI={10.1016/j.atmosenv.2017.06.029}, abstractNote={Following a comprehensive evaluation of WRF-CAM5 in Part I, Part II describes analyses of interannual variability, multi-year variation trends, and the direct, indirect, and total effects of anthropogenic aerosols. The interannual variations of chemical column and surface concentrations, and ozone (O3)/particulate matter (PM) indicators are strongly correlated to anthropogenic emission changes. Despite model biases, the model captures well the observed interannual variations of temperature at 2-m, cloud fraction, shortwave cloud forcing, downwelling shortwave radiation, cloud droplet number concentration, column O3, and column formaldehyde (HCHO) for the whole domain. While the model reproduces the volatile organic compound (VOC)-limited regimes of O3 chemistry at sites in Hong Kong, Taiwan, Japan, South Korea, and from the Acid Deposition Monitoring Network in East Asia (EANET) and the degree of sulfate neutralization at the EANET sites, it has limited capability in capturing the interannual variations of the ratio of O3 and nitrogen dioxide (O3/NO2) and PM chemical regime indicators, due to uncertainties in the emissions of precursors for O3 and secondary PM, the model assumption for ammonium bisulfate (NH4HSO4) as well as lack of gas/particle partitioning of total ammonia and total nitrate. While the variation trends in multi-year periods in aerosol optical depth and column concentrations of carbon monoxide, sulfur dioxide, and NO2 are mainly caused by anthropogenic emissions, those of major meteorological and cloud variables partly reflect feedbacks of chemistry to meteorological variables. The impacts of anthropogenic aerosol indirect effects either dominate or play an important role in the aerosol total effects for most cloud and chemical predictions, whereas anthropogenic aerosol direct effects influence most meteorological and radiation variables. The direct, indirect, and total effects of anthropogenic aerosols exhibit a strong interannual variability in 2001, 2006, and 2011.}, journal={ATMOSPHERIC ENVIRONMENT}, author={Zhang, Yang and Wang, Kai and He, Jian}, year={2017}, month={Sep}, pages={222–239} }
 @article{hong_zhang_zhang_tang_tong_he_2017, title={Multi-year downscaling application of two-way coupled WRF v3.4 and CMAQ v5.0.2 over east Asia for regional climate and air quality modeling: model evaluation and aerosol direct effects}, volume={10}, number={6}, journal={Geoscientific Model Development}, author={Hong, C. P. and Zhang, Q. and Zhang, Y. and Tang, Y. H. and Tong, D. and He, K. B.}, year={2017}, pages={2447–2470} }
 @article{saha_khlystov_yahya_zhang_xu_ng_grieshop_2017, title={Quantifying the volatility of organic aerosol in the southeastern US}, volume={17}, number={1}, journal={Atmospheric Chemistry and Physics}, author={Saha, P. K. and Khlystov, A. and Yahya, K. and Zhang, Y. and Xu, L. and Ng, N. L. and Grieshop, A. P.}, year={2017}, pages={501–520} }
 @article{song_wang_zhang_hong_zhou_2017, title={Simulation and evaluation of dust emissions with WRF-Chem (v3.7.1) and its relationship to the changing climate over East Asia from 1980 to 2015}, volume={167}, ISSN={["1873-2844"]}, DOI={10.1016/j.atmosenv.2017.08.051}, abstractNote={Dust particles have been long recognized to affect the atmospheric radiative balance and are influenced by climate change. Impacts of climate change on dust emissions in East Asia, however, are not well understood. In this work, we conduct an evaluation of meteorological variables and dust emissions using the Weather Research and Forecasting model coupled with chemistry (WRF-Chem) and examine the relationships between dust emissions and meteorological variables (wind speed, precipitation, and temperature) over East Asia during the period of 1980–2015. Model simulated surface meteorological variables compared well overall with surface-based observations, consistent with other WRF studies. Compared to observations, the coarse particulate matter (PM10-2.5) concentrations were underpredicted for most dust source regions of East Asia with a domain-wide mean bias and correlation of −40.2 μg m−3 and 0.5 against observations, respectively. Dust particulate concentrations simulated by WRF-Chem were found to reproduce the observed spatial variability in surface dust particulates over East Asia. The average annual dust emission (0 < r < 20 μm) is around 67.4 Tg yr−1 and the dust emission increased with the trend of 0.173 Tg yr−1 (R2 = 0.03, P = 0.32) in China and Mongolia over the past four decades. The spatial and temporal variations of dust emissions in China and Mongolia indicate that the annual dust flux has increased in desert areas of China and Mongolia, but decreased in most Gobi regions of China. Dust emission is significantly positively and negatively correlated with wind velocity and precipitation at the regional scale. Spatial patterns of seasonal correlations between dust flux and climate varies greatly during the period of 1980–2015.}, journal={ATMOSPHERIC ENVIRONMENT}, author={Song, Hongquan and Wang, Kai and Zhang, Yang and Hong, Chaopeng and Zhou, Shenghui}, year={2017}, month={Oct}, pages={511–522} }
 @article{zhang_zhang_wang_zhang_duan_he_2016, title={Application of WRF/Chem over East Asia: Part I. Model evaluation and intercomparison with MM5/CMAQ}, volume={124}, ISSN={["1873-2844"]}, DOI={10.1016/j.atmosenv.2015.07.022}, abstractNote={In this work, the application of the online-coupled Weather Research and Forecasting model with chemistry (WRF/Chem) version 3.3.1 is evaluated over East Asia for January, April, July, and October 2005 and compared with results from a previous application of an offline model system, i.e., the Mesoscale Model and Community Multiple Air Quality modeling system (MM5/CMAQ). The evaluation of WRF/Chem is performed using multiple observational datasets from satellites and surface networks in mainland China, Hong Kong, Taiwan, and Japan. WRF/Chem simulates well specific humidity (Q2) and downward longwave and shortwave radiation (GLW and GSW) with normalized mean biases (NMBs) within 24%, but shows moderate to large biases for temperature at 2-m (T2) (NMBs of −9.8% to 75.6%) and precipitation (NMBs of 11.4–92.7%) for some months, and wind speed at 10-m (WS10) (NMBs of 66.5–101%), for all months, indicating some limitations in the YSU planetary boundary layer scheme, the Purdue Lin cloud microphysics, and the Grell–Devenyi ensemble scheme. WRF/Chem can simulate the column abundances of gases reasonably well with NMBs within 30% for most months but moderately to significantly underpredicts the surface concentrations of major species at all sites in nearly all months with NMBs of −72% to −53.8% for CO, −99.4% to −61.7% for NOx, −84.2% to −44.5% for SO2, −63.9% to −25.2% for PM2.5, and −68.9% to 33.3% for PM10, and aerosol optical depth in all months except for October with NMBs of −38.7% to −16.2%. The model significantly overpredicts surface concentrations of O3 at most sites in nearly all months with NMBs of up to 160.3% and NO3- at the Tsinghua site in all months. Possible reasons for large underpredictions include underestimations in the anthropogenic emissions of CO, SO2, and primary aerosol, inappropriate vertical distributions of emissions of SO2 and NO2, uncertainties in upper boundary conditions (e.g., for O3 and CO), missing or inaccurate model representations (e.g., secondary organic aerosol formation, gas/particle partitioning, dust emissions, dry and wet deposition), and inaccurate meteorological fields (e.g., overpredictions in WS10 and precipitation, but underpredictions in T2), as well as the large uncertainties in satellite retrievals (e.g., for column SO2). Comparing to MM5, WRF generally gives worse performance in meteorological predictions, in particular, T2, WS10, GSW, GLW, and cloud fraction in all months, as well as Q2 and precipitation in January and October, due to limitations in the above physics schemes or parameterizations. Comparing to CMAQ, WRF/Chem performs better for surface CO, O3, and PM10 concentrations at most sites in most months, column CO and SO2 abundances, and AOD. It, however, gives poorer performance for surface NOx concentrations at most sites in most months, surface SO2 concentrations at all sites in all months, and column NO2 abundances in January and April. WRF/Chem also gives lower concentrations of most secondary PM and black carbon. Those differences in results are attributed to differences in simulated meteorology, gas-phase chemistry, aerosol thermodynamic and dynamic treatments, dust and sea salt emissions, and wet and dry deposition treatments in both models.}, journal={ATMOSPHERIC ENVIRONMENT}, author={Zhang, Yang and Zhang, Xin and Wang, Litao and Zhang, Qiang and Duan, Fengkui and He, Kebin}, year={2016}, month={Jan}, pages={285–300} }
 @article{zhang_zhang_wang_zhang_duan_he_2016, title={Application of WRF/Chem over East Asia: Part II. Model improvement and sensitivity simulations}, volume={124}, ISSN={["1873-2844"]}, DOI={10.1016/j.atmosenv.2015.07.023}, abstractNote={To address the problems and limitations identified through a comprehensive evaluation in Part I paper, several modifications are made in model inputs, treatments, and configurations and sensitivity simulations with improved model inputs and treatments are performed in this Part II paper. The use of reinitialization of meteorological variables reduces the biases and increases the spatial correlations in simulated temperature at 2-m (T2), specific humidity at 2-m (Q2), wind speed at 10-m (WS10), and precipitation (Precip). The use of a revised surface drag parameterization further reduces the biases in simulated WS10. The adjustment of only the magnitudes of anthropogenic emissions in the surface layer does not help improve overall model performance, whereas the adjustment of both the magnitudes and vertical distributions of anthropogenic emissions shows moderate to large improvement in simulated surface concentrations and column mass abundances of species in terms of domain mean performance statistics, hourly and monthly mean concentrations, and vertical profiles of concentrations at individual sites. The revised and more advanced dust emission schemes can help improve PM predictions. Using revised upper boundary conditions for O3 significantly improves the column O3 abundances. Using a simple SOA formation module further improves the predictions of organic carbon and PM2.5. The sensitivity simulation that combines all above model improvements greatly improves the overall model performance. For example, the sensitivity simulation gives the normalized mean biases (NMBs) of −6.1% to 23.8% for T2, 2.7–13.8% for Q2, 22.5–47.6% for WS10, and −9.1% to 15.6% for Precip, comparing to −9.8% to 75.6% for T2, 0.4–23.4% for Q2, 66.5–101.0% for WS10, and 11.4%–92.7% for Precip from the original simulation without those improvements. It also gives the NMBs for surface predictions of −68.2% to −3.7% for SO2, −73.8% to −20.6% for NO2, −8.8%–128.7% for O3, −61.4% to −26.5% for PM2.5, and −64.0% to 7.2% for PM10, comparing to −84.2% to −44.5% for SO2, −88.1% to −44.0% for NO2, −11.0%–160.3% for O3, −63.9% to −25.2% for PM2.5, and −68.9%–33.3% for PM10 from the original simulation. The improved WRF/Chem is applied to estimate the impact of anthropogenic aerosols on regional climate and air quality in East Asia. Anthropogenic aerosols can increase cloud condensation nuclei, aerosol optical depth, cloud droplet number concentrations, and cloud optical depth. They can decrease surface net radiation, temperature at 2-m, wind speed at 10-m, planetary boundary layer height, and precipitation through various direct and indirect effects. These changes in turn lead to changes in chemical predictions in a variety of ways.}, journal={ATMOSPHERIC ENVIRONMENT}, author={Zhang, Yang and Zhang, Xin and Wang, Kai and Zhang, Qiang and Duan, Fengkui and He, Kebin}, year={2016}, month={Jan}, pages={301–320} }
 @article{wang_zhang_wang_zheng_zhang_wei_2016, title={Application of Weather Research and Forecasting Model with Chemistry (WRF/Chem) over northern China: Sensitivity study, comparative evaluation, and policy implications}, volume={124}, ISSN={["1873-2844"]}, DOI={10.1016/j.atmosenv.2014.12.052}, abstractNote={An extremely severe and persistent haze event occurred over the middle and eastern China in January 2013, with the record-breaking high concentrations of fine particulate matter (PM2.5). In this study, an online-coupled meteorology-air quality model, the Weather Research and Forecasting Model with Chemistry (WRF/Chem), is applied to simulate this pollution episode over East Asia and northern China at 36- and 12-km grid resolutions. A number of simulations are conducted to examine the sensitivities of the model predictions to various physical schemes. The results show that all simulations give similar predictions for temperature, wind speed, wind direction, and humidity, but large variations exist in the prediction for precipitation. The concentrations of PM2.5, particulate matter with aerodynamic diameter of 10 μm or less (PM10), sulfur dioxide (SO2), and nitrogen dioxide (NO2) are overpredicted partially due to the lack of wet scavenging by the chemistry-aerosol option with the 1999 version of the Statewide Air Pollution Research Center (SAPRC-99) mechanism with the Model for Simulating Aerosol Interactions and Chemistry (MOSAIC) and the Volatility Basis Set (VBS) for secondary organic aerosol formation. The optimal set of configurations with the best performance is the simulation with the Gorddard shortwave and RRTM longwave radiation schemes, the Purdue Lin microphysics scheme, the Kain-Fritsch cumulus scheme, and a nudging coefficient of 1 × 10−5 for water vapor mixing ratio. The emission sensitivity simulations show that the PM2.5 concentrations are most sensitive to nitrogen oxide (NOx) and SO2 emissions in northern China, but to NOx and ammonia (NH3) emissions in southern China. 30% NOx emission reductions may result in an increase in PM2.5 concentrations in northern China because of the NH3-rich and volatile organic compound (VOC) limited conditions over this area. VOC emission reductions will lead to a decrease in PM2.5 concentrations in eastern China. However, 30% reductions in the emissions of SO2, NOx, NH3, and VOC, individually or collectively, are insufficient to effectively mitigate the severe pollution over northern China. More aggressive emission controls, which needs to be identified in further studies, are needed in this area to reach the objective of 25% PM2.5 concentration reduction in 2017 proposed in the Action Plan for Air Pollution Prevention and Control by the State Council in 2013.}, journal={ATMOSPHERIC ENVIRONMENT}, author={Wang, Litao and Zhang, Yang and Wang, Kai and Zheng, Bo and Zhang, Qiang and Wei, Wei}, year={2016}, month={Jan}, pages={337–350} }
 @article{liu_zhang_zhang_he_2016, title={Application of online-coupled WRF/Chem-MADRID in East Asia: Model evaluation and climatic effects of anthropogenic aerosols}, volume={124}, ISSN={["1873-2844"]}, DOI={10.1016/j.atmosenv.2015.03.052}, abstractNote={The online-coupled Weather Research and Forecasting model with Chemistry with the Model of Aerosol Dynamics, Reaction, Ionization, and Dissolution (referred to as WRF/Chem-MADRID) is applied to simulate meteorological fields, air quality, and the direct and indirect effects of anthropogenic aerosols over East Asia in four months (January, April, July, and October) in 2008. Model evaluation against available surface and satellite measurements shows that despite some model biases, WRF/Chem-MADRID is able to reproduce reasonably well the spatial and seasonal variations of most meteorological fields and chemical concentrations. Large model biases for chemical concentrations are attributed to uncertainties in emissions and their spatial and vertical allocations, simulated meteorological fields, imperfectness of model representations of aerosol formation processes, uncertainties in the observations based on air pollution index, and the use of a coarse grid resolution. The results show that anthropogenic aerosols can reduce net shortwave flux at the surface by up to 40.5–57.2 W m−2, Temperature at 2-m by up to 0.5–0.8 °C, NO2 photolytic rates by up to 0.06–0.1 min−1 and the planetary boundary layer height by up to 83.6–130.4 m. Anthropogenic aerosols contribute to the number concentrations of aerosols by up to 6.2–8.6 × 104 cm−3 and the surface cloud concentration nuclei at a supersaturation of 0.5% by up to 1.0–1.6 × 104 cm−3. They increase the column cloud droplet number concentrations by up to 3.6–11.7 × 108 cm−2 and cloud optical thickness by up to 19.8–33.2. However, anthropogenic aerosols decrease daily precipitation in most areas by up to 3.9–18.6 mm during the 4 months. These results indicate the importance of anthropogenic aerosols in modulating regional climate changes in East Asia through aerosol direct and indirect effects, as well as the need to further improve the performance of online-coupled models.}, journal={ATMOSPHERIC ENVIRONMENT}, author={Liu, Xu-Yan and Zhang, Yang and Zhang, Qiang and He, Me-Bin}, year={2016}, month={Jan}, pages={321–336} }
 @article{glotfelty_zhang_karamchandani_streets_2016, title={Changes in future air quality, deposition, and aerosol-cloud interactions under future climate and emission scenarios}, volume={139}, ISSN={["1873-2844"]}, DOI={10.1016/j.atmosenv.2016.05.008}, abstractNote={The prospect of global climate change will have wide scale impacts, such as ecological stress and human health hazards. One aspect of concern is future changes in air quality that will result from changes in both meteorological forcing and air pollutant emissions. In this study, the GU-WRF/Chem model is employed to simulate the impact of changing climate and emissions following the IPCC AR4 SRES A1B scenario. An average of 4 future years (2020, 2030, 2040, and 2050) is compared against an average of 2 current years (2001 and 2010). Under this scenario, by the Mid-21st century global air quality is projected to degrade with a global average increase of 2.5 ppb in the maximum 8-hr O3 level and of 0.3 μg m−3 in 24-hr average PM2.5. However, PM2.5 changes are more regional due to regional variations in primary aerosol emissions and emissions of gaseous precursor for secondary PM2.5. Increasing NOx emissions in this scenario combines with a wetter climate elevating levels of OH, HO2, H2O2, and the nitrate radical and increasing the atmosphere’s near surface oxidation state. This differs from findings under the RCP scenarios that experience declines in OH from reduced NOx emissions, stratospheric recovery of O3, and increases in CH4 and VOCs. Increasing NOx and O3 levels enhances the nitrogen and O3 deposition, indicating potentially enhanced crop damage and ecosystem stress under this scenario. The enhanced global aerosol level results in enhancements in aerosol optical depth, cloud droplet number concentration, and cloud optical thickness. This leads to dimming at the Earth’s surface with a global average reduction in shortwave radiation of 1.2 W m−2. This enhanced dimming leads to a more moderate warming trend and different trends in radiation than those found in NCAR’s CCSM simulation, which does not include the advanced chemistry and aerosol treatment of GU-WRF/Chem and cannot simulate the impacts of changing climate and emissions with the same level of detailed treatments. This study indicates that effective climate mitigation and emission control strategies are needed to prevent future health impact and ecosystem stress. Further, studies that are used to develop these strategies should use fully coupled models with sophisticated chemical and aerosol-interaction treatments that can provide a more realistic representation of the atmosphere.}, journal={ATMOSPHERIC ENVIRONMENT}, author={Glotfelty, Timothy and Zhang, Yang and Karamchandani, Prakash and Streets, David G.}, year={2016}, month={Aug}, pages={176–191} }
 @article{zhang_hong_yahya_li_zhang_he_2016, title={Comprehensive evaluation of multi-year real-time air quality forecasting using an online-coupled meteorology-chemistry model over southeastern United States}, volume={138}, ISSN={["1873-2844"]}, DOI={10.1016/j.atmosenv.2016.05.006}, abstractNote={An online-coupled meteorology-chemistry model, WRF/Chem-MADRID, has been deployed for real time air quality forecast (RT-AQF) in southeastern U.S. since 2009. A comprehensive evaluation of multi-year RT-AQF shows overall good performance for temperature and relative humidity at 2-m (T2, RH2), downward surface shortwave radiation (SWDOWN) and longwave radiation (LWDOWN), and cloud fraction (CF), ozone (O3) and fine particles (PM2.5) at surface, tropospheric ozone residuals (TOR) in O3 seasons (May-September), and column NO2 in winters (December-February). Moderate-to-large biases exist in wind speed at 10-m (WS10), precipitation (Precip), cloud optical depth (COT), ammonium (NH4+), sulfate (SO42−), and nitrate (NO3−) from the IMPROVE and SEARCH networks, organic carbon (OC) at IMPROVE, and elemental carbon (EC) and OC at SEARCH, aerosol optical depth (AOD) and column carbon monoxide (CO), sulfur dioxide (SO2), and formaldehyde (HCHO) in both O3 and winter seasons, column nitrogen dioxide (NO2) in O3 seasons, and TOR in winters. These biases indicate uncertainties in the boundary layer and cloud process treatments (e.g., surface roughness, microphysics cumulus parameterization), emissions (e.g., O3 and PM precursors, biogenic, mobile, and wildfire emissions), upper boundary conditions for all major gases and PM2.5 species, and chemistry and aerosol treatments (e.g., winter photochemistry, aerosol thermodynamics). The model shows overall good skills in reproducing the observed multi-year trends and inter-seasonal variability in meteorological and radiative variables such as T2, WS10, Precip, SWDOWN, and LWDOWN, and relatively well in reproducing the observed trends in surface O3 and PM2.5, but relatively poor in reproducing the observed column abundances of CO, NO2, SO2, HCHO, TOR, and AOD. The sensitivity simulations using satellite-constrained boundary conditions for O3 and CO show substantial improvement for both spatial distribution and domain-mean performance statistics. The model’s forecasting skills for air quality can be further enhanced through improving model inputs (e.g., anthropogenic emissions for urban areas and upper boundary conditions of chemical species), meteorological forecasts (e.g., WS10, Precip) and meteorologically-dependent emissions (e.g., biogenic and wildfire emissions), and model physics and chemical treatments (e.g., gas-phase chemistry in winter conditions, cloud processes and their interactions with radiation and aerosol).}, journal={ATMOSPHERIC ENVIRONMENT}, author={Zhang, Yang and Hong, Chaopeng and Yahya, Khairunnisa and Li, Qi and Zhang, Qiang and He, Kebin}, year={2016}, month={Aug}, pages={162–182} }
 @article{yahya_wang_campbell_glotfelty_he_zhang_2016, title={Decadal evaluation of regional climate, air quality, and their interactions over the continental US and their interactions using WRF/Chem version 3.6.1}, volume={9}, number={2}, journal={Geoscientific Model Development}, author={Yahya, K. and Wang, K. and Campbell, P. and Glotfelty, T. and He, J. and Zhang, Y.}, year={2016}, pages={671–695} }
 @article{duan_sun_sun_caldwell_cohen_mcnulty_aldridge_zhang_2016, title={Divergence of ecosystem services in US National Forests and Grasslands under a changing climate}, volume={6}, ISSN={["2045-2322"]}, DOI={10.1038/srep24441}, abstractNote={Abstract}, journal={SCIENTIFIC REPORTS}, author={Duan, Kai and Sun, Ge and Sun, Shanlei and Caldwell, Peter V. and Cohen, Erika C. and McNulty, Steven G. and Aldridge, Heather D. and Zhang, Yang}, year={2016}, month={Apr} }
 @article{zhang_ding_mao_nie_zhou_liu_huang_fu_2016, title={Impact of synoptic weather patterns and inter-decadal climate variability on air quality in the North China Plain during 1980–2013}, volume={124}, ISSN={1352-2310}, url={http://dx.doi.org/10.1016/J.ATMOSENV.2015.05.063}, DOI={10.1016/J.ATMOSENV.2015.05.063}, abstractNote={Potential relationships between air quality, synoptic weather patterns, and the East Asian Monsoon (EAM) over the North China Plain (NCP) were examined during the time period of 1980–2013 using a weather typing technique and ground-based air pollution index (API) data from three cities: Beijing, Tianjin and Shijiazhuang. Using the Kirchhofer method, circulation patterns during the 34-yr study period were classified into 5 categories, which were further used to understand the quantitative relationship between weather and air quality in NCP. The highest API values were associated with a stagnant weather condition when wide-spread stable conditions controlled most part of NCP, while westerly and southerly wind flowed over the northern and eastern part of this region, resulting in both the regional transport and local build-up of air pollutants. Under the continuous control of this weather pattern, API values were found to increase at a rate of 8.5 per day on average. Based on the qualitative and quantitative analysis, a significant correlation was found between the strength of EAM and inter-annual variability of frequencies of the weather patterns. The strengthening of summer/winter monsoon could increase the frequency of occurrence of cyclone/anticyclone related weather patterns. Time series of climate-induced variability in API over the 34 years were reconstructed based on the quantitative relationship between API and predominant weather patterns during 2001–2010. Significant connections between EAM and reconstructed API were found on both the inter-annual and inter-decadal scales. In winter and summer, strengthening/weakening of EAM, which was generally associated with the change of the representative circulation patterns, could improve/worsen air quality in this region.}, journal={Atmospheric Environment}, publisher={Elsevier BV}, author={Zhang, Yang and Ding, Aijun and Mao, Huiting and Nie, Wei and Zhou, Derong and Liu, Lixia and Huang, Xin and Fu, Congbin}, year={2016}, month={Jan}, pages={119–128} }
 @article{cai_zhang_wang_zhang_wang_zhang_duan_he_yu_2016, title={Incorporation of new particle formation and early growth treatments into WRF/Chem: Model improvement, evaluation, and impacts of anthropogenic aerosols over East Asia}, volume={124}, ISSN={["1873-2844"]}, DOI={10.1016/j.atmosenv.2015.05.046}, abstractNote={New particle formation (NPF) provides an important source of aerosol particles and cloud condensation nuclei, which may result in enhanced cloud droplet number concentration (CDNC) and cloud shortwave albedo. In this work, several nucleation parameterizations and one particle early growth parameterization are implemented into the online-coupled Weather Research and Forecasting model coupled with chemistry (WRF/Chem) to improve the model's capability in simulating NPF and early growth of ultrafine particles over East Asia. The default 8-bin over the size range of 39 nm–10 μm used in the Model for Simulating Aerosol Interactions and Chemistry aerosol module is expanded to the 12-bin over 1 nm–10 μm to explicitly track the formation and evolution of new particles. Although model biases remain in simulating H2SO4, condensation sink, growth rate, and formation rate, the evaluation of July 2008 simulation identifies a combination of three nucleation parameterizations (i.e., COMB) that can best represent the atmospheric nucleation processes in terms of both surface nucleation events and the resulting vertical distribution of ultrafine particle concentrations. COMB consists of a power law of Wang et al. (2011) based on activation theory for urban areas in planetary boundary layer (PBL), a power law of Boy et al. (2008) based on activation theory for non-urban areas in PBL, and the ion-mediated nucleation parameterization of YU10 for above PBL. The application and evaluation of the improved model with 12-bin and the COMB nucleation parameterization in East Asia during January, April, July, and October in 2001 show that the model has an overall reasonably good skill in reproducing most observed meteorological variables and surface and column chemical concentrations. Relatively large biases in simulated precipitation and wind speeds are due to inaccurate surface roughness and limitations in model treatments of cloud formation and aerosol-cloud-precipitation interactions. Large biases in the simulated surface concentrations of PM10, NOx, CO, SO2, and VOCs at some sites are due in part to possible underestimations of emissions and in part to inaccurate meteorological predictions. The simulations of 2001 show that anthropogenic aerosols can increase aerosol optical depth by 64.0–228.3%, CDNC by 40.2–76.4%, and cloud optical thickness by 14.3–25.3%; they can reduce surface net shortwave radiation by up to 42.5–52.8 W m−2, 2-m temperature by up to 0.34–0.83 °C, and PBL height by up to 76.8–125.9 m. Such effects are more significant than those previously reported for the U.S. and Europe.}, journal={ATMOSPHERIC ENVIRONMENT}, author={Cai, Changjie and Zhang, Xin and Wang, Kai and Zhang, Yang and Wang, Litao and Zhang, Qiang and Duan, Fengkui and He, Kebin and Yu, Shao-Cai}, year={2016}, month={Jan}, pages={262–284} }
 @misc{kumar_andrade_ynoue_fornaro_freitas_martins_martins_albuquerque_zhang_morawska_2016, title={New directions: From biofuels to wood stoves: The modern and ancient air quality challenges in the megacity of Sao Paulo}, volume={140}, ISSN={["1873-2844"]}, DOI={10.1016/j.atmosenv.2016.05.059}, abstractNote={Generally, urban green infrastructure aids in the mitigation of air pollution. However, little is known about the role of densely packed vegetation canopies, such as Pueraria lobata (Willd.) Ohwi (kudzu) in air pollution mitigation. Here, we conducted field measurements of tropospheric ozone (O3) and nitrogen oxides (NOx) concentrations on a highway embankment slope with and without kudzu canopies in Japan. We measured O3 and NOx concentrations above and within the kudzu canopies by using a passive sampler several times during the growing season in 2019. The results demonstrated that both O3 and NOx concentrations reduced within the kudzu canopy throughout the growing season, suggesting that kudzu generally acts as “vegetation barrier” for both gas pollutants along the highway roadside. Depending on meteorological and vegetative surface conditions, the reduction rate within the canopy ranged from 11% to 64% and from −2% to 33% for O3 and NOx concentrations, respectively. Considering lower canopy height but higher leaf area density of kudzu than those for urban tree plantations or forest patches along the roadside, kudzu can be useful as green infrastructure depending on situations. We also found that the higher the leaf area index of kudzu canopies, the higher the reduction rates of O3 and NOx. Depending on the maintenance cost for roadside tree planting, the minimal management without targeting the eradication of kudzu over a certain area can be an option for realizing green infrastructure at least for maintaining local air quality during the growing season.}, journal={ATMOSPHERIC ENVIRONMENT}, author={Kumar, Prashant and Andrade, Maria de Fatima and Ynoue, Rita Yuri and Fornaro, Adalgiza and Freitas, Edmilson Dias and Martins, Jorge and Martins, Leila D. and Albuquerque, Taciana and Zhang, Yang and Morawska, Lidia}, year={2016}, month={Sep}, pages={364–369} }
 @article{sun_sun_cohen_mcnulty_caldwell_duan_zhang_2016, title={Projecting water yield and ecosystem productivity across the United States by linking an ecohydrological model to WRF dynamically downscaled climate data}, volume={20}, number={2}, journal={Hydrology and Earth System Sciences}, author={Sun, S. L. and Sun, G. and Cohen, E. and McNulty, S. G. and Caldwell, P. V. and Duan, K. and Zhang, Y.}, year={2016}, pages={935–952} }
 @article{zhang_he_zhu_gantt_2016, title={Sensitivity of simulated chemical concentrations and aerosol-meteorology interactions to aerosol treatments and biogenic organic emissions in WRF/Chem}, volume={121}, ISSN={["2169-8996"]}, DOI={10.1002/2016jd024882}, abstractNote={Abstract}, number={10}, journal={JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES}, author={Zhang, Yang and He, Jian and Zhu, Shuai and Gantt, Brett}, year={2016}, month={May}, pages={6014–6048} }
 @article{zhu_sartelet_zhang_nenes_2016, title={Three-dimensional modeling of the mixing state of particles over Greater Paris}, volume={121}, ISSN={["2169-8996"]}, DOI={10.1002/2015jd024241}, abstractNote={Abstract}, number={10}, journal={JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES}, author={Zhu, Shupeng and Sartelet, Karine and Zhang, Yang and Nenes, Athanasios}, year={2016}, month={May}, pages={5930–5947} }
 @article{segura_caldwell_sun_mcnulty_zhang_2015, title={A model to predict stream water temperature across the conterminous USA}, volume={29}, ISSN={["1099-1085"]}, DOI={10.1002/hyp.10357}, abstractNote={Abstract}, number={9}, journal={HYDROLOGICAL PROCESSES}, author={Segura, Catalina and Caldwell, Peter and Sun, Ge and McNulty, Steve and Zhang, Yang}, year={2015}, month={Apr}, pages={2178–2195} }
 @article{wang_yahya_zhang_hogrefe_pouliot_knote_hodzic_san jose_perez_jiménez-guerrero_et al._2015, title={A multi-model assessment for the 2006 and 2010 simulations under the Air Quality Model Evaluation International Initiative (AQMEII) Phase 2 over North America: Part II. Evaluation of column variable predictions using satellite data}, volume={115}, ISSN={1352-2310}, url={http://dx.doi.org/10.1016/J.ATMOSENV.2014.07.044}, DOI={10.1016/J.ATMOSENV.2014.07.044}, abstractNote={Within the context of the Air Quality Model Evaluation International Initiative Phase 2 (AQMEII2) project, this part II paper performs a multi-model assessment of major column abundances of gases, radiation, aerosol, and cloud variables for 2006 and 2010 simulations with three online-coupled air quality models over the North America using available satellite data. It also provides the first comparative assessment of the capabilities of the current generation of online-coupled models in simulating column variables. Despite the use of different model configurations and meteorological initial and boundary conditions, most simulations show comparable model performance for many variables. The evaluation results show an excellent agreement between all simulations and satellite-derived radiation variables including downward surface solar radiation, longwave radiation, and top-of-atmospheric outgoing longwave radiation, as well as precipitable water vapor with domain-average normalized mean biases (NMBs) of typically less than 5% and correlation coefficient (R) typically more than 0.9. Most simulations perform well for column-integrated abundance of CO with domain-average NMBs of −9.4% to −2.2% in 2006 and −12.1% to 4.6% in 2010 and from reasonably well to fair for column NO2, HCHO, and SO2, with domain-average NMBs of −37.7% to 2.1%, −27.3% to 59.2%, and 16.1% to 114.2% in 2006, respectively, and, 12.9% to 102.1%, −25.0% to 87.6%, −65.2% to 7.4% in 2010, respectively. R values are high for CO and NO2 typically between 0.85 and 0.9 (i.e., R2 of 0.7–0.8). Tropospheric ozone residuals are overpredicted by all simulations due to overestimates of ozone profiles from boundary conditions. Model performance for cloud-related variables is mixed and generally worse compared to gases and radiation variables. Cloud fraction (CF) is well reproduced by most simulations. Other aerosol/cloud related variables such as aerosol optical depth (AOD), cloud optical thickness, cloud liquid water path, cloud condensation nuclei, and cloud droplet number concentration (CDNC) are moderately to largely underpredicted by most simulations, due to underpredictions of aerosol loadings and also indicating high uncertainties associated with the current model treatments of aerosol–cloud interactions and the need for further model development. Negative correlations are found for AOD for most simulations due to large negative biases over the western part of the domain. Inter-model discrepancies also exist for a few variables such as column abundances of HCHO and SO2 and CDNC due likely to different chemical mechanisms, biogenic emissions, and treatments of aerosol indirect effects. Most simulations can also capture the inter-annual trend observed by satellites between 2006 and 2010 for several variables such as column abundance of NO2, AOD, CF, and CDNC. Results shown in this work provide the important benchmark for future online-couple air quality model development.}, journal={Atmospheric Environment}, publisher={Elsevier BV}, author={Wang, Kai and Yahya, Khairunnisa and Zhang, Yang and Hogrefe, Christian and Pouliot, George and Knote, Christoph and Hodzic, Alma and San Jose, Roberto and Perez, Juan L. and Jiménez-Guerrero, Pedro and et al.}, year={2015}, month={Aug}, pages={587–603} }
 @article{campbell_zhang_yahya_wang_hogrefe_pouliot_knote_hodzic_san jose_perez_et al._2015, title={A multi-model assessment for the 2006 and 2010 simulations under the Air Quality Model Evaluation International Initiative (AQMEII) phase 2 over North America: Part I. Indicators of the sensitivity of O-3 and PM2.5 formation regimes}, volume={115}, ISSN={["1873-2844"]}, DOI={10.1016/j.atmosenv.2014.12.026}, abstractNote={Under the Air Quality Model Evaluation International Initiative, Phase 2 (AQMEII-2), three online-coupled air quality model simulations, with six different configurations, are analyzed for their performance, inter-model agreement, and responses to emission and meteorological changes between 2006 and 2010. In this Part I paper, we focus on evaluating O3 and PM2.5 indicator-based analyses, which are important in the development of applicable control strategies of O3 and PM2.5 pollution in different regions worldwide. The O3 indicators agree on widespread NOx-limited and localized VOC-limited conditions in the U.S. The NOy and O3/NOy indicators overpredict the extent of the VOC-limited chemistry in southeast U.S., but are more robust than the H2O2/HNO3, HCHO/NOy, and HCHO/NO2 indicators at the surface, which exhibit relatively more inter-model variability. The column HCHO/NO2 indicator is underpredicted in the O3 and non-O3 seasons, but there is regional variability. For surface PM2.5 indicators, there is good inter-model agreement for the degree of sulfate neutralization; however there are systematic underpredictions in the southeast U.S. There is relatively poor inter-model agreement for the less robust adjusted gas ratio indicator, which is largely overpredicted in the summer and both under- and overpredicted in winter in the southeast U.S. There is good inter-model agreement for the O3 indicator sensitivities, indicating a predominant shift to more NOx-limited conditions in 2010 relative to 2006. There is less agreement for PM2.5 indicator sensitivities, which are less robust, while indicating shifts to either regime due to different responses of aerosol treatments to changes in emissions and meteorology.}, journal={ATMOSPHERIC ENVIRONMENT}, author={Campbell, Patrick and Zhang, Yang and Yahya, Khairunnisa and Wang, Kai and Hogrefe, Christian and Pouliot, George and Knote, Christoph and Hodzic, Alma and San Jose, Roberto and Perez, Juan L. and et al.}, year={2015}, month={Aug}, pages={569–586} }
 @article{yahya_wang_gudoshava_glotfelty_zhang_2015, title={Application of WRF/Chem over North America under the AQMEII Phase 2: Part I. Comprehensive evaluation of 2006 simulation}, volume={115}, ISSN={["1873-2844"]}, DOI={10.1016/j.atmosenv.2014.08.063}, abstractNote={The Weather Research and Forecasting model with Chemistry (WRF/Chem) version 3.4.1 has been modified to include the Carbon Bond 2005 (CB05) gas-phase mechanism, the Modal for Aerosol Dynamics for Europe (MADE) and the Volatility Basis Set (VBS) approach for secondary organic aerosol (hereafter WRF/Chem-CB05-MADE/VBS), and aerosol-cloud-radiation feedbacks to improve predictions of secondary organic aerosols (SOA) and to study meteorology-chemistry feedbacks. In this Part I paper, a comprehensive evaluation is performed for WRF/Chem-CB05-MADE/VBS to simulate air quality over a large area in North America for the full year of 2006. Operational, diagnostic, and mechanistic evaluations have been carried out for major meteorological variables, gas and aerosol species, as well as aerosol-cloud-radiation variables against surface measurements, sounding data, and satellite data on a seasonal and annual basis. The model performs well for most meteorological variables with moderate to relatively high correlation and low mean biases (MBs), but with a cold bias of 0.8–0.9 °C in temperature, a moderate overprediction with normalized mean biases (NMBs) of 17–22% in wind speed, and large underpredictions with NMBs of −65% to −62% in cloud optical depths and cloud condensation nuclei over the ocean. Those biases are attributed to uncertainty in physical parameterizations, incomplete treatments of hydrometeors, and inaccurate aerosol predictions. The model shows moderate underpredictions in the mixing ratios of O3 with an annual NMB of −12.8% over rural and national park sites, which may be caused by biases in temperature and wind speed, underestimate in wildfire emissions, and underestimate in biogenic organic emissions (reflected by an NMB of −79.1% in simulated isoprene mixing ratio). The model performs well for PM2.5 concentrations with annual NMBs within ±10%; but with possible bias compensation for PM2.5 species concentrations. The model simulates well the domainwide organic carbon and SOA concentrations at two sites in the southeastern U.S. but it overpredicts SOA concentrations at two sites and underpredicts OC at one site in the same area. Those biases in site-specific SOA and OC predictions are attributed to underestimates in observed SOA, uncertainties in VOC emissions, inaccurate meteorology, and the inadequacies in the VBS treatment. Larger biases exist in predictions of dry and wet deposition fluxes of gas and PM species due mainly to overpredictions in their concentrations and precipitation, uncertainties in model treatments of deposition processes, and uncertainties in the CASTNET dry deposition data. Comparison of WRF and WRF/Chem simulations shows that the inclusion of chemical feedbacks to meteorology, clouds, and radiation results in improved predictions in most meteorological variables. Aerosol optical depth correlates strongly with aerosol concentration and cloud optical depth. The relationships between the aerosol and cloud variables are complex as the cloud variables are not only influenced by aerosol concentrations but by larger-scale dynamical processes.}, journal={ATMOSPHERIC ENVIRONMENT}, author={Yahya, Khairunnisa and Wang, Kai and Gudoshava, Masi Lin and Glotfelty, Timothy and Zhang, Yang}, year={2015}, month={Aug}, pages={733–755} }
 @article{chen_zhang_fan_leung_zhang_he_2015, title={Application of an online-coupled regional climate model, WRF-CAM5, over East Asia for examination of ice nucleation schemes: Part I. Comprehensive model evaluation and trend analysis for 2006 and 2011}, volume={3}, number={3}, journal={Climate}, author={Chen, Y. and Zhang, Y. and Fan, J. W. and Leung, L. Y. R. and Zhang, Q. and He, K. B.}, year={2015}, pages={627–667} }
 @article{zhang_chen_fan_leung_2015, title={Application of an online-coupled regional climate model, WRF-CAM5, over East Asia for examination of ice nucleation schemes: Part II. Sensitivity to heterogeneous ice nucleation parameterizations and dust emissions}, volume={3}, number={3}, journal={Climate}, author={Zhang, Y. and Chen, Y. and Fan, J. W. and Leung, L. Y. R.}, year={2015}, pages={753–774} }
 @article{giordano_brunner_flemming_hogrefe_im_bianconi_badia_balzarini_baró_chemel_et al._2015, title={Assessment of the MACC reanalysis and its influence as chemical boundary conditions for regional air quality modeling in AQMEII-2}, volume={115}, ISSN={1352-2310}, url={http://dx.doi.org/10.1016/J.ATMOSENV.2015.02.034}, DOI={10.1016/J.ATMOSENV.2015.02.034}, abstractNote={The Air Quality Model Evaluation International Initiative (AQMEII) has now reached its second phase which is dedicated to the evaluation of online coupled chemistry-meteorology models. Sixteen modeling groups from Europe and five from North America have run regional air quality models to simulate the year 2010 over one European and one North American domain. The MACC re-analysis has been used as chemical initial (IC) and boundary conditions (BC) by all participating regional models in AQMEII-2. The aim of the present work is to evaluate the MACC re-analysis along with the participating regional models against a set of ground-based measurements (O3, CO, NO, NO2, SO2, SO42−) and vertical profiles (O3 and CO). Results indicate different degrees of agreement between the measurements and the MACC re-analysis, with an overall better performance over the North American domain. The influence of BC on regional air quality simulations is analyzed in a qualitative way by contrasting model performance for the MACC re-analysis with that for the regional models. This approach complements more quantitative approaches documented in the literature that often have involved sensitivity simulations but typically were limited to only one or only a few regional scale models. Results suggest an important influence of the BC on ozone for which the underestimation in winter in the MACC re-analysis is mimicked by the regional models. For CO, it is found that background concentrations near the domain boundaries are rather close to observations while those over the interior of the two continents are underpredicted by both MACC and the regional models over Europe but only by MACC over North America. This indicates that emission differences between the MACC re-analysis and the regional models can have a profound impact on model performance and points to the need for harmonization of inputs in future linked global/regional modeling studies.}, journal={Atmospheric Environment}, publisher={Elsevier BV}, author={Giordano, L. and Brunner, D. and Flemming, J. and Hogrefe, C. and Im, U. and Bianconi, R. and Badia, A. and Balzarini, A. and Baró, R. and Chemel, C. and et al.}, year={2015}, month={Aug}, pages={371–388} }
 @article{giordano_brunner_flemming_hogrefe_im_bianconi_badia_balzarini_baro_chemel_et al._2015, title={Assessment of the MACC reanalysis and its influence as chemical boundary conditions for regional air quality modeling in AQMEII-2}, volume={115}, journal={Atmospheric Environment}, author={Giordano, L. and Brunner, D. and Flemming, J. and Hogrefe, C. and Im, U. and Bianconi, R. and Badia, A. and Balzarini, A. and Baro, R. and Chemel, C. and et al.}, year={2015}, pages={371–388} }
 @article{he_zhang_tilmes_emmons_lamarque_glotfelty_hodzic_vitt_2015, title={CESM/CAM5 improvement and application: comparison and evaluation of updated CB05_GE and MOZART-4 gas-phase mechanisms and associated impacts on global air quality and climate}, volume={8}, number={12}, journal={Geoscientific Model Development}, author={He, J. and Zhang, Y. and Tilmes, S. and Emmons, L. and Lamarque, J. F. and Glotfelty, T. and Hodzic, A. and Vitt, F.}, year={2015}, pages={3999–4025} }
 @article{brunner_savage_jorba_eder_giordano_badia_balzarini_baró_bianconi_chemel_et al._2015, title={Comparative analysis of meteorological performance of coupled chemistry-meteorology models in the context of AQMEII phase 2}, volume={115}, ISSN={1352-2310}, url={http://dx.doi.org/10.1016/J.ATMOSENV.2014.12.032}, DOI={10.1016/J.ATMOSENV.2014.12.032}, abstractNote={Air pollution simulations critically depend on the quality of the underlying meteorology. In phase 2 of the Air Quality Model Evaluation International Initiative (AQMEII-2), thirteen modeling groups from Europe and four groups from North America operating eight different regional coupled chemistry and meteorology models participated in a coordinated model evaluation exercise. Each group simulated the year 2010 for a domain covering either Europe or North America or both. Here were present an operational analysis of model performance with respect to key meteorological variables relevant for atmospheric chemistry processes and air quality. These parameters include temperature and wind speed at the surface and in the vertical profile, incoming solar radiation at the ground, precipitation, and planetary boundary layer heights. A similar analysis was performed during AQMEII phase 1 (Vautard et al., 2012) for offline air quality models not directly coupled to the meteorological model core as the model systems investigated here. Similar to phase 1, we found significant overpredictions of 10-m wind speeds by most models, more pronounced during night than during daytime. The seasonal evolution of temperature was well captured with monthly mean biases below 2 K over all domains. Solar incoming radiation, precipitation and PBL heights, on the other hand, showed significant spread between models and observations suggesting that major challenges still remain in the simulation of meteorological parameters relevant for air quality and for chemistry–climate interactions at the regional scale.}, journal={Atmospheric Environment}, publisher={Elsevier BV}, author={Brunner, Dominik and Savage, Nicholas and Jorba, Oriol and Eder, Brian and Giordano, Lea and Badia, Alba and Balzarini, Alessandra and Baró, Rocío and Bianconi, Roberto and Chemel, Charles and et al.}, year={2015}, month={Aug}, pages={470–498} }
 @article{brunner_savage_jorba_eder_giordano_badia_balzarini_baro_bianconi_chemel_et al._2015, title={Comparative analysis of meteorological performance of coupled chemistry-meteorology models in the context of AQMEII phase 2}, volume={115}, journal={Atmospheric Environment}, author={Brunner, D. and Savage, N. and Jorba, O. and Eder, B. and Giordano, L. and Badia, A. and Balzarini, A. and Baro, R. and Bianconi, R. and Chemel, C. and et al.}, year={2015}, pages={470–498} }
 @article{he_zhang_glotfelty_he_bennartz_rausch_sartelet_2015, title={Decadal simulation and comprehensive evaluation of CESM/CAM5.1 with advanced chemistry, aerosol microphysics, and aerosol-cloud interactions}, volume={7}, ISSN={["1942-2466"]}, DOI={10.1002/2014ms000360}, abstractNote={Abstract}, number={1}, journal={JOURNAL OF ADVANCES IN MODELING EARTH SYSTEMS}, publisher={American Geophysical Union (AGU)}, author={He, Jian and Zhang, Yang and Glotfelty, Tim and He, Ruoying and Bennartz, Ralf and Rausch, John and Sartelet, Karine}, year={2015}, month={Mar}, pages={110–141} }
 @article{sun_sun_caldwell_mcnulty_cohen_xiao_zhang_2015, title={Drought impacts on ecosystem functions of the US National Forests and Grasslands: Part I evaluation of a water and carbon balance model}, volume={353}, ISSN={["1872-7042"]}, DOI={10.1016/j.foreco.2015.03.054}, abstractNote={Understanding and quantitatively evaluating the regional impacts of climate change and variability (e.g., droughts) on forest ecosystem functions (i.e., water yield, evapotranspiration, and productivity) and services (e.g., fresh water supply and carbon sequestration) is of great importance for developing climate change adaptation strategies for National Forests and Grasslands (NFs) in the United States. However, few reliable continental-scale modeling tools are available to account for both water and carbon dynamics. The objective of this study was to test a monthly water and carbon balance model, the Water Supply Stress Index (WaSSI) model, for potential application in addressing the influences of drought on NFs ecosystem services across the conterminous United States (CONUS). The performance of the WaSSI model was comprehensively assessed with measured streamflow (Q) at 72 U.S. Geological Survey (USGS) gauging stations, and satellite-based estimates of watershed evapotranspiration (ET) and gross primary productivity (GPP) for 170 National Forest and Grassland (NFs). Across the 72 USGS watersheds, the WaSSI model generally captured the spatial variability of multi-year mean annual and monthly Q and annual ET as evaluated by Correlation Coefficient (R = 0.71–1.0), Nash–Sutcliffe Efficiency (NS = 0.31–1.00), and normalized Root Mean Squared Error (0.06–0.48). The modeled ET and GPP by WaSSI agreed well with the remote sensing-based estimates for multi-year annual and monthly means for all the NFs. However, there were systemic discrepancies in GPP between our simulations and the satellite-based estimates on a yearly and monthly scale, suggesting uncertainties in GPP estimates in all methods (i.e., remote sensing and modeling). Overall, our assessments suggested that the WaSSI model had the capability to reconstruct the long-term forest watershed water and carbon balances at a broad scale. This model evaluation study provides a foundation for model applications in understanding the impacts of climate change and variability (e.g., droughts) on NFs ecosystem service functions.}, journal={FOREST ECOLOGY AND MANAGEMENT}, author={Sun, Shanlei and Sun, Ge and Caldwell, Peter and McNulty, Steven G. and Cohen, Erika and Xiao, Jingfeng and Zhang, Yang}, year={2015}, month={Oct}, pages={260–268} }
 @article{sun_sun_caldwell_mcnulty_cohen_xiao_zhang_2015, title={Drought impacts on ecosystem functions of the US National Forests and Grasslands: Part II assessment results and management implications}, volume={353}, ISSN={["1872-7042"]}, DOI={10.1016/j.foreco.2015.04.002}, abstractNote={The 781,000 km2 (193 million acre) United States National Forests and Grasslands system (NF) provides important ecosystem services such as clean water supply, timber production, wildlife habitat, and recreation opportunities to the American public. Quantifying the historical impacts of climate change and drought on ecosystem functions at the national scale is essential to develop sound forest management and watershed restoration plans under a changing climate. This study applied the previously validated Water Supply and Stress Index model (WaSSI) to 170 NFs in the conterminous U.S. (CONUS) to examine how historical extreme droughts have affected forest water yield (Q) and gross primary productivity (GPP). For each NF, we focused on the five years with the lowest annual SPI3 (Standardized Precipitation Index on a 3-month time scale) during 1962–2012. The extent of extreme droughts as measured by the number of NFs and total area affected by droughts has increased during the last decade. Across all lands in CONUS, the most extreme drought during the past decade occurred in 2002, resulting in a mean reduction of Q by 32% and GPP by 20%. For the 170 individual NFs, on average, the top-five droughts represented a reduction in precipitation by 145 mm yr−1 (or 22%), causing reductions in evapotranspiration by 29 mm yr−1 (or 8%), Q by 110 mm yr−1 (or 37%) and GPP by 65 gC m−2 yr−1 (or 9%). The responses of the forest hydrology and productivity to the top-five droughts varied spatially due to different land-surface characteristics (e.g., climatology and vegetation) and drought severity at each NF. This study provides a comprehensive benchmark assessment of likely drought impacts on the hydrology and productivity in NFs using consistent methods and datasets across the conterminous U.S. The study results are useful to the forestry decision makers for developing appropriate strategies to restore and protect ecosystem services in anticipating potential future droughts and climate change.}, journal={FOREST ECOLOGY AND MANAGEMENT}, author={Sun, Shanlei and Sun, Ge and Caldwell, Peter and McNulty, Steve and Cohen, Erika and Xiao, Jingfeng and Zhang, Yang}, year={2015}, month={Oct}, pages={269–279} }
 @article{im_bianconi_solazzo_kioutsioukis_badia_balzarini_baró_bellasio_brunner_chemel_et al._2015, title={Evaluation of operational on-line-coupled regional air quality models over Europe and North America in the context of AQMEII phase 2. Part I: Ozone}, volume={115}, ISSN={1352-2310}, url={http://dx.doi.org/10.1016/J.ATMOSENV.2014.09.042}, DOI={10.1016/J.ATMOSENV.2014.09.042}, abstractNote={The second phase of the Air Quality Model Evaluation International Initiative (AQMEII) brought together sixteen modeling groups from Europe and North America, running eight operational online-coupled air quality models over Europe and North America on common emissions and boundary conditions. With the advent of online-coupled models providing new capability to quantify the effects of feedback processes, the main aim of this study is to compare the response of coupled air quality models to simulate levels of O3 over the two continental regions. The simulated annual, seasonal, continental and sub-regional ozone surface concentrations and vertical profiles for the year 2010 have been evaluated against a large observational database from different measurement networks operating in Europe and North America. Results show a general model underestimation of the annual surface ozone levels over both continents reaching up to 18% over Europe and 22% over North America. The observed temporal variations are successfully reproduced with correlation coefficients larger than 0.8. Results clearly show that the simulated levels highly depend on the meteorological and chemical configurations used in the models, even within the same modeling system. The seasonal and sub-regional analyses show the models' tendency to overestimate surface ozone in all regions during autumn and underestimate in winter. Boundary conditions strongly influence ozone predictions especially during winter and autumn, whereas during summer local production dominates over regional transport. Daily maximum 8-h averaged surface ozone levels below 50–60 μg m−3 are overestimated by all models over both continents while levels over 120–140 μg m−3 are underestimated, suggesting that models have a tendency to severely under-predict high O3 values that are of concern for air quality forecast and control policy applications.}, journal={Atmospheric Environment}, publisher={Elsevier BV}, author={Im, Ulas and Bianconi, Roberto and Solazzo, Efisio and Kioutsioukis, Ioannis and Badia, Alba and Balzarini, Alessandra and Baró, Rocío and Bellasio, Roberto and Brunner, Dominik and Chemel, Charles and et al.}, year={2015}, month={Aug}, pages={404–420} }
 @article{im_bianconi_solazzo_kioutsioukis_badia_balzarini_baro_bellasio_brunner_chemel_et al._2015, title={Evaluation of operational on-line-coupled regional air quality models over Europe and North America in the context of AQMEII phase 2. Part I: Ozone}, volume={115}, journal={Atmospheric Environment}, author={Im, U. and Bianconi, R. and Solazzo, E. and Kioutsioukis, I. and Badia, A. and Balzarini, A. and Baro, R. and Bellasio, R. and Brunner, D. and Chemel, C. and et al.}, year={2015}, pages={404–420} }
 @article{im_bianconi_solazzo_kioutsioukis_badia_balzarini_baró_bellasio_brunner_chemel_et al._2015, title={Evaluation of operational online-coupled regional air quality models over Europe and North America in the context of AQMEII phase 2. Part II: Particulate matter}, volume={115}, ISSN={1352-2310}, url={http://dx.doi.org/10.1016/J.ATMOSENV.2014.08.072}, DOI={10.1016/J.ATMOSENV.2014.08.072}, abstractNote={The second phase of the Air Quality Model Evaluation International Initiative (AQMEII) brought together seventeen modeling groups from Europe and North America, running eight operational online-coupled air quality models over Europe and North America using common emissions and boundary conditions. The simulated annual, seasonal, continental and sub-regional particulate matter (PM) surface concentrations for the year 2010 have been evaluated against a large observational database from different measurement networks operating in Europe and North America. The results show a systematic underestimation for all models in almost all seasons and sub-regions, with the largest underestimations for the Mediterranean region. The rural PM10 concentrations over Europe are underestimated by all models by up to 66% while the underestimations are much larger for the urban PM10 concentrations (up to 75%). On the other hand, there are overestimations in PM2.5 levels suggesting that the large underestimations in the PM10 levels can be attributed to the natural dust emissions. Over North America, there is a general underestimation in PM10 in all seasons and sub-regions by up to ∼90% due mainly to the underpredictions in soil dust. SO42− levels over EU are underestimated by majority of the models while NO3− levels are largely overestimated, particularly in east and south Europe. NH4+ levels are also underestimated largely in south Europe. SO4 levels over North America are particularly overestimated over the western US that is characterized by large anthropogenic emissions while the eastern USA is characterized by underestimated SO4 levels by the majority of the models. Daytime AOD levels at 555 nm is simulated within the 50% error range over both continents with differences attributed to differences in concentrations of the relevant species as well as in approaches in estimating the AOD. Results show that the simulated dry deposition can lead to substantial differences among the models. Overall, the results show that representation of dust and sea-salt emissions can largely impact the simulated PM concentrations and that there are still major challenges and uncertainties in simulating the PM levels.}, journal={Atmospheric Environment}, publisher={Elsevier BV}, author={Im, Ulas and Bianconi, Roberto and Solazzo, Efisio and Kioutsioukis, Ioannis and Badia, Alba and Balzarini, Alessandra and Baró, Rocío and Bellasio, Roberto and Brunner, Dominik and Chemel, Charles and et al.}, year={2015}, month={Aug}, pages={421–441} }
 @article{im_bianconi_solazzo_kioutsioukis_badia_balzarini_baro_bellasio_brunner_chemel_et al._2015, title={Evaluation of operational online-coupled regional air quality models over Europe and North America in the context of AQMEII phase 2. Part II: Particulate matter}, volume={115}, journal={Atmospheric Environment}, author={Im, U. and Bianconi, R. and Solazzo, E. and Kioutsioukis, I. and Badia, A. and Balzarini, A. and Baro, R. and Bellasio, R. and Brunner, D. and Chemel, C. and et al.}, year={2015}, pages={421–441} }
 @article{makar_gong_milbrandt_hogrefe_zhang_curci_žabkar_im_balzarini_baró_et al._2015, title={Feedbacks between air pollution and weather, Part 1: Effects on weather}, volume={115}, ISSN={1352-2310}, url={http://dx.doi.org/10.1016/J.ATMOSENV.2014.12.003}, DOI={10.1016/J.ATMOSENV.2014.12.003}, abstractNote={The meteorological predictions of fully coupled air-quality models running in “feedback” versus “no-feedback” simulations were compared against each other and observations as part of Phase 2 of the Air Quality Model Evaluation International Initiative. In the “no-feedback” mode, the aerosol direct and indirect effects were disabled, with the models reverting to either climatologies of aerosol properties, or a no-aerosol weather simulation. In the “feedback” mode, the model-generated aerosols were allowed to modify the radiative transfer and/or cloud formation parameterizations of the respective models. Annual simulations with and without feedbacks were conducted on domains over North America for the years 2006 and 2010, and over Europe for the year 2010. The incorporation of feedbacks was found to result in systematic changes to forecast predictions of meteorological variables, both in time and space, with the largest impacts occurring in the summer and near large sources of pollution. Models incorporating only the aerosol direct effect predicted feedback-induced reductions in temperature, surface downward and upward shortwave radiation, precipitation and PBL height, and increased upward shortwave radiation, in both Europe and North America. The feedback response of models incorporating both the aerosol direct and indirect effects varied across models, suggesting the details of implementation of the indirect effect have a large impact on model results, and hence should be a focus for future research. The feedback response of models incorporating both direct and indirect effects was also consistently larger in magnitude to that of models incorporating the direct effect alone, implying that the indirect effect may be the dominant process. Comparisons across modelling platforms suggested that direct and indirect effect feedbacks may often act in competition: the sign of residual changes associated with feedbacks often changed between those models incorporating the direct effect alone versus those incorporating both feedback processes. Model comparisons to observations for no-feedback and feedback implementations of the same model showed that differences in performance between models were larger than the performance changes associated with implementing feedbacks within a given model. However, feedback implementation was shown to result in improved forecasts of meteorological parameters such as the 2 m surface temperature and precipitation. These findings suggest that meteorological forecasts may be improved through the use of fully coupled feedback models, or through incorporation of improved climatologies of aerosol properties, the latter designed to include spatial, temporal and aerosol size and/or speciation variations.}, journal={Atmospheric Environment}, publisher={Elsevier BV}, author={Makar, P.A. and Gong, W. and Milbrandt, J. and Hogrefe, C. and Zhang, Y. and Curci, G. and Žabkar, R. and Im, U. and Balzarini, A. and Baró, R. and et al.}, year={2015}, month={Aug}, pages={442–469} }
 @article{makar_gong_milbrandt_hogrefe_zhang_curci_zabkar_im_balzarini_baro_et al._2015, title={Feedbacks between air pollution and weather, Part 1: Effects on weather}, volume={115}, journal={Atmospheric Environment}, author={Makar, P. A. and Gong, W. and Milbrandt, J. and Hogrefe, C. and Zhang, Y. and Curci, G. and Zabkar, R. and Im, U. and Balzarini, A. and Baro, R. and et al.}, year={2015}, pages={442–469} }
 @article{makar_gong_hogrefe_zhang_curci_žabkar_milbrandt_im_balzarini_baró_et al._2015, title={Feedbacks between air pollution and weather, part 2: Effects on chemistry}, volume={115}, ISSN={1352-2310}, url={http://dx.doi.org/10.1016/J.ATMOSENV.2014.10.021}, DOI={10.1016/J.ATMOSENV.2014.10.021}, abstractNote={Fully-coupled air-quality models running in “feedback” and “no-feedback” configurations were compared against each other and observation network data as part of Phase 2 of the Air Quality Model Evaluation International Initiative. In the “no-feedback” mode, interactions between meteorology and chemistry through the aerosol direct and indirect effects were disabled, with the models reverting to climatologies of aerosol properties, or a no-aerosol weather simulation, while in the “feedback” mode, the model-generated aerosols were allowed to modify the models' radiative transfer and/or cloud formation processes. Annual simulations with and without feedbacks were conducted for domains in North America for the years 2006 and 2010, and for Europe for the year 2010. Comparisons against observations via annual statistics show model-to-model variation in performance is greater than the within-model variation associated with feedbacks. However, during the summer and during intense emission events such as the Russian forest fires of 2010, feedbacks have a significant impact on the chemical predictions of the models. The aerosol indirect effect was usually found to dominate feedbacks compared to the direct effect. The impacts of direct and indirect effects were often shown to be in competition, for predictions of ozone, particulate matter and other species. Feedbacks were shown to result in local and regional shifts of ozone-forming chemical regime, between NOx- and VOC-limited environments. Feedbacks were shown to have a substantial influence on biogenic hydrocarbon emissions and concentrations: North American simulations incorporating both feedbacks resulted in summer average isoprene concentration decreases of up to 10%, while European direct effect simulations during the Russian forest fire period resulted in grid average isoprene changes of −5 to +12.5%. The atmospheric transport and chemistry of large emitting sources such as plumes from forest fires and large cities were shown to be strongly impacted by the presence or absence of feedback mechanisms in the model simulations. Summertime model performance for ozone and other gases was improved through the inclusion of indirect effect feedbacks, while performance for particulate matter was degraded, suggesting that current parameterizations for in- and below cloud processes, once the cloud locations become more directly influenced by aerosols, may over- or under-predict the strength of these processes. Process parameterization-level comparisons of fully coupled feedback models are therefore recommended for future work, as well as further studies using these models for the simulations of large scale urban/industrial and/or forest fire plumes.}, journal={Atmospheric Environment}, publisher={Elsevier BV}, author={Makar, P.A. and Gong, W. and Hogrefe, C. and Zhang, Y. and Curci, G. and Žabkar, R. and Milbrandt, J. and Im, U. and Balzarini, A. and Baró, R. and et al.}, year={2015}, month={Aug}, pages={499–526} }
 @article{makar_gong_hogrefe_zhang_curci_zabkar_milbrandt_im_balzarini_baro_et al._2015, title={Feedbacks between air pollution and weather, part 2: Effects on chemistry}, volume={115}, journal={Atmospheric Environment}, author={Makar, P. A. and Gong, W. and Hogrefe, C. and Zhang, Y. and Curci, G. and Zabkar, R. and Milbrandt, J. and Im, U. and Balzarini, A. and Baro, R. and et al.}, year={2015}, pages={499–526} }
 @article{zheng_zhang_zhang_he_wang_zheng_duan_ma_kimoto_2015, title={Heterogeneous chemistry: a mechanism missing in current models to explain secondary inorganic aerosol formation during the January 2013 haze episode in North China}, volume={15}, number={4}, journal={Atmospheric Chemistry and Physics}, author={Zheng, B. and Zhang, Q. and Zhang, Y. and He, K. B. and Wang, K. and Zheng, G. J. and Duan, F. K. and Ma, Y. L. and Kimoto, T.}, year={2015}, pages={2031–2049} }
 @article{wang_zhang_yahya_wu_grell_2015, title={Implementation and initial application of new chemistry-aerosol options in WRF/Chem for simulating secondary organic aerosols and aerosol indirect effects for regional air quality}, volume={115}, ISSN={["1873-2844"]}, DOI={10.1016/j.atmosenv.2014.12.007}, abstractNote={Atmospheric aerosols play important roles in affecting regional meteorology and air quality through aerosol direct and indirect effects. Two new chemistry-aerosol options have been developed in WRF/Chem v3.4.1 by incorporating the 2005 Carbon Bond (CB05) mechanism and coupling it with the existing aerosol module MADE with SORGAM and VBS modules for simulating secondary organic aerosol (SOA), aqueous-phase chemistry in both large scale and convective clouds, and aerosol feedback processes (hereafter CB05-MADE/SORGAM and CB05-MADE/VBS). As part of the Air Quality Model Evaluation International Initiative (AQMEII) Phase II model intercomparison that focuses on online-coupled meteorology and chemistry models, WRF/Chem with the two new options is applied to an area over North America for July 2006 episode. The simulations with both options can reproduce reasonably well most of the observed meteorological variables, chemical concentrations, and aerosol/cloud properties. Compared to CB05-MADE/SORGAM, CB05-MADE/VBS greatly improves the model performance for organic carbon (OC) and PM2.5, reducing NMBs from −81.2% to −13.1% and from −26.1% to −15.6%, respectively. Sensitivity simulations show that the aerosol indirect effects (including aqueous-phase chemistry) can reduce the net surface solar radiation by up to 53 W m−2 with a domainwide mean of 12 W m−2 through affecting cloud formation and radiation scattering and reflection by increasing cloud cover, which in turn reduce the surface temperature, NO2 photolytic rate, and planetary boundary layer height by up to 0.3 °C, 3.7 min−1, and 64 m, respectively. The changes of those meteorological variables further impact the air quality through the complex chemistry-aerosol-cloud-radiation interactions by reducing O3 mixing ratios by up to 5.0 ppb. The results of this work demonstrate the importance of aerosol indirect effects on the regional climate and air quality. For comparison, the impacts of aerosol direct effects on both regional meteorology and air quality are much lower with the reduction on net surface solar radiation only by up to 17 W m−2 and O3 only by up to 1.4 ppb, which indicates the importance and necessity to accurately represent the aerosol indirect effects in the online-couple regional models.}, journal={ATMOSPHERIC ENVIRONMENT}, author={Wang, Kai and Zhang, Yang and Yahya, Khairunnisa and Wu, Shiang-Yuh and Grell, Georg}, year={2015}, month={Aug}, pages={716–732} }
 @article{zhang_zhang_wang_he_leung_fan_nenes_2015, title={Incorporating an advanced aerosol activation parameterization into WRF-CAM5: Model evaluation and parameterization intercomparison}, volume={120}, ISSN={["2169-8996"]}, DOI={10.1002/2014jd023051}, abstractNote={Abstract}, number={14}, journal={JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES}, author={Zhang, Yang and Zhang, Xin and Wang, Kai and He, Jian and Leung, L. Ruby and Fan, Jiwen and Nenes, Athanasios}, year={2015}, month={Jul}, pages={6952–6979} }
 @article{knote_tuccella_curci_emmons_orlando_madronich_baro_jimenez-guerrero_luecken_hogrefe_et al._2015, title={Influence of the choice of gas-phase mechanism on predictions of key gaseous pollutants during the AQMEII phase-2 intercomparison}, volume={115}, ISSN={["1873-2844"]}, DOI={10.1016/j.atmosenv.2014.11.066}, abstractNote={The formulations of tropospheric gas-phase chemistry (“mechanisms”) used in the regional-scale chemistry-transport models participating in the Air Quality Modelling Evaluation International Initiative (AQMEII) Phase 2 are intercompared by the means of box model studies. Simulations were conducted under idealized meteorological conditions, and the results are representative of mean boundary layer concentrations. Three sets of meteorological conditions – winter, spring/autumn and summer – were used to capture the annual variability, similar to the 3-D model simulations in AQMEII Phase 2. We also employed the same emissions input data used in the 3-D model intercomparison, and sample from these datasets employing different strategies to evaluate mechanism performance under a realistic range of pollution conditions. Box model simulations using the different mechanisms are conducted with tight constraints on all relevant processes and boundary conditions (photolysis, temperature, entrainment, etc.) to ensure that differences in predicted concentrations of pollutants can be attributed to differences in the formulation of gas-phase chemistry. The results are then compared with each other (but not to measurements), leading to an understanding of mechanism-specific biases compared to the multi-model mean. Our results allow us to quantify the uncertainty in predictions of a given compound in the 3-D simulations introduced by the choice of gas-phase mechanisms, to determine mechanism-specific biases under certain pollution conditions, and to identify (or rule out) the gas-phase mechanism as the cause of an observed discrepancy in 3-D model predictions. We find that the predictions of the median diurnal cycle of O3 over a set of emission conditions representing a network of station observations is within 4 ppbv (5%) across the different mechanisms. This variability is found to be very similar on both continents. There are considerably larger differences in predicted concentrations of NOx (up to ± 25%), key radicals like OH (40%), HO2 (25%) and especially NO3 (>100%). Secondary substances like H2O2 (25%) or HNO3 (10%), as well as key volatile organic compounds like isoprene (>100%) or CH2O (20%) differ substantially as well. Calculation of an indicator of the chemical regime leads to up to 20% of simulations being classified differently by different mechanism, which would lead to different predictions of the most efficient emission reduction strategies. All these differences are despite identical meteorological boundary conditions, photolysis rates, as well as identical biogenic and inorganic anthropogenic emissions. Anthropogenic VOC emissions only vary in the way they are translated in mechanism-specific compounds, but are identical in the total emitted carbon mass and its spatial distribution. Our findings highlight that the choice of gas-phase mechanism is crucial in simulations for regulatory purposes, emission scenarios, as well as process studies that investigate other components like secondary formed aerosol components. We find that biogenic VOCs create considerable variability in mechanism predictions and suggest that these, together with nighttime chemistry should be areas of further mechanism improvement.}, journal={ATMOSPHERIC ENVIRONMENT}, author={Knote, Christoph and Tuccella, Paolo and Curci, Gabriele and Emmons, Louisa and Orlando, John J. and Madronich, Sasha and Baro, Rocio and Jimenez-Guerrero, Pedro and Luecken, Deborah and Hogrefe, Christian and et al.}, year={2015}, month={Aug}, pages={553–568} }
 @article{yahya_he_zhang_2015, title={Multiyear applications of WRF/Chem over continental US: Model evaluation, variation trend, and impacts of boundary conditions}, volume={120}, ISSN={["2169-8996"]}, DOI={10.1002/2015jd023819}, abstractNote={Abstract}, number={24}, journal={JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES}, author={Yahya, Khairunnisa and He, Jian and Zhang, Yang}, year={2015}, month={Dec}, pages={12748–12777} }
 @article{li_zhang_zhang_zheng_wang_chen_wallington_han_shen_zhang_et al._2015, title={Source contributions of urban PM2.5 in the Beijing-Tianjin-Hebei region: Changes between 2006 and 2013 and relative impacts of emissions and meteorology}, volume={123}, DOI={10.1016/j.atmosenv.2015.10.048}, abstractNote={Anthropogenic emissions in China have been controlled for years to improve ambient air quality. However, severe haze events caused by atmospheric aerosols with aerodynamic diameter less than or equal to 2.5 μm (PM2.5) have continued to occur, especially in the Beijing–Tianjin–Hebei (BTH) region. The Chinese government has set an ambitious goal to reduce urban PM2.5 concentrations by 25% in BTH by 2017 relative to the 2012 levels. Source apportionment (SA) is necessary to the development of the effective emission control strategies. In this work, the Comprehensive Air Quality Model with extensions (CAMx) with the Particulate Source Apportionment Technology (PSAT) is applied to the China domain for the years 2006 and 2013. Ambient surface concentrations of PM2.5 and its components are generally well reproduced. To quantify the contributions of each emission category or region to PM2.5 in BTH, the total emissions are divided into 7 emission categories and 11 source regions. The source contributions determined in this work are generally consistent with results from previous work. In 2013, the industrial (44%) and residential (27%) sectors are the dominant contributors to urban PM2.5 in BTH. The residential sector is the largest contributor in winter; the industry sector dominates in other seasons. A slight increasing trend (+3% for industry and +6% for residential) is found in 2013 relative to 2006, necessitating more attention to these two sectors. Local emissions make the largest contribution (40%–60%) for all receptors. Change of source contribution of PM2.5 in Beijing and northern Hebei are dominate by change of local emission. However, for Tianjin, and central and southern Hebei, change of meteorology condition are as important as change of emission, because regional inflow in these areas is more important than in Beijing and northern Hebei and can increase under unfavorable weather conditions, indicating a strong need for regional joint emission control efforts. The results in this study enhance the quantitative understanding of the source–receptor relationships and provide an important basis for policymaking to advance the control of PM2.5 pollution in China.}, journal={Atmospheric Environment}, author={Li, X. and Zhang, Q. and Zhang, Y. and Zheng, B. and Wang, K. and Chen, Y. and Wallington, T. J. and Han, W. J. and Shen, W. and Zhang, X. Y. and et al.}, year={2015}, pages={229–239} }
 @article{wang_zhang_2014, title={3-D agricultural air quality modeling: Impacts of NH3/H2S gas-phase reactions and bi-directional exchange of NH3}, volume={98}, ISSN={["1873-2844"]}, DOI={10.1016/j.atmosenv.2014.09.010}, abstractNote={Abstract Accurately simulating the transport and fate of reduced nitrogen (NHx = ammonia (NH3) + ammonium (NH4+))- and sulfur-containing compounds emitted from agricultural activities represents a major challenge in agricultural air quality modeling. In this study, the Community Multiscale Air Quality (CMAQ) modeling system is further developed and improved by implementing 22 ammonia (NH3)/hydrogen sulfide (H2S) related gas-phase reactions and adjusting a few key parameters (e.g., emission potential) for bi-directional exchange of NH3 fluxes. Several simulations are conducted over the eastern U.S. domain at a 12-km horizontal resolution for January and July 2002 to examine the impacts of those improved treatments on air quality. The 5th generation mesoscale model (MM5) and CMAQ predict an overall satisfactory and consistent performance with previous modeling studies, especially for 2-m temperature, 2-m relative humidity, ozone (O3), and fine particulate matter (PM2.5). High model biases exist for precipitation in July and also dry/wet depositions. The updated model treatments contribute to O3, NHx, and PM2.5 by up to 0.4 ppb, 1.0 μg m−3, and 1.0 μg m−3 in January, respectively, and reduce O3 by up to 0.8 ppb and contribute to NHx and PM2.5 by up to 1.2 and 1.1 μg m−3 in July, respectively. The spatial distributions of O3 in both months and sulfur dioxide (SO2) in January are mainly affected by inline dry deposition velocity calculation. The spatial distributions of SO2 and sulfate (SO42−) in July are affected by both inline dry deposition velocity and NH3/H2S reactions. The variation trends of NH3, NHx, ammonium nitrate (NH4NO3), PM2.5 and total nitrogen (TN) are predominated by bi-directional exchange of NH3 fluxes. Uncertainties of NH3 emission potentials and empirical constants used in the bi-directional exchange scheme may significantly affect the concentrations of NHx and PM2.5, indicating that a more accurate and explicit treatment for those parameters should be considered in the future work.}, journal={ATMOSPHERIC ENVIRONMENT}, author={Wang, Kai and Zhang, Yang}, year={2014}, month={Dec}, pages={554–570} }
 @article{zhang_yang_lu_zheng_dong_li_chen_zhang_chen_2014, title={Experiments of artificially triggered lightning and its application in Conghua, Guangdong, China}, volume={135-136}, ISSN={0169-8095}, url={http://dx.doi.org/10.1016/J.ATMOSRES.2013.02.010}, DOI={10.1016/J.ATMOSRES.2013.02.010}, abstractNote={The Guangdong Comprehensive Observation Experiment on Lightning Discharge (GCOELD) was conducted from 2006 to 2011 in Conghua, Guangdong, China. In GCOELD, the acoustical, optical, electrical and magnetic signals of triggered lightning and natural lightning were measured. For the triggered lightning, the peak current of the return strokes (RSs) ranged from 6.67 to 31.93 kA. The transferred charge within 1 ms after the beginning of the RS ranged from 0.44 to 4.16 C. The peak currents showed different-function correlations with average rate of rise between 10 and 90%, maximum rate of rise, charge transfer and action integral. The 2D propagation speed of the upward positive leader for the triggered lightning was of the order of 104–105 m s− 1. The speed of the downward negative leader involved in altitude-triggered lightning was approximately 105 m s− 1. The characteristics of induced voltages produced by triggered lightning on a power line and signal line of an automatic weather station were measured and analyzed. The maximum induced voltage generated by the RS on the overhead power line (1200 m in length and 2 m above the ground) exceeded 10 kV. The maximum induced voltage on a vertical 10-m signal line was 3.10 kV. The triggered-lightning technique was also used to test the detection efficiency and location precision of the lightning location system (LLS) in Guangdong. It was explored that the Guangdong LLS yielded detection efficiency and location error of 92% and 760 m, respectively, for triggered flashes. For RSs of the triggered lightning, the peak currents given by the LLS deviated from those measured at the base of the lightning channel by 16% on average.}, journal={Atmospheric Research}, publisher={Elsevier BV}, author={Zhang, Yijun and Yang, Shaojie and Lu, Weitao and Zheng, Dong and Dong, Wansheng and Li, Bin and Chen, Shaodong and Zhang, Yang and Chen, Luwen}, year={2014}, month={Jan}, pages={330–343} }
 @article{yan_winijkul_streets_lu_bond_zhang_2014, title={Global emission projections for the transportation sector using dynamic technology modeling}, volume={14}, number={11}, journal={Atmospheric Chemistry and Physics}, author={Yan, F. and Winijkul, E. and Streets, D. G. and Lu, Z. and Bond, T. C. and Zhang, Y.}, year={2014}, pages={5709–5733} }
 @article{penrod_zhang_wang_wu_leung_2014, title={Impacts of future climate and emission changes on US air quality}, volume={89}, ISSN={["1873-2844"]}, DOI={10.1016/j.atmosenv.2014.01.001}, abstractNote={Changes in climate and emissions will affect future air quality. In this work, simulations of regional air quality during current (2001–2005) and future (2026–2030) winter and summer are conducted with the newly released CMAQ version 5.0 to examine the impacts of simulated future climate and anthropogenic emission projections on air quality over the U.S. Current meteorological and chemical predictions are evaluated against observations to assess the model's capability in reproducing the seasonal differences. WRF and CMAQ capture the overall observational spatial patterns and seasonal differences. Biases in model predictions are attributed to uncertainties in emissions, boundary conditions, and limitations in model physical and chemical treatments as well as the use of a coarse grid resolution. Increased temperatures (up to 3.18 °C) and decreased ventilation (up to 157 m in planetary boundary layer height) are found in both future winter and summer, with more prominent changes in winter. Increases in future temperatures result in increased isoprene and terpene emissions in winter and summer, driving the increase in maximum 8-h average O3 (up to 5.0 ppb) over the eastern U.S. in winter while decreases in NOx emissions drive the decrease in O3 over most of the U.S. in summer. Future PM2.5 concentrations in winter and summer and many of its components decrease due to decreases in primary anthropogenic emissions and the concentrations of secondary anthropogenic pollutants as well as increased precipitation in winter. Future winter and summer dry and wet deposition fluxes are spatially variable and increase with decreasing surface resistance and precipitation, respectively. They decrease with a decrease in ambient particulate concentrations. Anthropogenic emissions play a more important role in summer than in winter for future O3 and PM2.5 levels, with a dominance of the effects of significant emission reductions over those of climate change on future PM2.5 levels.}, journal={ATMOSPHERIC ENVIRONMENT}, author={Penrod, Ashley and Zhang, Yang and Wang, Kai and Wu, Shiang-Yuh and Leung, L. Ruby}, year={2014}, month={Jun}, pages={533–547} }
 @article{zhang_wang_wu_wang_minoura_wang_2014, title={Impacts of updated emission inventories on source apportionment of fine particle and ozone over the southeastern US}, volume={88}, ISSN={["1873-2844"]}, DOI={10.1016/j.atmosenv.2014.01.035}, abstractNote={As the U.S. Environmental Protection Agency updates the National Emission Inventory (NEI), the source contributions (SC) of major source sectors to major pollutants based on source apportionment techniques should be periodically reassessed to reflect changes in SCs due to changes in emissions. This work assesses emission updates from the 1999 NEI version 2 (NEI99v2) and the 2005 NEI (NEI05) and the resulting differences in SCs using the two inventories. Large differences exist in the emissions of nitrogen oxide, formaldehyde, ammonia, terpene, and primary PM2.5 between NEI99v2 and NEI05. Differences in emissions lead to differences in model performance and source appointment. SCs of ten major source categories to fine particulate matter (PM2.5) are estimated using the Community Multiscale Air Quality modeling system with the Brute Force Method (CMAQ/BFM) andNEI05and compared with those obtained previously using CMAQ/BFM with NEI99v2. In January, compared to CMAQ/BFM (NEI99v2), CMAQ/BFM (NEI05) shows that miscellaneous areas, biomass burning, and coal combustion remain the top three contributors to PM2.5 but with different ranking and higher SCs (17.7%, 16.0%, and 14.1% for NEI05 vs. 11.8%, 13.7%, and 10.8% for NEI99v2, respectively). In July, coal combustion, miscellaneous areas, and industrial processes remain the top three with higher SCs (41.9%, 14.1%, and 8.8% for NEI05 vs.30.8%, 8.9%, and 6.9% for NEI99v2, respectively). Those changes in SCs are attributed to increased primary PM2.5 (PPM) emissions in NEI05 and increases in relative contributions of miscellaneous areas and coal combustion to the emissions of PPM, NH3, and SO2.SCs from diesel and gasoline vehicles decrease in both months, due to decreased contributions of gasoline vehicles to SO2 and NH3 emissions and those of diesel vehicles to NOx and PPM emissions. Compared with CMAQ/BFM (NEI99v2), SCs from other combustion and biomass burning are higher in Florida, due to substantial increases in formaldehyde and PPM emissions in NEI05, resulting from higher wildfire emissions and state emission updates. SCs from industrial processes increase and those from diesel and gasoline vehicles decrease in urban areas. SCs of O3 from most sources in both months increase due to a large increase in their contributions to NOx emissions, except for diesel vehicles in July, which decreases over domainwide due to a relative decrease in NOx emissions. These results provide valuable information for policy makers to formulate and adjust emission control strategies as the NEI is continuously updated.}, journal={ATMOSPHERIC ENVIRONMENT}, author={Zhang, Yang and Wang, Wei and Wu, Shiang-Yuh and Wang, Kai and Minoura, Hiroaki and Wang, Zifa}, year={2014}, month={May}, pages={133–154} }
 @article{he_zhang_2014, title={Improvement and further development in CESM/CAM5: gas-phase chemistry and inorganic aerosol treatments}, volume={14}, number={17}, journal={Atmospheric Chemistry and Physics}, author={He, J. and Zhang, Y.}, year={2014}, pages={9171–9200} }
 @article{gantt_he_zhang_zhang_nenes_2014, title={Incorporation of advanced aerosol activation treatments into CESM/CAM5: model evaluation and impacts on aerosol indirect effects}, volume={14}, number={14}, journal={Atmospheric Chemistry and Physics}, author={Gantt, B. and He, J. and Zhang, X. and Zhang, Y. and Nenes, A.}, year={2014}, pages={7485–7497} }
 @article{lim_fan_leung_ma_singh_zhao_zhang_zhang_song_2014, title={Investigation of aerosol indirect effects using a cumulus microphysics parameterization in a regional climate model}, volume={119}, ISSN={["2169-8996"]}, DOI={10.1002/2013jd020958}, abstractNote={Abstract}, number={2}, journal={JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES}, author={Lim, Kyo-Sun Sunny and Fan, Jiwen and Leung, Ruby and Ma, Po-Lun and Singh, Balwinder and Zhao, Chun and Zhang, Yang and Zhang, Guang and Song, Xiaoliang}, year={2014}, month={Jan}, pages={906–926} }
 @article{li_zhang_streets_he_cheng_emmons_huo_kang_lu_shao_et al._2014, title={Mapping Asian anthropogenic emissions of non-methane volatile organic compounds to multiple chemical mechanisms}, volume={14}, number={11}, journal={Atmospheric Chemistry and Physics}, author={Li, M. and Zhang, Q. and Streets, D. G. and He, K. B. and Cheng, Y. F. and Emmons, L. K. and Huo, H. and Kang, S. C. and Lu, Z. and Shao, M. and et al.}, year={2014}, pages={5617–5638} }
 @article{baklanov_schlunzen_suppan_baldasano_brunner_aksoyoglu_carmichael_douros_flemming_forkel_et al._2014, title={Online coupled regional meteorology chemistry models in Europe: Current status and prospects}, volume={14}, number={1}, journal={Atmospheric Chemistry and Physics}, author={Baklanov, A. and Schlunzen, K. and Suppan, P. and Baldasano, J. and Brunner, D. and Aksoyoglu, S. and Carmichael, G. and Douros, J. and Flemming, J. and Forkel, R. and et al.}, year={2014}, pages={317–398} }
 @article{yahya_zhang_vukoyich_2014, title={Real-time air quality forecasting over the southeastern United States using WRF/Chem-MADRID: Multiple-year assessment and sensitivity studies}, volume={92}, ISSN={["1873-2844"]}, DOI={10.1016/j.atmosenv.2014.04.024}, abstractNote={An air quality forecasting system is a tool for protecting public health by providing an early warning system against harmful air pollutants. In this work, the online-coupled Weather Research and Forecasting Model with Chemistry with the Model of Aerosol Dynamics, Reaction, Ionization and Dissolution (WRF/Chem-MADRID) is used to forecast ozone (O3) and fine particles (PM2.5) concentrations over the southeastern U.S. for three O3 seasons from May to September in 2009, 2010, and 2011 and three winters from December to February during 2009–2010, 2010–2011, and 2011–2012. The forecasted chemical concentrations and meteorological variables are evaluated with observations from networks data in terms of spatial distribution, temporal variation, and discrete and categorical performance statistics. The model performs well for O3 and satisfactorily for PM2.5 in terms of both discrete and categorical evaluations but larger biases exist in PM species. The model biases are due to uncertainties in meteorological predictions, emissions, boundary conditions, chemical reactions, as well as uncertainties/differences in the measurement data used for evaluation. Sensitivity simulations show that using MEGAN online biogenic emissions and satellite-derived wildfire emissions result in improved performance for PM2.5 despite a degraded performance for O3. A combination of both can reduce normalize mean bias of PM2.5 from −18.3% to −11.9%. This work identifies a need to improve the accuracy of emissions by using dynamic biogenic and fire emissions that are dependent on meteorological conditions, in addition to the needs for more accurate anthropogenic emissions for urban areas and more accurate meteorological forecasts.}, journal={ATMOSPHERIC ENVIRONMENT}, author={Yahya, Khairunnisa and Zhang, Yang and Vukoyich, Jeffrey M.}, year={2014}, month={Aug}, pages={318–338} }
 @inbook{zhang_zhang_cai_wang_wang_2014, place={Cham, Switzerland}, series={Springer Proceedings in Complexity}, title={Studying Aerosol-Cloud-Climate Interactions over East Asia Using WRF/Chem}, ISBN={9783319043784 9783319043791}, ISSN={2213-8684 2213-8692}, url={http://dx.doi.org/10.1007/978-3-319-04379-1_10}, DOI={10.1007/978-3-319-04379-1_10}, abstractNote={East Asia provides an ideal testbed to study aerosol feedbacks into climate via direct and indirect effects because of high anthropogenic emissions and unique climatology. In this work, an online coupled meteorology-chemistry model, WRF/Chem, is applied to simulate air quality and climate interactions for multiple months in 2001, 2005, and 2008 to characterize long-term seasonal variations of pollutant concentrations and quantify the contributions of anthropogenic aerosols to aerosol direct and indirect effects. The results show a reasonably good performance for most meteorological variables and chemical species concentrations. Large biases in some variables may be caused by large uncertainties in emissions. Anthropogenic aerosols in East Asia can reduce the surface net solar radiation by up to 6 % and enhance cloud condensation nuclei and cloud droplet number concentrations by a factor of up to 3 on domain-average, with much greater impacts over urban areas. These results suggest that aerosol feedbacks are potentially important over polluted areas and should be taken into account in the development of emission control and climate mitigation policies for areas where the aerosol feedback signals are strong.}, booktitle={Air Pollution Modeling and its Application XXIII}, publisher={Springer International Publishing}, author={Zhang, Yang and Zhang, Xin and Cai, Changjie and Wang, Kai and Wang, Litao}, editor={Steyn, D. and Mathur, R.Editors}, year={2014}, pages={61–66}, collection={Springer Proceedings in Complexity} }
 @article{wang_wei_yang_zhang_zhang_su_meng_zhang_2014, title={The 2013 severe haze over southern Hebei, China: model evaluation, source apportionment, and policy implications}, volume={14}, number={6}, journal={Atmospheric Chemistry and Physics}, author={Wang, L. T. and Wei, Z. and Yang, J. and Zhang, Y. and Zhang, F. F. and Su, J. and Meng, C. C. and Zhang, Q.}, year={2014}, pages={3151–3173} }
 @article{glotfelty_zhang_karamchandani_streets_2014, title={Will the role of intercontinental transport change in a changing climate?}, volume={14}, number={17}, journal={Atmospheric Chemistry and Physics}, author={Glotfelty, T. and Zhang, Y. and Karamchandani, P. and Streets, D. G.}, year={2014}, pages={9379–9402} }
 @article{zhang_zhang_lu_zheng_2013, title={Analysis and comparison of initial breakdown pulses for positive cloud-to-ground flashes observed in Beijing and Guangzhou}, volume={129-130}, ISSN={0169-8095}, url={http://dx.doi.org/10.1016/J.ATMOSRES.2013.03.006}, DOI={10.1016/J.ATMOSRES.2013.03.006}, abstractNote={In order to further understand the initiating mechanism of positive cloud-to-ground flashes, the characteristics of initial breakdown pulse trains are investigated and compared by using the data of electric field observed in Beijing and Guangzhou. According to the difference in initial polarity between initial breakdown pulse and the first return stoke, three types of initial breakdown pulse trains, including the same polarity (type I), the opposite polarity (type II) and the composite polarity (type III), have been identified. The categories of initial breakdown pulse trains in Beijing are the same as those in Guangzhou. However, in Beijing and Guangzhou, the percentages of the types are obviously different, which may be caused by different charge configuration. In Beijing, the percentages of type I, type II and type III are 55%, 39% and 6%, respectively. In Guangzhou, the percentages of type I, type II and type III are 81%, 15% and 4%, respectively. By comparsion of the pulse train parameters, it can be found that the width of individual pulse and the interval of adjacent pulses are larger in Guangzhou than those in Beijing. The difference may be caused by different discharge distance. At the same time, both in Beijing and Guangzhou, the value of pulse train duration and the ratio of the maximum peak amplitude of initial breakdown pulse train to the amplitude of first return stroke peak for type II are smaller than those for type I. However, the value of the interval between initial breakdown pulse train and first return sroke for type II is larger than that for type I. We also find that, for type II, the ratio of the maximum peak amplitude of initial breakdown pulse train to the amplitude of first return stroke peak is obviously larger in Beijing than that in Guangzhou. We believe that the intensity of initiation breakdown process as type II is larger in the region with higher latitude. It can be speculated that the intensity of initial breakdown pulse train preceding positive first return stroke is further affected by the strength of lower positive charge region. Some possible causes of the differences have been discussed.}, journal={Atmospheric Research}, publisher={Elsevier BV}, author={Zhang, Yang and Zhang, YiJun and Lu, WeiTao and Zheng, Dong}, year={2013}, month={Jul}, pages={34–41} }
 @article{zhang_sartelet_wu_seigneur_2013, title={Application of WRF/Chem-MADRID and WRF/Polyphemus in Europe - Part 1: Model description, evaluation of meteorological predictions, and aerosol-meteorology interactions}, volume={13}, number={14}, journal={Atmospheric Chemistry and Physics}, author={Zhang, Y. and Sartelet, K. and Wu, S. Y. and Seigneur, C.}, year={2013}, pages={6807–6843} }
 @article{zheng_zhang_lu_zhang_dong_chen_dan_2013, title={Characteristics of return stroke currents of classical and altitude triggered lightning in GCOELD in China}, volume={129-130}, ISSN={0169-8095}, url={http://dx.doi.org/10.1016/j.atmosres.2012.11.009}, DOI={10.1016/j.atmosres.2012.11.009}, abstractNote={The currents of 29 return strokes (RSs) involved in 10 classical triggered lightning flashes (TLFs) and an altitude TLF conducted in Guangdong, China from 2008 to 2011 are analyzed for the first time. They have relatively greater peak values (geometric mean (GM) of 16.07 kA), average rate of rise between 10 and 90% (S10–90%, GM of 29.16 kA μs− 1), charge transfer within 1 ms (Q1 ms, GM of 1.36 C) and action integral within 1 ms (AI1 ms, GM of 5.39 × 103 A2 s), compared with those reported in other studies. The current peak value exhibits pronounced exponential relation with S10–90% (determination coefficient (R2) = 0.43) and maximum rate of rise (R2 = 0.77), power relation with Q1 ms (R2 = 0.89), and logarithmic relation with AI1 ms (R2 = 0.93). Additionally, the discharges associated with the processes of initial-stage return strokes (ISRSs) involved in two altitude TLFs, with the peak currents of 10.09 kA and 9.03 kA, respectively, are investigated. Their peak, 10–90% risetime, average rate of rise between 10 and 90% and maximum rate of rise are comparable to those of the RSs. The chopped-shape pulses closely following the ISRSs and the pulses associated with the disintegration and reconnections of the wire's channel are also discussed.}, journal={Atmospheric Research}, publisher={Elsevier BV}, author={Zheng, Dong and Zhang, Yijun and Lu, Weitao and Zhang, Yang and Dong, Wansheng and Chen, Shaodong and Dan, Jianru}, year={2013}, month={Jul}, pages={67–78} }
 @article{zhou_lu_zhang_zhu_zheng_zhang_2013, title={Correlation analysis between the channel current and luminosity of initial continuous and continuing current processes in an artificially triggered lightning flash}, volume={129-130}, ISSN={0169-8095}, url={http://dx.doi.org/10.1016/j.atmosres.2012.10.020}, DOI={10.1016/j.atmosres.2012.10.020}, abstractNote={Using simultaneous high-speed camera records and channel-base current records in an artificially triggered negative lightning event, the correlation between the channel-base current and the integrated luminosity (IL) of the air-ionized part of the lightning channel is analyzed during the periods of the initial continuous current (ICC) process and eight continuing current (CC) processes. Depending on the current's changing trend (ascending or descending) and the luminosity property of the pixels used to calculate the IL from the high-speed camera records (including saturated pixels or not), the ICC and eight CC processes are divided into the saturated ascending stage (Stage-A), the saturated descending stage (Stage-B), the unsaturated ascending stage (Stage-C) and the unsaturated descending stage (Stage-D), including the descending tail stage (Stage-T, in which the channel-base current falls to zero). The analysis shows the following: (1) the IL is linearly correlated with the logarithmic value of the current in both Stage-A and Stage-B of two long CC processes, the ICC process and the CC process after the 7th return stroke, although the regression parameters (intercept and slope) in Stage-B are higher than those in Stage-A. This rule can also be found in most pulses of the long CC processes, where the IL in the descending stage is higher than that in the ascending stage at the same current value, regardless of which threshold index or height range used to calculate the IL are selected and regardless of whether the IL includes saturated pixels or not. (2) In the unsaturated stage of long CC processes, the channel current shows a significant linear correlation with the square root of the IL, and the fit of this relationship is much better than that in the saturated stage. Additionally, in each Stage-T of the eight CC processes following return strokes, the square root of the IL is significantly and linearly correlated with the current, and the regression slope is negatively correlated with the corresponding return stroke peak current. This result means that for the same channel current variation, the lower the return stroke peak current associated with the Stage-T of the CC process, the greater the luminosity variation. (3) For each of the above stages, the statistical model has a better fit when a higher threshold index, a more perpendicular channel or a greater height range is selected in the calculation of the IL.}, journal={Atmospheric Research}, publisher={Elsevier BV}, author={Zhou, Enwei and Lu, Weitao and Zhang, Yang and Zhu, Baoyou and Zheng, Dong and Zhang, Yijun}, year={2013}, month={Jul}, pages={79–89} }
 @article{zhang_wu_2013, title={Fine Scale Modeling of Agricultural Air Quality over the Southeastern United States Using Two Air Quality Models. Part II. Sensitivity Studies and Policy Implications}, volume={13}, ISSN={["2071-1409"]}, DOI={10.4209/aaqr.2012.12.0347}, abstractNote={ABSTRACTSensitivity simulations using CMAQ at various grid resolutions are evaluated. Compared with the simulations at 12- and 4-km, the 1.33-km simulation shows large improvement in most meteorological predictions in July and some chemical predictions in January and July 2002. Limited improvements at 1.33-km and 4-km are attributed to current limitations in meteorological parameterizations and lack of accurate data for land use and emissions at a fine scale. NH3 plays an important role in PM2.5 formation, but the emission control strategies focus only on SO2 and NOx in the southeastern U.S. To understand the impact of NH3, NH3 to NH4+ conversion and the chemical regimes of PM2.5 formation are examined. The conversion rates of NH3 to NH4+ from CMAQ and CAMx simulations are 10–60% in January and 10–50% in July at and near major sources. The eastern North Carolina and northeastern Georgia are NH3-rich and the remaining areas are NH3-neutral in both months. To further assess the impact of NH3 emission reductions, the sensitivity of CMAQ to emission reductions is evaluated for four emission scenarios: reducing emissions of SO2, NOx, agricultural livestock-NH3 (AL-NH3) by 50%, respectively and collectively. The largest reductions of PM2.5 are by up to 19.2% in January and 18.3% in July when all these emissions are reduced by 50%. AL-NH3 reductions result in the largest decrease in January by up to 16%, dominated by a reduction in NH4NO3, while SO2 reductions result in the largest decrease in July (up to 11%) due to decreases in NH4+ and SO42–. This indicates that reducing AL-NH3 emissions together with SO2 and NOx emissions can reduce PM2.5 concentrations more than reducing emissions of SO2 and NOx alone, particularly in winter. Future emission control strategies for PM2.5 controlling should consider the reduction of NH3 emissions, in addition to the emissions of SO2 and NOx.}, number={5}, journal={AEROSOL AND AIR QUALITY RESEARCH}, author={Zhang, Yang and Wu, Shiang-Yuh}, year={2013}, month={Oct}, pages={1475–1491} }
 @article{zhang_olsen_wang_2013, title={Fine scale modeling of agricultural air quality over the southeastern United States using two air quality models. Part I. Application and evaluation}, volume={13}, number={4}, journal={Aerosol and Air Quality Research}, author={Zhang, Y. and Olsen, K. M. and Wang, K.}, year={2013}, pages={1231–1252} }
 @article{zhang_shu_liu_zhang_yang_gan_2013, title={Heterogeneous reaction of particle-associated triphenylene with NO3 radicals}, volume={68}, ISSN={1352-2310}, url={http://dx.doi.org/10.1016/j.atmosenv.2012.11.052}, DOI={10.1016/j.atmosenv.2012.11.052}, abstractNote={Although heterogeneous reactions of polycyclic aromatic hydrocarbons (PAHs) with atmospheric oxidants may be important loss processes for PAHs, our understanding of their kinetics and products is incomplete. The study of heterogeneous reaction of suspended triphenylene particles with NO3 radicals is undertaken in a flow-tube-reactor. The time-of-flight mass spectra of particulate triphenylene and its nitration products are obtained with vacuum ultraviolet photoionization aerosol time-of-flight mass spectrometer. 1- and 2-nitrotriphenylene are identified by GC–MS analysis of the products formed from the reaction of NO3 radicals with triphenylene coated on the inner bottom surface of a conical flask. 1-Nitrotriphenylene is formed in larger yield than 2-nitrotriphenylene. This phenomenon is different from what had been observed in previous studies of the gas-phase triphenylene nitration, showing that 2-nitrotriphenylene is the major nitration product. The experimental results may reveal the discrepancies between heterogeneous and homogeneous nitrations of triphenylene.}, journal={Atmospheric Environment}, publisher={Elsevier BV}, author={Zhang, Yang and Shu, Jinian and Liu, Changgeng and Zhang, Yuanxun and Yang, Bo and Gan, Jie}, year={2013}, month={Apr}, pages={114–119} }
 @article{zhang_mao_ding_zhou_fu_2013, title={Impact of synoptic weather patterns on spatio-temporal variation in surface O3 levels in Hong Kong during 1999–2011}, volume={73}, ISSN={1352-2310}, url={http://dx.doi.org/10.1016/J.ATMOSENV.2013.02.047}, DOI={10.1016/J.ATMOSENV.2013.02.047}, abstractNote={Potential impacts of circulation patterns on surface ozone (O3) concentrations over Hong Kong were investigated for the time period of 1999–2011. Synoptic weathers during the study period were classified into seven typical patterns using a semi-objective weather typing technique. Temporal and spatial variations of O3 and total oxidant (Ox = O3 + NO2) in Hong Kong were found to be closely connected with weather/circulation patterns. The highest O3 concentrations (25 ppbv in average) among the 7 categories were found to be associated with the influence of Northwest Pacific typhoons, whereas the lowest average concentrations (13 pbbv) were linked to southerly flow introduced by summer monsoons. Ozone episodes with hourly mixing ratios exceeding 120 ppbv were found to be caused primarily by regional transport under influence of the tropical cyclone and by photochemical reactions upon prevalence of anti-cyclonic circulation. Taking into account interannual variabilities in frequency and intensity of circulation patterns, a reconstructed time series of O3 captured up to 50% of the observed interannual variability and 36% of the increasing trend. The study highlights an important linkage between weather/climate and air quality.}, journal={Atmospheric Environment}, publisher={Elsevier BV}, author={Zhang, Yang and Mao, Huiting and Ding, Aijun and Zhou, Derong and Fu, Congbin}, year={2013}, month={Jul}, pages={41–50} }
 @article{liu_zhang_2013, title={Understanding of the formation mechanisms of ozone and particulate matter at a fine scale over the southeastern US: Process analyses and responses to future-year emissions}, volume={74}, ISSN={["1873-2844"]}, DOI={10.1016/j.atmosenv.2013.03.057}, abstractNote={Ozone (O3) and fine particle (PM2.5) formation over the southeastern U.S. are of a major concern due to high emissions of precursors and special weather conditions that are conducive to their formation. In this study, the Community Multiscale Air Quality (CMAQ) modeling system is applied to simulate the formation of major air pollutants over an area in the southeastern U.S. at a 4-km horizontal grid resolution for January, April, July, and October in 2002 and 2018. Model performance evaluation shows an overall satisfactory performance for O3 in all months and for PM2.5 in January and October at rural sites and in January, April, and October at urban sites. Large underpredictions in PM2.5 concentrations occur in April and July at rural sites and in July at urban sites, because of biases in meteorological predictions and underestimation of emissions of precursors. The model performance at 4-km in terms of O3, PM2.5 and PM2.5 components show some improvements but overall are not always better than that at 12-km. O3 chemistry is VOC-limited in urban areas and NOx-limited over the west of the mountain regions and the southern Georgia throughout the year, and VOC-limited over the rest of areas in January but NOx-limited in other months. Among all photochemical indicators examined, PH2O2/PHNO3 and O3/NOy are the most robust indicators. The domain is NH3-rich or neutral in all months, indicating a high potential for NH4NO3 formation and the sensitivity of PM2.5 formation to the emissions of SO2, NOx, and NH3. Surface O3 is accumulated primarily through vertical transport in urban, rural and coastal areas and both horizontal and vertical transport in mountain regions and produced via gas-phase chemistry at non-urban sites during daytime. The loss of O3 is attributed to gas-phase chemistry via NO titration in urban areas, and dry deposition and transport processes in rural and mountain areas. PM2.5 is produced by primary emissions and PM processes and lost through vertical and horizontal transport in urban areas. The combined effects of transport, emissions, and PM processes influence PM concentrations in other areas. The 2018 simulations project a decrease in PM2.5 concentrations and an improvement in visibility over almost the entire domain, slight decreases in O3 mixing ratios in urban areas in July and most non-urban areas in April and October but large increases in the rest of areas in other months, and a decrease in total N deposition fluxes in most areas except for central and eastern North Carolina and northern Georgia. The development of integrated emission control strategies should consider region-specific seasonality and differences in the responses of O3, PM2.5, visibility, and nitrogen deposition.}, journal={ATMOSPHERIC ENVIRONMENT}, author={Liu, Xiao-Huan and Zhang, Yang}, year={2013}, month={Aug}, pages={259–276} }
 @article{chuang_zhang_kang_2012, title={Application of WRF/Chem-MADRID for real-time air quality forecasting over the Southeastern United States (vol 45, pg 6241, 2011)}, volume={60}, journal={Atmospheric Environment}, author={Chuang, M. T. and Zhang, Y. and Kang, D. W.}, year={2012}, pages={677–678} }
 @article{lu_chen_zhang_ma_gao_yin_chen_huang_zhang_2012, title={Characteristics of unconnected upward leaders initiated from tall structures observed in Guangzhou}, volume={117}, ISSN={0148-0227}, url={http://dx.doi.org/10.1029/2012JD018035}, DOI={10.1029/2012JD018035}, abstractNote={Forty‐five unconnected upward leaders (UULs) occurred in 19 downward negative flashes are analyzed. Each observed UUL is initiated by a downward stepped leader before a new strike point is struck. For each UUL, several parameters are determined when possible mainly by using high‐speed images: inception height, inception time prior to return stroke (RS), horizontal distance from the flash's strike point, two‐dimensional (2D) distance between the nearest downward leader branch tip and the UUL's inception point at its inception time, 2D length, and 2D average propagation velocity. Their values range from 40 to 503 m (number of samples: 45), <0.1 to 1.32 ms (38), 20 m to 1.3 km (38), 99 to 578 m (21), 0.48 to 399 m (45), and 5.79 to 33.8 × 104 m s−1 (22), respectively. 86% (19/22) of the velocities are smaller than 1.7 × 105 m s−1. No UUL with an inception time prior to RS greater than 0.5 ms is initiated from a structure lower than 300 m. Those UULs with inception heights lower than 300 m seldom exhibit lengths longer than 50 m and only can be initiated by flashes within approximately 600 m, while those higher than 400 m can even reach several hundred meters and be initiated by flashes over 1 km away. The maximum distances for the downward leaders to attract the UULs with inception heights from 100 to 200 m, 200 to 300 m, and over 400 m are approximately 350 m, 450 m, and 600 m, respectively.}, number={D19}, journal={Journal of Geophysical Research: Atmospheres}, publisher={American Geophysical Union (AGU)}, author={Lu, Weitao and Chen, Luwen and Zhang, Yang and Ma, Ying and Gao, Yan and Yin, Qiyuan and Chen, Shaodong and Huang, Zhihui and Zhang, Yijun}, year={2012}, month={Oct}, pages={n/a-n/a} }
 @article{bravo_fuentes_zhang_burr_bell_2012, title={Comparison of exposure estimation methods for air pollutants: Ambient monitoring data and regional air quality simulation}, volume={116}, ISSN={0013-9351}, url={http://dx.doi.org/10.1016/j.envres.2012.04.008}, DOI={10.1016/j.envres.2012.04.008}, abstractNote={Air quality modeling could potentially improve exposure estimates for use in epidemiological studies. We investigated this application of air quality modeling by estimating location-specific (point) and spatially-aggregated (county level) exposure concentrations of particulate matter with an aerodynamic diameter less than or equal to 2.5 μm (PM2.5) and ozone (O3) for the eastern U.S. in 2002 using the Community Multi-scale Air Quality (CMAQ) modeling system and a traditional approach using ambient monitors. The monitoring approach produced estimates for 370 and 454 counties for PM2.5 and O3, respectively. Modeled estimates included 1861 counties, covering 50% more population. The population uncovered by monitors differed from those near monitors (e.g., urbanicity, race, education, age, unemployment, income, modeled pollutant levels). CMAQ overestimated O3 (annual normalized mean bias=4.30%), while modeled PM2.5 had an annual normalized mean bias of −2.09%, although bias varied seasonally, from 32% in November to –27% in July. Epidemiology may benefit from air quality modeling, with improved spatial and temporal resolution and the ability to study populations far from monitors that may differ from those near monitors. However, model performance varied by measure of performance, season, and location. Thus, the appropriateness of using such modeled exposures in health studies depends on the pollutant and metric of concern, acceptable level of uncertainty, population of interest, study design, and other factors.}, journal={Environmental Research}, publisher={Elsevier BV}, author={Bravo, Mercedes A. and Fuentes, Montserrat and Zhang, Yang and Burr, Michael J. and Bell, Michelle L.}, year={2012}, month={Jul}, pages={1–10} }
 @article{karamchandani_zhang_chen_2012, title={Development and initial application of a sub-grid scale plume treatment in a state-of-the-art online Multi-scale Air Quality and Weather Prediction Model}, volume={63}, ISSN={1352-2310}, url={http://dx.doi.org/10.1016/j.atmosenv.2012.09.014}, DOI={10.1016/j.atmosenv.2012.09.014}, abstractNote={Traditional Eulerian air quality models are unable to accurately simulate sub-grid scale processes, such as the near-source transport and chemistry of point source plumes, because they assume instantaneous mixing of the emitted pollutants within the grid cell containing the release, and neglect the turbulent segregation effects that limit the near-source mixing of emitted pollutants with the background atmosphere (e.g., Kramm and Meixner, 2000). Observations by Dlugi et al. (2010) show that the segregation of chemically reactive species can slow effective second-order reaction rates by as much as 15%, due to inhomogeneous mixing of the reactants. This limitation of traditional grid models applies to both “off-line” models, in which externally derived meteorology is used to drive the chemistry model, and newer “on-line” models, such as the Weather Research and Forecasting model with Chemistry (WRF/Chem), that simulate the emissions, transport, mixing, and chemical transformation of trace gases and aerosols simultaneously with the meteorology. While a number of approaches have been used in the past to address this limitation, the approach that has been most effectively used in operational models is the plume-in-grid (PinG) approach, in which a reactive plume model is embedded within the grid model to resolve sub-grid scale plumes. This paper describes the implementation of such a PinG treatment in WRF/Chem, based on a similar extension to the U.S. EPA Community Multi-scale Air Quality (CMAQ) model. The treatment, referred to as Advanced Plume Treatment, has been tested in CMAQ over more than a decade and has been used successfully in both episodic and long-term applications for assessing point source contributions to ozone and particulate matter. This paper presents the application of the PinG version of WRF/Chem for a three-day episode in July 2001, including a model performance evaluation and comparison of model results with and without PinG treatment. The results from the model application show that overall model performance is only slightly affected when the PinG treatment is used, although there are some generally small improvements, with the PinG treatment showing a 5% lower bias in predicting ozone concentrations, and 3% lower bias in sulfate predictions. However, the predicted spatial patterns of ozone and PM2.5 concentrations from the two simulations show both large decreases of up to 40 ppb ozone and 14 μg m−3 PM2.5, and increases of up to 80 ppb ozone and 33 μg m−3 PM2.5 as a result of using the PinG treatment. These differences are attributed to both direct effects of the PinG treatment (i.e., differences in dispersion, transport and chemistry of point source emissions) and indirect effects (i.e., impacts of air quality changes on meteorology).}, journal={Atmospheric Environment}, publisher={Elsevier BV}, author={Karamchandani, Prakash and Zhang, Yang and Chen, Shu-Yun}, year={2012}, month={Dec}, pages={125–134} }
 @article{zhang_karamchandani_glotfelty_streets_grell_nenes_yu_bennartz_2012, title={Development and initial application of the global-through-urban weather research and forecasting model with chemistry (GU-WRF/Chem)}, volume={117}, ISSN={0148-0227}, url={http://dx.doi.org/10.1029/2012JD017966}, DOI={10.1029/2012JD017966}, abstractNote={A unified model framework with online‐coupled meteorology and chemistry and consistent model treatments across spatial scales is required to realistically simulate chemistry‐aerosol‐cloud‐radiation‐precipitation‐climate interactions. In this work, a global‐through‐urban WRF/Chem model (i.e., GU‐WRF/Chem) has been developed to provide such a unified model framework to simulate these important interactions across a wide range of spatial scales while reducing uncertainties from the use of offline‐coupled model systems with inconsistent model treatments. Evaluation against available observations shows that GU‐WRF/Chem is capable of reproducing observations with comparable or superior fidelity than existing mesoscale models. The net effect of atmospheric aerosols is to decrease shortwave and longwave radiation, NO2photolysis rate, near‐surface temperature, wind speed at 10‐m, planetary boundary layer height, and precipitation as well as to increase relative humidity at 2‐m, aerosol optical depths, column cloud condensation nuclei, cloud optical thickness, and cloud droplet number concentrations at all scales. As expected, such feedbacks also change the abundance and lifetimes of chemical species through changing radiation, atmospheric stability, and the rates of many meteorologically‐dependent chemical and microphysical processes. The use of higher resolutions in progressively nested domains from the global to local scale notably improves the model performance of some model predictions (especially for chemical predictions) and also captures spatial variability of aerosol feedbacks that cannot be simulated at a coarser grid resolution. Simulated aerosol, radiation, and cloud properties exhibit small‐to‐high sensitivity to various nucleation and aerosol activation parameterizations. Representing one of the few unified global‐through‐urban models, GU‐WRF/Chem can be applied to simulate air quality and its interactions with meteorology and climate and to quantify the impact of global change on urban/regional air quality across various spatial scales.}, number={D20}, journal={Journal of Geophysical Research: Atmospheres}, publisher={American Geophysical Union (AGU)}, author={Zhang, Yang and Karamchandani, Prakash and Glotfelty, Tim and Streets, David G. and Grell, Georg and Nenes, Athanasios and Yu, Fangqun and Bennartz, Ralf}, year={2012}, month={Oct} }
 @article{karamchandani_zhang_chen_balmori-bronson_2012, title={Development of an extended chemical mechanism for global-through-urban applications}, volume={3}, ISSN={["1309-1042"]}, DOI={10.5094/apr.2011.047}, abstractNote={Abstract The interactions between climate and air quality are receiving increasing attention due to their high relevancy to climate change. Coupled climate and air quality models are being developed to study these interactions. These models need to address the transport and chemistry of atmospheric species over a large range of scales and atmospheric conditions. In particular, the chemistry mechanism is a key component of such models because it needs to include the relevant reactions to simulate the chemistry of the lower troposphere, the upper troposphere, and the lower stratosphere, as well as the chemistry of polluted, rural, clean, and marine environments. This paper describes the extension of an existing chemistry mechanism for urban/regional applications, the 2005 version of the Carbon Bond Mechanism (CB05), to include the relevant atmospheric chemistry for global and global–through–urban applications. Updates to the mechanism include the most important gas–phase reactions needed for the lower stratosphere as well as reactions involving mercury species, and a number of heterogeneous reactions on aerosol particles, cloud droplets, and Polar Stratospheric Clouds (PSCs). The extended mechanism, referred to as CB05 for Global Extension (CB05_GE), is tested for a range of atmospheric conditions using a zero–dimensional box–model. A comparison of results from the extended mechanism with those from the original starting mechanism for both clean and polluted conditions in the lower troposphere shows that the extended mechanism preserves the fidelity of the original mechanism under those conditions. Simulations of marine Arctic conditions, upper tropospheric conditions, and lower stratospheric conditions with the box model illustrate the importance of halogen chemistry and heterogeneous reactions (on aerosol surfaces as well as PSCs for stratospheric conditions) for predicting ozone and elemental mercury depletion events that are often observed during these conditions. Depletions that are comparable to observed depletions are predicted by the box model for very clean conditions (extremely low or zero concentrations of aldehydes and other VOCs) because, in the absence of continuous sources of active halogens, these conditions result in less conversion of active chlorine and bromine to more stable products, such as HCl and HBr.}, number={1}, journal={ATMOSPHERIC POLLUTION RESEARCH}, author={Karamchandani, Prakash and Zhang, Yang and Chen, Shu-Yun and Balmori-Bronson, Rochelle}, year={2012}, month={Jan}, pages={1–24} }
 @article{gantt_xu_meskhidze_zhang_nenes_ghan_liu_easter_zaveri_2012, title={Global distribution and climate forcing of marine organic aerosol - Part 2: Effects on cloud properties and radiative forcing}, volume={12}, number={14}, journal={Atmospheric Chemistry and Physics}, author={Gantt, B. and Xu, J. and Meskhidze, N. and Zhang, Y. and Nenes, A. and Ghan, S. J. and Liu, X. and Easter, R. and Zaveri, R.}, year={2012}, pages={6555–6563} }
 @article{zhang_chen_sarwar_schere_2012, title={Impact of gas-phase mechanisms on Weather Research Forecasting Model with Chemistry (WRF/Chem) predictions: Mechanism implementation and comparative evaluation}, volume={117}, ISSN={0148-0227}, url={http://dx.doi.org/10.1029/2011JD015775}, DOI={10.1029/2011JD015775}, abstractNote={Gas‐phase mechanisms provide important oxidant and gaseous precursors for secondary aerosol formation. Different gas‐phase mechanisms may lead to different predictions of gases, aerosols, and aerosol direct and indirect effects. In this study, WRF/Chem‐MADRID simulations are conducted over the continental United States for July 2001, with three different gas‐phase mechanisms, a default one (i.e., CBM‐Z) and two newly implemented ones (i.e., CB05 and SAPRC‐99). Simulation results are evaluated against available surface observations, satellite data, and reanalysis data. The model with these three gas‐phase mechanisms gives similar predictions of most meteorological variables in terms of spatial distribution and statistics, but large differences exist in shortwave radiation and temperature and relative humidity at 2 m at individual sites under cloudy conditions, indicating the importance of aerosol semi‐direct and indirect effects on these variables. Large biases exist in the simulated wind speed at 10 m, cloud water path, cloud optical thickness, and precipitation, due to uncertainties in current cloud microphysics and surface layer parameterizations. Simulations with all three gas‐phase mechanisms well reproduce surface concentrations of O3, CO, NO2, and PM2.5, and column NO2. Larger biases exist in the surface concentrations of nitrate and organic matter (OM) and in the spatial distribution of column CO, tropospheric ozone residual, and aerosol optical depth, due to uncertainties in primary OM emissions, limitations in model representations of chemical transport, and radiative processes. Different gas‐phase mechanisms lead to different predictions of mass concentrations of O3 (up to 5 ppb), PM2.5 (up to 0.5 μg m−3), secondary inorganic PM2.5 species (up to 1.1 μg m−3), organic PM (up to 1.8 μg m−3), and number concentration of PM2.5 (up to 2 × 104 cm−3). Differences in aerosol mass and number concentrations further lead to sizeable differences in simulated cloud condensation nuclei (CCN) and cloud droplet number concentration (CDNC) due to the feedback mechanisms among H2SO4 vapor, PM2.5 number, CCN, and CDNC through gas‐phase chemistry, new particle formation via homogeneous nucleation, aerosol growth, and aerosol activation by cloud droplets. This study illustrates the important impact of gas‐phase mechanisms on chemical and aerosol predictions, their subsequent effects on meteorological predictions, and a need for an accurate representation of such feedbacks through various atmospheric processes in the model. The online‐coupled models that simulate feedbacks between meteorological variables and chemical species may provide more accurate representations of the real atmosphere for regulatory applications and can be applied to simulate chemistry‐climate feedbacks over a longer period of time.}, number={D1}, journal={Journal of Geophysical Research: Atmospheres}, publisher={American Geophysical Union (AGU)}, author={Zhang, Yang and Chen, Yaosheng and Sarwar, Golam and Schere, Kenneth}, year={2012}, month={Jan}, pages={n/a-n/a} }
 @article{wang_zhang_nenes_fountoukis_2012, title={Implementation of dust emission and chemistry into the community multiscale air quality modeling system and initial application to an asian dust storm episode}, volume={12}, number={21}, journal={Atmospheric Chemistry and Physics}, author={Wang, K. and Zhang, Y. and Nenes, A. and Fountoukis, C.}, year={2012}, pages={10209–10237} }
 @misc{zhang_bocquet_mallet_seigneur_baklanov_2012, title={Real-time air quality forecasting, part I: History, techniques, and current status}, volume={60}, ISSN={["1873-2844"]}, DOI={10.1016/j.atmosenv.2012.06.031}, abstractNote={Real-time air quality forecasting (RT-AQF), a new discipline of the atmospheric sciences, represents one of the most far-reaching development and practical applications of science and engineering, poses unprecedented scientific, technical, and computational challenges, and generates significant opportunities for science dissemination and community participations. This two-part review provides a comprehensive assessment of the history, current status, major research and outreach challenges, and future directions of RT-AQF, with a focus on the application and improvement of three-dimensional (3-D) deterministic RT-AQF models. In Part I, major milestones in the history of RT-AQF are reviewed. The fundamentals of RT-AQF are introduced. Various RT-AQF techniques with varying degrees of sophistication and skills are described comparatively. Among all techniques, 3-D RT-AQF models with online-coupled meteorology–chemistry and their transitions from mesoscale to unified model systems across scales represent a significant advancement and would greatly enhance understanding of the underlying complex interplay of meteorology, emission, and chemistry from global to urban scales in the real atmosphere. Current major 3-D global and regional RT-AQF models in the world are reviewed in terms of model systems, component models, application scales, model inputs, forecast products, horizontal grid resolutions, and model treatments of chemistry and aerosol processes. An important trend of such models is their coupling with an urban model or a computational fluid dynamic model for urban/local scale applications at 1 km or less and with an exposure model to provide real-time public health assessment and exposure predictions. Evaluation protocols are described along with examinations of current forecasting skills and areas with large biases of major RT-AQF models.}, journal={ATMOSPHERIC ENVIRONMENT}, author={Zhang, Yang and Bocquet, Marc and Mallet, Vivien and Seigneur, Christian and Baklanov, Alexander}, year={2012}, month={Dec}, pages={632–655} }
 @misc{zhang_bocquet_mallet_seigneur_baklanov_2012, title={Real-time air quality forecasting, part II: State of the science, current research needs, and future prospects}, volume={60}, ISSN={["1873-2844"]}, DOI={10.1016/j.atmosenv.2012.02.041}, abstractNote={The review of major 3-D global and regional real-time air quality forecasting (RT-AQF) models in Part I identifies several areas of improvement in meteorological forecasts, chemical inputs, and model treatments of atmospheric physical, dynamic, and chemical processes. Part II highlights several recent scientific advances in some of these areas that can be incorporated into RT-AQF models to address model deficiencies and improve forecast accuracies. Current major numerical, statistical, and computational techniques to improve forecasting skills are assessed. These include bias adjustment techniques to correct biases in forecast products, chemical data assimilation techniques for improving chemical initial and boundary conditions as well as emissions, and ensemble forecasting approaches to quantify the uncertainties of the forecasts. Several case applications of current 3-D RT-AQF models with the state-of-the-science model treatments, a detailed urban process module, and an advanced combined ensemble/data assimilation technique are presented to illustrate current model skills and capabilities. Major technical challenges and research priorities are provided. A new generation of comprehensive RT-AQF model systems, to emerge in the coming decades, will be based on state-of-the-science 3-D RT-AQF models, supplemented with efficient data assimilation techniques and sophisticated statistical models, and supported with modern numerical/computational technologies and a suite of real-time observational data from all platforms.}, journal={ATMOSPHERIC ENVIRONMENT}, author={Zhang, Yang and Bocquet, Marc and Mallet, Vivien and Seigneur, Christian and Baklanov, Alexander}, year={2012}, month={Dec}, pages={656–676} }
 @article{chuang_zhang_kang_2012, title={‘Erratum to “Application of WRF/Chem-MADRID for real-time air quality forecasting over the Southeastern United States” [Atmos. Environ. 45 (2011) 6241–6250]’}, volume={60}, ISSN={1352-2310}, url={http://dx.doi.org/10.1016/j.atmosenv.2012.07.019}, DOI={10.1016/j.atmosenv.2012.07.019}, abstractNote={An error was discovered in two global attributes in some emis-sion files used for real-time air quality forecasting (RT-AQF) usingWRF/Chem-MADRID: MMINLU ¼ , and ISWATER ¼ 0, whereMMINLU is a character string and enclosed in quotation marks (),indicatingthetypeoflandusecategories,andISWATERisanintegerspecifying the land use category of water. Their correct valuesshould have been MMINLU ¼ USGS (i.e., the U. S. GeologicalSurvey 24-category Land Use Categories), and ISWATER ¼ 16 (i.e.,water bodies). The incorrect ISWATER value in those files led to anincorrect assignment of a value of 1 (Land) to the landmask indexoveroceanic area (the correct landmask forocean should have been0). The impact of the incorrect MMINLU and ISWATER values overocean on the RT-AQF results and model performance presented inour paper was found to be very small. This is attributed to the factthat the WRF model physics does not predict sea-surface tempera-ture (SST) and sea ice (i.e., no oceanic processes and airesea inter-actions are treated) (NCAR, 2011). Instead, the model simulationsused SST and sea ice fields from the National Center for Environ-mental Prediction’s (NCEP)/FNL meteorological forecast.To further verify the impact and our assessment, we comparedmodel simulation results of May 2010 with incorrect and correctMMINLU and ISWATER values. The absolute differences in theforecasted mixing ratios of maximum 1-h average ozone (O}, journal={Atmospheric Environment}, publisher={Elsevier BV}, author={Chuang, Ming-Tung and Zhang, Yang and Kang, Daiwen}, year={2012}, month={Dec}, pages={677–678} }
 @article{zhang_cheng_chen_wang_2011, title={Application of MM5 in China: Model evaluation, seasonal variations, and sensitivity to horizontal grid resolutions}, volume={45}, ISSN={["1873-2844"]}, DOI={10.1016/j.atmosenv.2011.03.019}, abstractNote={The rapid growth of energy consumption in conjunction with economic development during past decades in East Asia, especially China, caused severe air pollution problems at local and regional scales. Understanding of the meteorological conditions for air pollution is essential to the understanding of the formation mechanism of air pollutants and the development of effective emission control strategies to reduce air pollution. In this paper, the Fifth Generation National Center for Atmospheric Research (NCAR)/Pennsylvania State University (PSU) Mesoscale Model (MM5) modeling system is applied to simulate meteorological fields during selected six 1-month periods in 2007/2008 over a triple-nested modeling domain covering East Asia, the eastern China, and Shandong Province at horizontal grid resolutions of 36-, 12-, and 4-km, respectively. MM5 generally reproduces well the observations in the eastern China but performs worse in the western China and northeastern China. Largest biases occur in 2-m temperatures (T2) and wind speed and wind direction at 10-m in haze months (i.e., winter) and daily mean precipitation (Precip) in non-haze months (i.e., summer), due to limitations of the model in simulating snow cover and convective precipitation. Meteorological predictions agree more closely with observations at urban sites than those at the coastal and mountain sites where the model performance deteriorates because of complex terrains, influences of urban heat island effect and land/sea breezes, and higher elevations. Model results at 12-km in Shandong Province show an overall better performance than those at 4- or 36-km while the results at 4-km show worst performance due to inaccurate land use and the model’s incapability in simulating meteorological processes at a fine scale.}, number={20}, journal={ATMOSPHERIC ENVIRONMENT}, author={Zhang, Yang and Cheng, Shu-Hui and Chen, Yao-Sheng and Wang, Wen-Xing}, year={2011}, month={Jun}, pages={3454–3465} }
 @article{chuang_zhang_kang_2011, title={Application of WRF/Chem-MADRID for real-time air quality forecasting over the Southeastern United States}, volume={45}, ISSN={["1873-2844"]}, DOI={10.1016/j.atmosenv.2011.06.071}, abstractNote={A Real-Time Air Quality Forecast (RT-AQF) system that is based on a three-dimensional air quality model provides a powerful tool to forecast air quality and advise the public with proper preventive actions. In this work, a new RT-AQF system is developed based on the online-coupled Weather Research and Forecasting model with Chemistry (WRF/Chem) with the Model of Aerosol Dynamics, Reaction, Ionization, and Dissolution (MADRID) (referred to as WRF/Chem-MADRID) and deployed in the southeastern U.S. during May–September, 2009. Max 1-h and 8-h average ozone (O3) and 24-h average fine particulate matter (PM2.5) are evaluated against surface observations from the AIRNow database in terms of spatial distribution, temporal variation, and domain-wide and region-specific discrete and categorical performance statistics. WRF/Chem-MADRID demonstrates good forecasting skill that is consistent with current RT-AQF models. The overpredictions of O3 and underprediction of PM2.5 are likely due to uncertainties in emissions such as those of biogenic volatile organic compounds (BVOCs) and ammonia, inaccuracies in simulated meteorological variables such as 2-m temperature, 10-m wind speed, and precipitation, and uncertainties in the boundary conditions. Sensitivity simulations show that the use of the online BVOC emissions can improve PM2.5 forecast in areas with high BVOC emissions and adjusting lateral boundaries can improve domain-wide O3 and PM2.5 predictions. Several limitations and uncertainties are identified to further improve the model’s forecasting skill.}, number={34}, journal={ATMOSPHERIC ENVIRONMENT}, author={Chuang, Ming-Tung and Zhang, Yang and Kang, Daiwen}, year={2011}, month={Nov}, pages={6241–6250} }
 @article{meskhidze_xu_gantt_zhang_nenes_ghan_liu_easter_zaveri_2011, title={Global distribution and climate forcing of marine organic aerosol: 1. Model improvements and evaluation}, volume={11}, number={22}, journal={Atmospheric Chemistry and Physics}, author={Meskhidze, N. and Xu, J. and Gantt, B. and Zhang, Y. and Nenes, A. and Ghan, S. J. and Liu, X. and Easter, R. and Zaveri, R.}, year={2011}, pages={11689–11705} }
 @article{xing_zhang_wang_liu_cheng_zhang_chen_streets_jang_hao_et al._2011, title={Modeling study on the air quality impacts from emission reductions and atypical meteorological conditions during the 2008 Beijing Olympics}, volume={45}, ISSN={["1873-2844"]}, DOI={10.1016/j.atmosenv.2011.01.025}, abstractNote={Understanding of the relative impacts of emission reductions and meteorological variations on air quality during the 2008 Beijing Olympics has an important policy implication. In this work, detailed process analyses and sensitivity simulations under different emission and meteorology scenarios were conducted using CMAQ and the Process Analysis tool to quantify the air quality benefits from emission reductions and meteorological variations in August 2008. The results indicate that emission-driven changes dominate surface concentration reductions of SO2, NO2, VOCs, daily maxima O3 and PM2.5 by −11% to −83%. The effect of meteorology-driven changes on species concentrations can be either ways (by −46% to 105%) at different locations. The dominant processes contributing to O3, PM2.5, SO42−, NO3−, and secondary organic aerosol (SOA) are identified. Gas-phase chemistry is a major process for O3 production, and PM processes are dominant sources for PM2.5 in the planetary boundary layer (PBL). The reduced emissions weaken the source contributions of gas-phase chemistry to O3 and those of PM processes to PM2.5, with weaker vertical mixing processes and horizontal transport in the PBL. Compared with 2007, 2008 has a higher humidity, lower temperature and more precipitation that benefit O3 reduction within the PBL, and a weaker vertical mixing that disbenefits reductions of all pollutants concentrations. Stronger process contributions of cloud processes (e.g., below- and in-cloud scavenging, and wet deposition) in 2008 help reduce concentrations of PM2.5, NO3−, and SOA, but they (e.g., aqueous-phase chemistry) enhance surface SO42− concentrations. Smaller process contributions of aerosol processes help reduce the concentrations of SOA and SO42− but enhance NO3− and PM2.5 in lower layers (1–6) due to the evaporation of NO3−. The ratios of PH2O2/PHNO3 increase under the controlled simulation, indicating that the emission control actions enforced during the 2008 Olympics weakened the sensitivity of O3 chemistry to VOC emissions in urban areas.}, number={10}, journal={ATMOSPHERIC ENVIRONMENT}, author={Xing, Jia and Zhang, Yang and Wang, Shuxiao and Liu, Xiaohuan and Cheng, Shuhui and Zhang, Qiang and Chen, Yaosheng and Streets, David G. and Jang, Carey and Hao, Jiming and et al.}, year={2011}, month={Mar}, pages={1786–1798} }
 @article{zhang_mcmurry_yu_jacobson_2010, title={A comparative study of nucleation parameterizations: 1. Examination and evaluation of the formulations}, volume={115}, ISSN={0148-0227}, url={http://dx.doi.org/10.1029/2010JD014150}, DOI={10.1029/2010JD014150}, abstractNote={Large uncertainty exists in the nucleation parameterizations that may be propagated into climate change predictions through affecting aerosol direct and indirect effects. These parameterizations are derived either empirically from laboratory/field measurements or from theoretical models for nucleation rates. A total of 12 nucleation parameterizations (7 binary, 3 ternary, and 2 power laws) that are currently used in three‐dimensional air quality models are examined comparatively under a variety of atmospheric conditions from polluted surface to very clean mesosphere environments and evaluated using observations from several laboratory experiments and a field campaign conducted in a sulfate‐rich urban environment in the southeastern United States (i.e., Atlanta, Georgia). Significant differences (by up to 18 orders of magnitude) are found among the nucleation rates calculated with different parameterizations under the same meteorological and chemical conditions. All parameterizations give nucleation rates that increase with the number concentrations of sulfuric acid but differ in terms of the magnitude of such increases. Differences exist in their dependencies on temperatures, relative humidity, and the mixing ratios of ammonia in terms of both trends and magnitudes. Among the 12 parameterizations tested, the parameterizations of Kuang et al. (2008), Sihto et al. (2006), and Harrington and Kreidenweis (1998) give the best agreement with the observed nucleation rates in most laboratory studies and in Atlanta during a summer season field campaign and either do not exceed or rarely exceed the upper limits of the nucleation rates (i.e., the dimer formation rate) and new particle formation rates (i.e., the formation rate of particles with 2 nm diameter). They are thus the most plausible nucleation parameterizations for applications in the planetary boundary layer of polluted sulfate‐rich urban areas. Limitation with the two power laws are that they were derived empirically based on observations at specific locations under certain atmospheric conditions that may be different from laboratory measurement conditions and those at other locations and that they do not consider RH and T dependence. By contrast, the ternary nucleation parameterization of Napari et al. (2002) should not be used because it grossly overpredicts the observed nucleation rates, often exceeding the upper limit dimer or new particle formation rates, and giving an enhancement factor due to the presence of ammonia and a dependence on relative humidity that are inconsistent with laboratory measurements. The binary nucleation parameterization of Wexler et al. (1994) and Kulmala et al. (1998b) also should not be used because the former gives nucleation rates exceeding the upper limits under most atmospheric conditions and the latter contains technical mistakes in its formula.}, number={D20}, journal={Journal of Geophysical Research}, publisher={American Geophysical Union (AGU)}, author={Zhang, Yang and McMurry, Peter H. and Yu, Fangqun and Jacobson, Mark Z.}, year={2010}, month={Oct} }
 @article{zhang_liu_liu_jacobson_mcmurry_yu_yu_schere_2010, title={A comparative study of nucleation parameterizations: 2. Three-dimensional model application and evaluation}, volume={115}, ISSN={0148-0227}, url={http://dx.doi.org/10.1029/2010JD014151}, DOI={10.1029/2010JD014151}, abstractNote={Following the examination and evaluation of 12 nucleation parameterizations presented in part 1, 11 of them representing binary, ternary, kinetic, and cluster‐activated nucleation theories are evaluated in the U.S. Environmental Protection Agency Community Multiscale Air Quality (CMAQ) modeling system version 4.4. The 12–28 June 1999 Southern Oxidants Study episode is selected as a testbed to evaluate simulated particulate matter (PM) number and size predictions of CMAQ with different nucleation parameterizations. The evaluation shows that simulated domain‐wide maximum PM2.5 number concentrations with different nucleation parameterizations can vary by 3 orders of magnitude. All parameterizations overpredict (by a factor of 1.4 to 1.7) the total number concentrations of accumulation‐mode PM and significantly underpredict (by factors of 1.3 to 65.7) those of Aitken‐mode PM, resulting in a net underprediction (by factors of 1.3 to 13.7) of the total number concentrations of PM2.5 under a polluted urban environment at a downtown station in Atlanta. The predicted number concentrations for Aitken‐mode PM at this site can vary by up to 3 orders of magnitude, and those for accumulation‐mode PM can vary by up to a factor of 3.2, with the best predictions by the power law of Sihto et al. (2006) (NMB of −31.7%) and the worst predictions by the ternary nucleation parameterization of Merikanto et al. (2007) (NMB of −93.1%). The ternary nucleation parameterization of Napari et al. (2002) gives relatively good agreement with observations but for a wrong reason. The power law of Kuang et al. (2008) and the binary nucleation parameterization of Harrington and Kreidenweis (1998) give better agreement than the remaining parameterizations. All the parameterizations fail to reproduce the observed temporal variations of PM number, volume, and surface area concentrations. The significant variation in the performance of these parameterizations is caused by their different theoretical bases, formulations, and dependence on temperature, relative humidity, and the ambient levels of H2SO4 and NH3. The controlling processes are different for PM number, mass, and surface areas. At urban/rural locations, some PM processes (e.g., homogeneous nucleation) and/or vertical transport may dominate the production of PM2.5 number, and emissions, or PM processes, or vertical transport or their combinations may dominate the production of PM2.5 mass and surface area. Dry deposition or some PM processes such as coagulation may dominate PM2.5 number loss, and horizontal and vertical transport, and cloud processes (e.g., cloud scavenging and wet deposition) may dominate the loss of PM2.5 mass and surface area concentrations. Sensitivity simulations show that the PM number and size distribution predictions are most sensitive to prescribed emission fractions of Aitken and accumulation‐mode PM and the assumed initial PM size distribution, in addition to different nucleation parameterizations.}, number={D20}, journal={Journal of Geophysical Research}, publisher={American Geophysical Union (AGU)}, author={Zhang, Yang and Liu, Ping and Liu, Xiao-Huan and Jacobson, Mark Z. and McMurry, Peter H. and Yu, Fangqun and Yu, Shaocai and Schere, Kenneth L.}, year={2010}, month={Oct} }
 @article{zhang_liu_liu_jacobson_mcmurry_yu_yu_schere_2010, title={A comparative study of nucleation parameterizations: 2. Three-dimensional model application and evaluation}, volume={115}, journal={Journal of Geophysical Research. Atmospheres (Online)}, author={Zhang, Y. and Liu, P. and Liu, X. H. and Jacobson, M. Z. and McMurry, P. H. and Yu, F. Q. and Yu, S. C. and Schere, K. L.}, year={2010} }
 @article{misenis_zhang_2010, title={An examination of sensitivity of WRF/Chem predictions to physical parameterizations, horizontal grid spacing, and nesting options}, volume={97}, ISSN={["1873-2895"]}, DOI={10.1016/j.atmosres.2010.04.005}, abstractNote={An accurate representation of meteorological processes is important to the accurate predictions of meteorology and air quality. In this study, the Weather Research and Forecasting model with Chemistry (WRF/Chem) is utilized to examine the sensitivity of air quality predictions to two planetary boundary layer (PBL) schemes and three land-surface models (LSMs). Model simulations with different PBL schemes and LSMs are conducted over the Houston–Galveston area for a 5-day summer episode from the 2000 Texas Air Quality Study (TexAQS-2000). Sensitivity to horizontal grid spacing (12 vs. 4 km) and nesting methods (1- or 2-way) is also studied. Model predictions are evaluated with available surface and aircraft observations. Both meteorological and chemical predictions at the surface and aloft show stronger sensitivity to LSMs than to the PBL schemes. The model predictions also show a stronger sensitivity to horizontal grid spacing using 1-way nesting than 2-way nesting and to the nesting method at 4 km than 12 km. The benefits (or disbenefits) of using more complex meteorological schemes, finer horizontal grid spacing, and more sophisticated 2-way nesting may vary and must be evaluated for specific episodes. The results from this study also indicate a need to refine model treatments at a fine grid spacing and the current 2-way nesting method used in WRF/Chem for improvement of model performance.}, number={3}, journal={ATMOSPHERIC RESEARCH}, author={Misenis, Chris and Zhang, Yang}, year={2010}, month={Aug}, pages={315–334} }
 @article{wang_jang_zhang_wang_zhang_streets_fu_lei_schreifels_he_et al._2010, title={Assessment of air quality benefits from national air pollution control policies in China. Part I: Background, emission scenarios and evaluation of meteorological predictions}, volume={44}, ISSN={["1873-2844"]}, DOI={10.1016/j.atmosenv.2010.05.051}, abstractNote={Under the 11th Five Year Plan (FYP, 2006–2010) for national environmental protection by the Chinese government, the overarching goal for sulfur dioxide (SO2) controls is to achieve a total national emissions level of SO2 in 2010 10% lower than the level in 2005. A similar nitrogen oxides (NOx) emissions control plan is currently under development and could be enforced during the 12th FYP (2011–2015). In this study, the U.S. Environmental Protection Agency (U.S.EPA)’s Community Multi-Scale Air Quality (Models-3/CMAQ) modeling system was applied to assess the air quality improvement that would result from the targeted SO2 and NOx emission controls in China. Four emission scenarios — the base year 2005, the 2010 Business-As-Usual (BAU) scenario, the 2010 SO2 control scenario, and the 2010 NOx control scenario—were constructed and simulated to assess the air quality change from the national control plan. The Fifth-Generation NCAR/Penn State Mesoscale Model (MM5) was applied to generate the meteorological fields for the CMAQ simulations. In this Part I paper, the model performance for the simulated meteorology was evaluated against observations for the base case in terms of temperature, wind speed, wind direction, and precipitation. It is shown that MM5 model gives an overall good performance for these meteorological variables. The generated meteorological fields are acceptable for using in the CMAQ modeling.}, number={28}, journal={ATMOSPHERIC ENVIRONMENT}, author={Wang, Litao and Jang, Carey and Zhang, Yang and Wang, Kai and Zhang, Qiang and Streets, David and Fu, Joshua and Lei, Yu and Schreifels, Jeremy and He, Kebin and et al.}, year={2010}, month={Sep}, pages={3442–3448} }
 @article{wang_jang_zhang_wang_zhang_streets_fu_lei_schreifels_he_et al._2010, title={Assessment of air quality benefits from national air pollution control policies in China. Part II: Evaluation of air quality predictions and air quality benefits assessment}, volume={44}, ISSN={["1873-2844"]}, DOI={10.1016/j.atmosenv.2010.05.058}, abstractNote={Following the meteorological evaluation in Part I, this Part II paper presents the statistical evaluation of air quality predictions by the U.S. Environmental Protection Agency (U.S. EPA)’s Community Multi-Scale Air Quality (Models-3/CMAQ) model for the four simulated months in the base year 2005. The surface predictions were evaluated using the Air Pollution Index (API) data published by the China Ministry of Environmental Protection (MEP) for 31 capital cities and daily fine particulate matter (PM2.5, particles with aerodiameter less than or equal to 2.5 μm) observations of an individual site in Tsinghua University (THU). To overcome the shortage in surface observations, satellite data are used to assess the column predictions including tropospheric nitrogen dioxide (NO2) column abundance and aerosol optical depth (AOD). The result shows that CMAQ gives reasonably good predictions for the air quality. The air quality improvement that would result from the targeted sulfur dioxide (SO2) and nitrogen oxides (NOx) emission controls in China were assessed for the objective year 2010. The results show that the emission controls can lead to significant air quality benefits. SO2 concentrations in highly polluted areas of East China in 2010 are estimated to be decreased by 30–60% compared to the levels in the 2010 Business-As-Usual (BAU) case. The annual PM2.5 can also decline by 3–15 μg m−3 (4–25%) due to the lower SO2 and sulfate concentrations. If similar controls are implemented for NOx emissions, NOx concentrations are estimated to decrease by 30–60% as compared with the 2010 BAU scenario. The annual mean PM2.5 concentrations will also decline by 2–14 μg m−3 (3–12%). In addition, the number of ozone (O3) non-attainment areas in the northern China is projected to be much lower, with the maximum 1-h average O3 concentrations in the summer reduced by 8–30 ppb.}, number={28}, journal={ATMOSPHERIC ENVIRONMENT}, author={Wang, Litao and Jang, Carey and Zhang, Yang and Wang, Kai and Zhang, Qiang and Streets, David and Fu, Joshua and Lei, Yu and Schreifels, Jeremy and He, Kebin and et al.}, year={2010}, month={Sep}, pages={3449–3457} }
 @article{zhang_liu_liu_pun_seigneur_jacobson_wang_2010, title={Fine scale modeling of wintertime aerosol mass, number, and size distributions in central California}, volume={115}, ISSN={0148-0227}, url={http://dx.doi.org/10.1029/2009JD012950}, DOI={10.1029/2009JD012950}, abstractNote={In light of nonattainment of PM2.5 in central California, the CMAQ‐MADRID 1 model is applied to simulate PM2.5 mass, number, and size distributions observed during the California Regional PM10/PM2.5 Air Quality Study (CRPAQS) winter episode of 25–31 December 2000. The simulations with 12 and 24 size sections at a horizontal grid resolution of 4 km reproduce well the 24 h average mass concentrations of PM2.5 (with normalized mean biases (NMBs) of −6.2% to 0.5%), but with larger biases for organic matter, nitrate, and elemental carbon (with NMBs of −67% to 40.2%) and a weaker capability of replicating temporal variation of PM2.5 and its components. The coagulation process leads to a 40%–91% reduction in simulated PM2.5 number concentrations. The 24 section simulation with coagulation shows the best agreement with the observed PM number and size distributions (with an NMB of −13.9%), indicating the importance of coagulation for predicting particle number and the merits of using a fine particle size resolution. Accurately simulating PM2.5 number and size distributions continue to be a major challenge, due to inaccuracies in model inputs (e.g., meteorological fields, precursor emissions, and the initial size distribution of PM emissions and concentrations), uncertainties in model formulations (e.g., heterogeneous chemistry and aerosol formation, growth, and removal processes), as well as inconsistencies and uncertainties in observations obtained with different methods.}, number={D15}, journal={Journal of Geophysical Research}, publisher={American Geophysical Union (AGU)}, author={Zhang, Yang and Liu, Ping and Liu, Xiao-Huan and Pun, Betty and Seigneur, Christian and Jacobson, Mark Z. and Wang, Wen-Xing}, year={2010}, month={Aug} }
 @article{zhang_liu_liu_pun_seigneur_jacobson_wang_2010, title={Fine scale modeling of wintertime aerosol mass, number, and size distributions in central California}, volume={115}, journal={Journal of Geophysical Research. Atmospheres (Online)}, author={Zhang, Y. and Liu, P. and Liu, X. H. and Pun, B. and Seigneur, C. and Jacobson, M. Z. and Wang, W. X.}, year={2010} }
 @article{liu_zhang_olsen_wang_do_bridgers_2010, title={Responses of future air quality to emission controls over North Carolina, Part I: Model evaluation for current-year simulations}, volume={44}, ISSN={["1873-2844"]}, DOI={10.1016/j.atmosenv.2010.04.002}, abstractNote={The prediction of future air quality and its responses to emission control strategies at national and state levels requires a reliable model that can replicate atmospheric observations. In this work, the Mesoscale Model (MM5) and the Community Multiscale Air Quality Modeling (CMAQ) system are applied at a 4-km horizontal grid resolution for four one-month periods, i.e., January, June, July, and August in 2002 to evaluate model performance and compare with that at 12-km. The evaluation shows skills of MM5/CMAQ that are overall consistent with current model performance. The large cold bias in temperature at 1.5 m is likely due to too cold soil initial temperatures and inappropriate snow treatments. The large overprediction in precipitation in July is due likely to too frequent afternoon convective rainfall and/or an overestimation in the rainfall intensity. The normalized mean biases and errors are −1.6% to 9.1% and 15.3–18.5% in January and −18.7% to −5.7% and 13.9–20.6% in July for max 1-h and 8-h O3 mixing ratios, respectively, and those for 24-h average PM2.5 concentrations are 8.3–25.9% and 27.6–38.5% in January and −57.8% to −45.4% and 46.1–59.3% in July. The large underprediction in PM2.5 in summer is attributed mainly to overpredicted precipitation, inaccurate emissions, incomplete treatments for secondary organic aerosols, and model difficulties in resolving complex meteorology and geography. While O3 prediction shows relatively less sensitivity to horizontal grid resolutions, PM2.5 and its secondary components, visibility indices, and dry and wet deposition show a moderate to high sensitivity. These results have important implications for the regulatory applications of MM5/CMAQ for future air quality attainment.}, number={20}, journal={ATMOSPHERIC ENVIRONMENT}, author={Liu, Xiao-Huan and Zhang, Yang and Olsen, Kristen M. and Wang, Wen-Xing and Do, Bebhinn A. and Bridgers, George M.}, year={2010}, month={Jun}, pages={2443–2456} }
 @article{zhang_liu_olsen_wang_do_bridgers_2010, title={Responses of future air quality to emission controls over North Carolina, Part II: Analyses of future-year predictions and their policy implications}, volume={44}, ISSN={["1873-2844"]}, DOI={10.1016/j.atmosenv.2010.03.022}, abstractNote={The MM5/CMAQ system evaluated in Part I paper is applied to study the impact of emission control on future air quality over North Carolina (NC). Simulations are conducted at a 4-km horizontal grid resolution for four one-month periods, i.e., January, June, July, and August 2009 and 2018. Simulated PM2.5 in 2009 and 2018 show distribution patterns similar to those in 2002. PM2.5 concentrations over the whole domain in January and July reduced by 5.8% and 23.3% in 2009 and 12.0% and 35.6% in 2018, respectively, indicating that the planned emission control strategy has noticeable effects on PM2.5 reduction in this region, particularly in summer. More than 10% and 20% of 1-h and 8-h O3 mixing ratios are reduced in July 2009 and 2018, respectively, demonstrating the effectiveness of emission control for O3 reduction in summer. However, O3 mixing ratios in January 2009 and 2018 increase by more than 5% because O3 chemistry is VOC-limited in winter and the effect of NOx reduction dominates over that of VOC reduction under such a condition. The projected emission control simulated at 4-km will reduce the number of sites in non-attainment for max 8-h O3 from 49 to 23 in 2009 and to 1 in 2018 and for 24-h average PM2.5 from 1 to 0 in 2009 and 2018 based on the latest 2008 O3 and 2006 PM2.5 standards. The variability in model predictions at different grid resolutions contributes to 1–3.8 ppb and 1–7.9 μg m−3 differences in the projected future-year design values for max 8-h O3 and 24-h average PM2.5, respectively.}, number={23}, journal={ATMOSPHERIC ENVIRONMENT}, author={Zhang, Yang and Liu, Xiao-Huan and Olsen, Kristen M. and Wang, Wen-Xing and Do, Bebhinn A. and Bridgers, George M.}, year={2010}, month={Jul}, pages={2767–2779} }
 @article{zhang_wen_jang_2010, title={Simulating chemistry–aerosol–cloud–radiation–climate feedbacks over the continental U.S. using the online-coupled Weather Research Forecasting Model with chemistry (WRF/Chem)}, volume={44}, ISSN={1352-2310}, url={http://dx.doi.org/10.1016/j.atmosenv.2010.05.056}, DOI={10.1016/j.atmosenv.2010.05.056}, abstractNote={The chemistry–aerosol–cloud–radiation–climate feedbacks are simulated using WRF/Chem over the continental U.S. in January and July 2001. Aerosols can reduce incoming solar radiation by up to −9% in January and −16% in July and 2-m temperatures by up to 0.16 °C in January and 0.37 °C in July over most of the continental U.S. The NO2 photolysis rates decrease in July by up to −8% over the central and eastern U.S. where aerosol concentrations are high but increase by up to 7% over the western U.S. in July and up to 13% over the entire domain in January. Planetary boundary layer (PBL) height reduces by up to −23% in January and −24% in July. Temperatures and wind speeds in July in big cities such as Atlanta and New York City reduce at/near surface but increase at higher altitudes. The changes in PBL height, temperatures, and wind speed indicate a more stable atmospheric stability of the PBL and further exacerbate air pollution over areas where air pollution is already severe. Aerosols can increase cloud optical depths in big cities in July, and can lead to 500–5000 cm−3 cloud condensation nuclei (CCN) at a supersaturation of 1% over most land areas and 10–500 cm−3 CCN over ocean in both months with higher values over most areas in July than in January, particularly in the eastern U.S. The total column cloud droplet number concentrations are up to 4.9 × 106 cm−2 in January and up to 11.8 × 106 cm−2 in July, with higher values over regions with high CCN concentrations and sufficient cloud coverage. Aerosols can reduce daily precipitation by up to 1.1 mm day−1 in January and 19.4 mm day−1 in July thus the wet removal rates over most of the land areas due to the formation of small CCNs, but they can increase precipitation over regions with the formation of large/giant CCN. These results indicate potential importance of the aerosol feedbacks and an urgent need for their accurate representations in current atmospheric models to reduce uncertainties associated with climate change predictions.}, number={29}, journal={Atmospheric Environment}, publisher={Elsevier BV}, author={Zhang, Yang and Wen, X.-Y. and Jang, C.J.}, year={2010}, month={Sep}, pages={3568–3582} }
 @article{gantt_meskhidze_zhang_xu_2010, title={The effect of marine isoprene emissions on secondary organic aerosol and ozone formation in the coastal United States}, volume={44}, DOI={10.1016/j.atmosenv.2009.08.027}, abstractNote={The impact of marine isoprene emissions on summertime surface concentrations of isoprene, secondary organic aerosols (SOA), and ozone (O3) in the coastal areas of the continental United States is studied using the U.S. Environmental Protection Agency regional-scale Community Multiscale Air Quality (CMAQ) modeling system. Marine isoprene emission rates are based on the following five parameters: laboratory measurements of isoprene production from phytoplankton under a range of light conditions, remotely-sensed chlorophyll-a concentration ([Chl–a]), incoming solar radiation, surface wind speed, and sea-water optical properties. Model simulations show that marine isoprene emissions are sensitive to meteorology and ocean ecosystem productivity, with the highest rates simulated over the Gulf of Mexico. Simulated offshore surface layer marine isoprene concentration is less than 10 ppt and significantly dwarfed by terrestrial emissions over the continental United States. With the isoprene reactions included in this study, the average contribution of marine isoprene to SOA and O3 concentrations is predicted to be small, up to 0.004 μg m−3 for SOA and 0.2 ppb for O3 in coastal urban areas. The light-sensitivity of isoprene production from phytoplankton results in a midday maximum for marine isoprene emissions and a corresponding daytime increase in isoprene and O3 concentrations in coastal locations. The potential impact of the daily variability in [Chl-a] on O3 and SOA concentrations is simulated in a sensitivity study with [Chl-a] increased and decreased by a factor of five. Our results indicate that marine emissions of isoprene cause minor changes to coastal SOA and O3 concentrations. Comparison of model simulations with few available measurements shows that the model underestimates marine boundary layer isoprene concentration. This underestimation is likely due to the limitations in current treatment of marine isoprene emission and a coarse spatial resolution used in the model simulations.}, number={1}, journal={Atmospheric Environment}, author={Gantt, B. and Meskhidze, N. and Zhang, Y. and Xu, J.}, year={2010}, pages={115–121} }
 @article{liu_zhang_cheng_xing_zhang_streets_jang_wang_hao_2010, title={Understanding of regional air pollution over China using CMAQ, part I performance evaluation and seasonal variation}, volume={44}, ISSN={["1873-2844"]}, DOI={10.1016/j.atmosenv.2010.03.035}, abstractNote={The U.S. EPA Models-3 Community Multiscale Air Quality (CMAQ) modeling system with the process analysis tool is applied to China to study the seasonal variations and formation mechanisms of major air pollutants. Simulations show distinct seasonal variations, with higher surface concentrations of sulfur dioxide (SO2), nitrogen dioxide (NO2), and particulate matter with aerodynamic diameter less than or equal to 10 μm (PM10), column mass of carbon monoxide (CO) and NO2, and aerosol optical depth (AOD) in winter and fall than other seasons, and higher 1-h O3 and troposphere ozone residual (TOR) in spring and summer than other seasons. Higher concentrations of most species occur over the eastern China, where the air pollutant emissions are the highest in China. Compared with surface observations, the simulated SO2, NO2, and PM10 concentrations are underpredicted throughout the year with NMBs of up to −51.8%, −32.0%, and −54.2%, respectively. Such large discrepancies can be attributed to the uncertainties in emissions, simulated meteorology, and deviation of observations based on air pollution index. Max. 1-h O3 concentrations in Jan. and Jul. at 36-km are overpredicted with NMBs of 12.0% and 19.3% and agree well in Apr. and Oct. Simulated column variables can capture the high concentrations over the eastern China and low values in the central and western China. Underpredictions occur over the northeastern China for column CO in Apr., TOR in Jul., and AODs in both Apr. and Jul.; and overpredictions occur over the eastern China for column CO in Oct., NO2 in Jan. and Oct., and AODs in Jan. and Oct. The simulations at 12-km show a finer structure in simulated concentrations than that at 36-km over higher polluted areas, but do not always give better performance than 36-km. Surface concentrations are more sensitive to grid resolution than column variables except for column NO2, with higher sensitivity over mountain and coastal areas than other regions.}, number={20}, journal={ATMOSPHERIC ENVIRONMENT}, author={Liu, Xiao-Huan and Zhang, Yang and Cheng, Shu-Hui and Xing, Jia and Zhang, Qiang and Streets, David G. and Jang, Carey and Wang, Wen-Xing and Hao, Ji-Ming}, year={2010}, month={Jun}, pages={2415–2426} }
 @article{liu_zhang_xing_zhang_wang_streets_jang_wang_hao_2010, title={Understanding of regional air pollution over China using CMAQ, part II. Process analysis and sensitivity of ozone and particulate matter to precursor emissions}, volume={44}, ISSN={["1873-2844"]}, DOI={10.1016/j.atmosenv.2010.03.036}, abstractNote={Following model evaluation in part I, this part II paper focuses on the process analysis and chemical regime analysis for the formation of ozone (O3) and particulate matter with aerodynamic diameter less than or equal to 10 μm (PM10) in China. The process analysis results show that horizontal transport is the main contributor to the accumulation of O3 in Jan., Apr., and Oct., and gas-phase chemistry and vertical transport contribute to the production and accumulation of O3 in Jul. Removal pathways of O3 include vertical and horizontal transport, gas-phase chemistry, and cloud processes, depending on locations and seasons. PM10 is mainly produced by primary emissions and aerosol processes and removed by horizontal transport. Cloud processes could either decrease or increase PM10 concentrations, depending on locations and seasons. Among all indicators examined, the ratio of PHNO3/PH2O2 provides the most robust indicator for O3 chemistry, indicating a VOC-limited O3 chemistry over most of the eastern China in Jan., NOx-limited in Jul., and either VOC- or NOx-limited in Apr. and Oct. O3 chemistry is NOx-limited in most central and western China and VOC-limited in major cities throughout the year. The adjusted gas ratio, AdjGR, indicates that PM formation in the eastern China is most sensitive to the emissions of SO2 and may be more sensitive to emission reductions in NOx than in NH3. These results are fairly consistent with the responses of O3 and PM2.5 to the reductions of their precursor emissions predicted from sensitivity simulations. A 50% reduction of NOx or AVOC emissions leads to a reduction of O3 over the eastern China. Unlike the reduction of emissions of SO2, NOx, and NH3 that leads to a decrease in PM10, a 50% reduction of AVOC emissions increases PM10 levels. Such results indicate the complexity of O3 and PM chemistry and a need for an integrated, region-specific emission control strategy with seasonal variations to effectively control both O3 and PM2.5 pollution in China.}, number={30}, journal={ATMOSPHERIC ENVIRONMENT}, author={Liu, Xiao-Huan and Zhang, Yang and Xing, Jia and Zhang, Qiang and Wang, Kai and Streets, David G. and Jang, Carey and Wang, Wen-Xing and Hao, Ji-Ming}, year={2010}, month={Sep}, pages={3719–3727} }
 @article{zhang_pan_wang_fast_grell_2010, title={WRF/Chem-MADRID: Incorporation of an aerosol module into WRF/Chem and its initial application to the TexAQS2000 episode}, volume={115}, ISSN={0148-0227}, url={http://dx.doi.org/10.1029/2009JD013443}, DOI={10.1029/2009JD013443}, abstractNote={The Model of Aerosol Dynamics, Reaction, Ionization and Dissolution (MADRID) with three improved gas/particle mass transfer approaches (i.e., bulk equilibrium (EQUI), hybrid (HYBR), and kinetic (KINE)) has been incorporated into the Weather Research and Forecast/Chemistry Model (WRF/Chem) (referred to as WRF/Chem‐MADRID) and evaluated with a 5‐day episode from the 2000 Texas Air Quality Study (TexAQS2000). WRF/Chem‐MADRID demonstrates an overall good skill in simulating surface/aloft meteorological parameters and chemical concentrations of O3 and PM2.5, tropospheric O3 residuals, and aerosol optical depths. The discrepancies can be attributed to inaccuracies in meteorological predictions (e.g., overprediction in mid‐day boundary layer height), sensitivity to meteorological schemes used (e.g., boundary layer and land‐surface schemes), inaccurate total emissions or their hourly variations (e.g., HCHO, olefins, other inorganic aerosols) or uncounted wildfire emissions, uncertainties in initial and boundary conditions for some species (e.g., other inorganic aerosols, CO, and O3) at surface and aloft, and some missing/inactivated model treatments for this application (e.g., chlorine chemistry and secondary organic aerosol formation). Major differences in the results among the three gas/particle mass transfer approaches occur over coastal areas, where EQUI predicts higher PM2.5 than HYBR and KINE due to improperly redistributing condensed nitrate from chloride depletion process to fine PM mode. The net direct, semi‐direct, and indirect effects of PM2.5 decrease domainwide shortwave radiation by 11.2–14.4 W m−2 (or 4.1–5.6%) and near‐surface temperature by 0.06–0.14°C (or 0.2–0.4%), lead to 125 to 796 cm−3 cloud condensation nuclei at a supersaturation of 0.1%, produce cloud droplet numbers as high as 2064 cm−3, and reduce domainwide mean precipitation by 0.22–0.59 mm day−1.}, number={D18}, journal={Journal of Geophysical Research}, publisher={American Geophysical Union (AGU)}, author={Zhang, Yang and Pan, Ying and Wang, Kai and Fast, Jerome D. and Grell, Georg A.}, year={2010}, month={Sep} }
 @article{oshima_koike_zhang_kondo_2009, title={Aging of black carbon in outflow from anthropogenic sources using a mixing state resolved model: 2. Aerosol optical properties and cloud condensation nuclei activities}, volume={114}, ISSN={0148-0227}, url={http://dx.doi.org/10.1029/2008JD011681}, DOI={10.1029/2008JD011681}, abstractNote={The Model of Aerosol Dynamics, Reaction, Ionization, and Dissolution with resolution of a mixing state of black carbon (BC) (referred to as MADRID‐BC hereinafter) has recently been developed to accurately simulate the time evolution of the entire BC mixing state. In this study, we apply MADRID‐BC to evaluate the influence of changes in BC mixing state on aerosol optical properties and cloud condensation nuclei (CCN) activities in air parcels horizontally transported out from an urban area in Japan within the planetary boundary layer (PBL) over the ocean. The evaluation shows that the coatings on BC particles enhance light absorption at a wavelength of 550 nm by 38% in air leaving the source region and by 59% after transport over the ocean for half a day. When the model treats aerosols using the conventional size‐resolved sectional representation that does not resolve BC mixing states, the simulated absorption coefficients and single scattering albedos are greater by 35–44% and smaller by 7–13%, respectively, than those from a simulation that resolves the BC mixing state. These results indicate that it is essential to take into account BC‐free particles in atmospheric models for accurate prediction of aerosol optical properties, because the conventional representation cannot separately treat BC‐containing and BC‐free particles in each size section. The evaluation also shows that BC‐containing particles having 55% and 83% of the BC mass can act as CCN at a supersaturation of 0.05% when they leave the source region and after transport for half a day, respectively. These results suggest the importance of the uplifting of BC particles from the PBL near source regions for their efficient long‐range transport in the free troposphere. Results from comparisons with aerosol optical measurements conducted during various campaigns, such as the Asian Aerosol Characterization Experiment (ACE Asia) and the Indian Ocean Experiment (INDOEX), suggest that MADRID‐BC simulations can capture general features of aerosol optical properties in outflow from anthropogenic sources.}, number={D18}, journal={Journal of Geophysical Research}, publisher={American Geophysical Union (AGU)}, author={Oshima, N. and Koike, M. and Zhang, Y. and Kondo, Y.}, year={2009}, month={Sep} }
 @article{oshima_koike_zhang_kondo_moteki_takegawa_miyazaki_2009, title={Aging of black carbon in outflow from anthropogenic sources using a mixing state resolved model: Model development and evaluation}, volume={114}, ISSN={0148-0227}, url={http://dx.doi.org/10.1029/2008JD010680}, DOI={10.1029/2008JD010680}, abstractNote={The mixing state of black carbon (BC) aerosols, namely, the degree to which BC particles are coated with other aerosol components, has been recognized as important for evaluating aerosol radiative forcing. In order to resolve the BC mixing state explicitly in model simulations, a two‐dimensional aerosol representation, in which aerosols are given for individual particle diameters and BC mass fractions, is introduced. This representation was incorporated into an aerosol module, the Model of Aerosol Dynamics, Reaction, Ionization, and Dissolution (MADRID), and a new box model, MADRID‐BC, was developed. MADRID‐BC can accurately simulate changes in the entire BC mixing state resulting from condensation/evaporation processes. Aircraft observations conducted in March 2004 show that the mass fraction of thickly coated BC particles increased in air horizontally transported out from an urban area in Japan over the ocean. MADRID‐BC generally reproduces this feature well when observed bulk aerosol concentrations are used as constraints. The model simulations in this particular case show that for particles with BC core diameters of 100–200 nm, the particle diameters, including both core and coating materials, had already increased by a factor of 1.6 on average when they left the source region and by as large as a factor of 1.9 of the BC core diameters after their transport over the ocean for a half day. The model simulations also show that 58% of the total condensed mass was partitioned onto BC‐free particles during transport, indicating their importance for the BC mixing state. Although the model simulations are applied to a limited number of the observations in this study, they clearly show the time evolution of the coating thicknesses of BC‐containing particles, which is necessary for calculating aerosol optical properties and cloud condensation nuclei activities.}, number={D6}, journal={Journal of Geophysical Research}, publisher={American Geophysical Union (AGU)}, author={Oshima, N. and Koike, M. and Zhang, Y. and Kondo, Y. and Moteki, N. and Takegawa, N. and Miyazaki, Y.}, year={2009}, month={Mar} }
 @article{vijayaraghavan_zhang_seigneur_karamchandani_snell_2009, title={Export of reactive nitrogen from coal-fired power plants in the U.S.: Estimates from a plume-in-grid modeling study}, volume={114}, ISSN={0148-0227}, url={http://dx.doi.org/10.1029/2008JD010432}, DOI={10.1029/2008JD010432}, abstractNote={The export of reactive nitrogen (nitrogen oxides and their oxidation products, collectively referred to as NOy) from coal‐fired power plants in the U.S. to the rest of the world could have a significant global contribution to ozone. Traditional Eulerian gridded air quality models cannot characterize accurately the chemistry and transport of plumes from elevated point sources such as power plant stacks. A state‐of‐the‐science plume‐in‐grid (PinG) air quality model, a reactive plume model embedded in an Eulerian gridded model, is used to estimate the export of NOy from 25 large coal‐fired power plants in the U.S. (in terms of NOx and SO2 emissions) in July 2001 to the global atmosphere. The PinG model used is the Community Multiscale Air Quality Model with Advanced Plume Treatment (CMAQ‐APT). A benchmark simulation with only the gridded model, CMAQ, is also conducted for comparison purposes. The simulations with and without advanced plume treatment show differences in the calculated export of NOy from the 25 plants considered reflecting the effect of using a detailed and explicit treatment of plume transport and chemistry. The advanced plume treatment results in 31% greater simulated export of NOy compared to the purely grid‐based modeling approach. The export efficiency of NOy (the fraction of NOy emitted that is exported) is predicted to be 21% without APT and 27% with APT. When considering only export through the eastern boundary across the Atlantic, CMAQ‐APT predicts that the export efficiency is 24% and that 2% of NOy is exported as NOx, 49% as inorganic nitrate, and 25% as PAN. These results are in reasonably good agreement with an analysis reported in the literature of aircraft measurements over the North Atlantic.}, number={D4}, journal={Journal of Geophysical Research}, publisher={American Geophysical Union (AGU)}, author={Vijayaraghavan, Krish and Zhang, Yang and Seigneur, Christian and Karamchandani, Prakash and Snell, Hilary E.}, year={2009}, month={Feb} }
 @inbook{renner_zhang_2009, title={Interactions between air quality and climate change}, ISBN={9789048138104 9789048138128}, ISSN={1874-6519 1874-6543}, url={http://dx.doi.org/10.1007/978-90-481-3812-8_6}, DOI={10.1007/978-90-481-3812-8_6}, booktitle={Air Pollution Modeling and its Application XX}, publisher={Springer Netherlands}, author={Renner, E. and Zhang, Y.}, year={2009}, month={Dec}, pages={479–518} }
 @article{wang_zhang_jang_phillips_wang_2009, title={Modeling intercontinental air pollution transport over the trans-Pacific region in 2001 using the Community Multiscale Air Quality modeling system}, volume={114}, ISSN={0148-0227}, url={http://dx.doi.org/10.1029/2008JD010807}, DOI={10.1029/2008JD010807}, abstractNote={The Community Multiscale Air Quality modeling system is used to study the intercontinental transport of air pollution across the Pacific region. Baseline simulations are conducted for January, April, July, and October 2001 at a 108 km horizontal grid resolution. A sensitivity simulation is conducted for April 2001 to study the impact of Asian anthropogenic emissions on the United States's air quality. Process analysis is conducted to study pollutant formation and transport and to quantify the relative contributions of atmospheric processes to ozone (O3) and fine particulate matter (PM2.5). Model simulations are evaluated with available surface, aircraft, and satellite observations. Simulated meteorology basically captures the synoptic pattern, but precipitation amounts are significantly underpredicted. Most of the PM2.5 components are overestimated over the United States and most gases are underestimated over east Asia. Simulated NO2 and CO columns agree well with satellite observations. Aerosol optical depths and tropospheric O3 residuals are underpredicted, especially in July. The simulated horizontal fluxes and process analyses show that the transport in the lower free troposphere followed by a large‐scale subsidence over the United States provides a major Asian pollution export pathway for most pollutants, while the transport in the planetary boundary layer also plays an important role, especially for CO, O3, PM2.5, and SO42−. The background concentrations of O3 and SO42− in the western United States can increase by ∼1 ppb (∼2.5%) and 0.4 μg m−3 (∼20%) in monthly average, up to 2.5 ppb and 1.0 μg m−3 in daily average, respectively, due to the Asian emissions in April.}, number={D4}, journal={Journal of Geophysical Research}, publisher={American Geophysical Union (AGU)}, author={Wang, Kai and Zhang, Yang and Jang, Carey and Phillips, Sharon and Wang, Binyu}, year={2009}, month={Feb} }
 @article{zhang_wen_wang_vijayaraghavan_jacobson_2009, title={Probing into regional O3and particulate matter pollution in the United States: 2. An examination of formation mechanisms through a process analysis technique and sensitivity study}, volume={114}, ISSN={0148-0227}, url={http://dx.doi.org/10.1029/2009JD011900}, DOI={10.1029/2009JD011900}, abstractNote={Following a comprehensive model evaluation in part 1, this part 2 paper describes results from 1 year process analysis and a number of sensitivity simulations using the Community Multiscale Air Quality (CMAQ) modeling system aimed to understand the formation mechanisms of O3 and PM2.5, their impacts on global environment, and implications for pollution control policies. Process analyses show that the most influential processes for O3 in the planetary boundary layer (PBL) are vertical and horizontal transport, gas‐phase chemistry, and dry deposition and those for PM2.5 are primary PM emissions, horizontal transport, PM processes, and cloud processes. Exports of O3 and Ox from the U.S. PBL to free troposphere occur primarily in summer and at a rate of 0.16 and 0.65 Gmoles day−1, respectively. In contrast, export of PM2.5 is found to occur during all seasons and at rates of 25.68–34.18 Ggrams day−1, indicating a need to monitor and control PM2.5 throughout the year. Among nine photochemical indicators examined, the most robust include PH2O2/PHNO3, HCHO/NOy, and HCHO/NOz in winter and summer, H2O2/(O3 + NO2) in winter, and NOy in summer. They indicate a VOC‐limited O3 chemistry in most areas in winter, but a NOx‐limited O3 chemistry in most areas except for major cities in April–November, providing a rationale for nationwide NOx emission control and integrated control of NOx and VOCs emissions for large cities during high O3 seasons (May–September). For sensitivity of PM2.5 to its precursors, the adjusted gas ratio provides a more robust indicator than that without adjustment, especially for areas with insufficient sulfate neutralization in winter. NH4NO3 can be formed in most of the domain. Integrated control of emissions of PM precursors such as SO2, NOx, and NH3 are necessary for PM2.5 attainment. Among four types of VOCs examined, O3 formation is primarily affected by isoprene and low molecular weight anthropogenic VOCs, and PM2.5 formation is affected largely by terpenes and isoprene. Under future emission scenarios, surface O3 may increase in summer; surface PM2.5 may increase or decrease. With 0.71°C increase in future surface temperatures in summer, surface O3 may increase in most of the domain and surface PM2.5 may decrease in the eastern U.S. but increase in the western U.S.}, number={D22}, journal={Journal of Geophysical Research}, publisher={American Geophysical Union (AGU)}, author={Zhang, Yang and Wen, Xin-Yu and Wang, Kai and Vijayaraghavan, Krish and Jacobson, Mark Z.}, year={2009}, month={Nov} }
 @article{zhang_vijayaraghavan_wen_snell_jacobson_2009, title={Probing into regional ozone and particulate matter pollution in the United States: 1. A 1 year CMAQ simulation and evaluation using surface and satellite data}, volume={114}, ISSN={0148-0227}, url={http://dx.doi.org/10.1029/2009JD011898}, DOI={10.1029/2009JD011898}, abstractNote={As part 1 in a series of papers describing long‐term simulations using the Community Multiscale Air Quality (CMAQ) modeling system and subsequent process analyses and sensitivity simulations, this paper presents a comprehensive model evaluation for the full year of 2001 over the continental U.S. using both ground‐based and satellite measurements. CMAQ is assessed for its ability to reproduce concentrations and long‐term trends of major criteria pollutants such as surface ozone (O3) and fine particulate matter (PM2.5) and related variables such as indicator species, wet deposition fluxes, and column mass abundances of carbon monoxide (CO), nitrogen oxides (NO2), tropospheric ozone residuals (TORs), and aerosol optical depths (AODs). The domain‐wide and site‐specific evaluation of surface predictions shows an overall satisfactory performance in terms of normalized mean biases for annual mean maximum 1 h and 8 h average O3 mixing ratios (−11.6 to 0.1% and −4.6 to 3.0%, respectively), 24 h average concentrations of PM2.5 (4.2–35.3%), sulfate (−13.0 to 43.5%), and organic carbon (OC) (−37.6 to 24.8%), and wet deposition fluxes (−13.3 to 31.6%). Larger biases, however, occur in the concentrations and wet deposition fluxes of ammonium and nitrate domain‐wide and in the concentrations of PM2.5, sulfate, black carbon, and OC at some urban/suburban sites. The reasons for such model biases may be errors in emissions, chemistry, aerosol processes, or meteorology. The evaluation of column mass predictions shows a good model performance in capturing the seasonal variations and magnitudes of column CO and NO2, but relatively poor performance in reproducing observed spatial distributions and magnitudes of TORs for winter and spring and those of AODs in all seasons. Possible reasons for the poor column predictions include the underestimates of emissions, inaccurate upper layer boundary conditions, lack of model treatments of sea salt and dust, and limitations and uncertainties in satellite data.}, number={D22}, journal={Journal of Geophysical Research}, publisher={American Geophysical Union (AGU)}, author={Zhang, Yang and Vijayaraghavan, Krish and Wen, Xin-Yu and Snell, Hilary E. and Jacobson, Mark Z.}, year={2009}, month={Nov} }
 @misc{zhang_vijayaraghavan_wen_snell_jacobson_2009, title={Probing into regional ozone and particulate matter pollution in the United States: 1. A 1 year CMAQ simulation and evaluation using surface and satellite data}, volume={114}, journal={Journal of Geophysical Research. Atmospheres (Online)}, author={Zhang, Y. and Vijayaraghavan, K. and Wen, X. Y. and Snell, H. E. and Jacobson, M. Z.}, year={2009} }
 @article{liu_zhang_2008, title={A computationally-efficient secondary organic aerosol module for three-dimensional air quality models}, volume={8}, ISSN={["1680-7324"]}, DOI={10.5194/acp-8-3985-2008}, abstractNote={Abstract. Accurately simulating secondary organic aerosols (SOA) in three-dimensional (3-D) air quality models is challenging due to the complexity of the physics and chemistry involved and the high computational demand required. A computationally-efficient yet accurate SOA module is necessary in 3-D applications for long-term simulations and real-time air quality forecasting. A coupled gas and aerosol box model (i.e., 0-D CMAQ-MADRID 2) is used to optimize relevant processes in order to develop such a SOA module. Solving the partitioning equations for condensable volatile organic compounds (VOCs) and calculating their activity coefficients in the multicomponent mixtures are identified to be the most computationally-expensive processes. The two processes can be speeded up by relaxing the error tolerance levels and reducing the maximum number of iterations of the numerical solver for the partitioning equations for organic species; conditionally activating organic-inorganic interactions; and parameterizing the calculation of activity coefficients for organic mixtures in the hydrophilic module. The optimal speed-up method can reduce the total CPU cost by up to a factor of 31.4 from benchmark under the rural conditions with 2 ppb isoprene and by factors of 10–71 under various test conditions with 2–10 ppb isoprene and >40% relative humidity while maintaining ±15% deviation. These speed-up methods are applicable to other SOA modules that are based on partitioning theories.
                    }, number={14}, journal={ATMOSPHERIC CHEMISTRY AND PHYSICS}, author={Liu, P. and Zhang, Y.}, year={2008}, pages={3985–3998} }
 @article{hu_zhang_jacobson_chan_2008, title={Coupling and evaluating gas/particle mass transfer treatments for aerosol simulation and forecast}, volume={113}, ISSN={["2169-8996"]}, DOI={10.1029/2007jd009588}, abstractNote={Simulating gas/particle mass transfer in three‐dimensional (3‐D) air quality models (AQMs) represents one of the major challenges for both hindcasting and forecasting. The lack of an efficient yet accurate gas/particle mass transfer treatment for aerosol simulation and forecast in 3‐D AQMs warrants its development, improvement, and evaluation. In this paper, several condensation/evaporation schemes (e.g., the Bott, Trajectory‐Grid (T‐G), Walcek, and analytical predictor of condensation (APC)) are first tested in a condensation‐only case. The APC and Walcek schemes are shown to be more accurate than the Bott and T‐G schemes. The Walcek and the APC schemes are then incorporated into the Model of Aerosol Dynamics, Reaction, Ionization, and Dissolution (MADRID) to solve the gas/particle mass transfer process explicitly. The test simulations with MADRID are initialized with measurements available from three sites with representative meteorological and emission characteristics. The results are evaluated using benchmark based on the kinetic approach with 500‐section for all cases and available measurements from two sites. The box MADRID tests have shown that the bulk equilibrium approach fails to predict the distribution of semivolatile species (e.g., ammonium, chloride, and nitrate) because of the equilibrium and internal mixture assumptions. The hybrid approach exhibits the same problem for some cases as the bulk equilibrium approach since it assumes bulk equilibrium for fine particles. The kinetic approaches (including the APC and Walcek schemes for the condensation/evaporation equations) predict the most accurate solutions. Among all approaches tested, the bulk equilibrium approach is the most computationally efficient, and the kinetic/Walcek scheme provides an accurate solution but is the slowest due to its requirement for a small time step. Overall, the kinetic/APC and hybrid/APC schemes are attractive for 3‐D applications in terms of both accuracy and computational efficiency.}, number={D11}, journal={JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES}, author={Hu, Xiao-Ming and Zhang, Yang and Jacobson, Mark Z. and Chan, Chak K.}, year={2008}, month={Jun} }
 @article{queen_zhang_gilliam_pleim_2008, title={Examining the sensitivity of MM5-CMAQ predictions to explicit microphysics schemes and horizontal grid resolutions, Part I - Database, evaluation protocol, and precipitation predictions}, volume={42}, ISSN={["1352-2310"]}, DOI={10.1016/j.atmosenv.2007.12.067}, abstractNote={Wet deposition of chemical species is one of the most difficult processes to simulate in three-dimensional (3-D) air quality models, due to the complex interplay among meteorology, cloud, and atmospheric chemistry. Different cloud microphysical treatments and horizontal grid resolutions in 3-D models can directly affect simulated clouds, precipitation, and wet deposition. In this study, the performance and sensitivity of the simulated precipitation, concentrations, and wet deposition to different explicit microphysics schemes and horizontal grid resolutions are evaluated for August and December 2002 for a domain centered over North Carolina (NC). Four explicit microphysics schemes in MM5 are examined: Reisner 1 (R1), Reisner 2 (R2), Dudhia (SI), and Hsie (WR). The precipitation evaluation indicates that monthly-average precipitation amounts are underpredicted by all schemes in both August and December at all sites except for the R1 August simulation that shows overpredictions at National Acid Deposition Program (NADP) sites. An increased sensitivity to microphysics schemes is found at locations in both the coastal plain and mountain regions in August and the mountain region in December. The differences in simulation results in August and December are mainly attributed to seasonal differences in dominant meteorological forcing (mesoscale vs. synoptic, respectively). Among the schemes tested, R2 and SI give the best overall performance in predicting precipitation for both months. These findings are applicable for NC and neighboring states with similar meteorological and emission characteristics.}, number={16}, journal={ATMOSPHERIC ENVIRONMENT}, author={Queen, Ashley and Zhang, Yang and Gilliam, Robert and Pleim, Jonathan}, year={2008}, month={May}, pages={3842–3855} }
 @article{queen_zhang_2008, title={Examining the sensitivity of MM5-CMAQ predictions to explicit microphysics schemes and horizontal grid resolutions, Part II - PM concentrations and wet deposition predictions}, volume={42}, DOI={10.1016/j.atmosenv.2007.12.066}, abstractNote={This part II paper first evaluates the simulated concentrations and wet deposition amounts of NH4+, NO3−, and SO42− using observations from several networks, then examines their sensitivities to four explicit microphysics schemes: Reisner 1 (R1), Reisner 2 (R2), Dudhia simple ice (SI), and Hsie warm rain (WR). For baseline simulation with R1, the concentrations of NH4+, NO3−, and SO42− are underpredicted in August. Concentrations of SO42− are underpredicted and those of NH4+ and NO3− are overpredicted in December. The wet deposition amounts of NH4+ and SO42− are overpredicted but those of NO3− are underpredicted in August. The wet deposition amounts of NO3− and NH4+ are overpredicted but those of SO42− are underpredicted in December. The simulated wet deposition amounts are sensitive to various schemes, which are most evident in December, with the best results for NH4+ and NO3− by WR and the best for SO42− by SI. A correlation exists between wet deposition amounts and precipitation in both months, with stronger magnitudes in August. Conversely, in December, as the correlation with precipitation decreases, that with aqueous-phase concentrations increases. These results are consistent with meteorological conditions since the summer convective precipitation events having larger intensities and therefore the meteorological forcing is expected to dominate August correlations. As these intensities decrease in December, the chemical forcing becomes more influential.}, number={16}, journal={Atmospheric Environment}, author={Queen, A. and Zhang, Y.}, year={2008}, pages={3856–3868} }
 @article{queen_zhang_2008, title={Examining the sensitivity of MM5-CMAQ predictions to explicit microphysics schemes and horizontal grid resolutions, Part III - The impact of horizontal grid resolution}, volume={42}, ISSN={["1873-2844"]}, DOI={10.1016/j.atmosenv.2008.02.035}, abstractNote={Examination of model sensitivity to horizontal grid resolutions can help identify optimal compromise in accuracy and computational efficiency for regulatory and research-grade applications of 3-D atmospheric models. In this Part III paper, the performance and sensitivity of simulated precipitation and wet deposition amounts by the MM5/CMAQ model to three horizontal grid resolutions (4-, 12-, and 36-km) are evaluated over North Carolina (NC). In contrast with simulated O3, PM2.5, and some PM2.5 species such as NH4+, simulated precipitation and wet deposition amounts are quite sensitive to grid resolutions. Compared with results at coarser resolutions, simulated precipitation amounts are lower in both August and December at 4-km, with the largest sensitivities to grid resolutions occurring in mountain and coastal regions of NC. For wet deposition predictions, the model performs the best for NO3− at 4-km and for NH4+ and SO42− at 12-km in August, but the best for NH4+ and NO3− at 36-km and for SO42− at 4-km in December. Such sensitivities and lack of clear trends in model performance at various resolutions can be attributed to seasonalities in meteorology and differences in characteristics of land use, emissions and concentrations of PM precursors, as well as nonlinear responses of chemistry and meteorology to grid resolutions. The overall performance trends demonstrate a high sensitivity in precipitation and wet deposition predictions over complex terrain and the fact that higher grid resolution does not always lead to improved model performance.}, number={16}, journal={ATMOSPHERIC ENVIRONMENT}, author={Queen, Ashley and Zhang, Yang}, year={2008}, month={May}, pages={3869–3881} }
 @article{zhang_hu_leung_gustafson_2008, title={Impacts of regional climate change on biogenic emissions and air quality}, volume={113}, ISSN={["2169-8996"]}, DOI={10.1029/2008jd009965}, abstractNote={Regional air quality simulations are conducted at a horizontal grid resolution of 36 km for four summers (2001, 2002, 2051, and 2052) to examine the sensitivity of air quality to potential regional climate change in the United States. In response to the predicted warmer climate in 2051/2052, the emissions of isoprene and terpene increase by 20–92% and 20–56%, respectively, over most of the domain. Surface O3 increases by up to 19–20%. Such increases are largely driven by changes in temperature, solar radiation, and cloud fraction over most of the domain. PM2.5, its compositions, and visibility exhibit an overall negative sensitivity (decrease by up to 40%), resulting from the competition of the negative temperature effect and positive emission/temperature effects. While the response of dry deposition is governed by the negative sensitivity of surface resistances, that of wet deposition is either positive or negative, depending on the relative dominancy of changes in PM2.5 and precipitation. Overall the net climatic effect due to changes in climatic variables alone dominates changes in O3, PM2.5, and wet and total deposition, and the net biogenic emission effect due to changes in biogenic emissions alone as a result of climate change is important for isoprene, organic matter, visibility, and dry deposition over several regions. Models that do not include secondary organic aerosol formation from isoprene may underestimate by at least 20% of the responses of organic aerosols to future climate changes over many areas of the modeling domain. Both regional climate and air quality exhibit interannual variability, particularly in temperature, isoprene emissions, and PM2.5 concentrations, indicating a need for long‐term simulations to predict future air quality. Compared with results from global models, stronger regional climate change signals may cause projected local impacts of climate change that are stronger or even different in sign.}, number={D18}, journal={JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES}, author={Zhang, Yang and Hu, Xiao-Ming and Leung, L. Ruby and Gustafson, William I., Jr.}, year={2008}, month={Sep} }
 @article{goetz_aneja_zhang_2008, title={Measurement, analysis, and modeling of fine particulate matter in eastern North Carolina}, volume={58}, ISSN={["1047-3289"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-53149087232&partnerID=MN8TOARS}, DOI={10.3155/1047-3289.58.9.1208}, abstractNote={Abstract An analysis of fine particulate data in eastern North Carolina was conducted to investigate the impact of the hog industry and its emissions of ammonia into the atmosphere. The fine particulate data are simulated using ISORROPIA, an equilibrium thermodynamic model that simulates the gas and aerosol equilibrium of inorganic atmospheric species. The observational data analyses show that the major constituents of fine particulate matter (PM2.5) are organic carbon, elemental carbon, sulfate, nitrate, and ammonium. The observed PM2.5 concentration is positively correlated with temperature but anticor-related with wind speed. The correlation between PM2.5 and wind direction at some locations suggests an impact of ammonia emissions from hog facilities on PM2.5 formation. The modeled results are in good agreement with observations, with slightly better agreement at urban sites than at rural sites. The predicted total inorganic particulate matter (PM) concentrations are within 5% of the observed values under conditions with median initial total PM species concentrations, median relative humidity (RH), and median temperature. Ambient conditions with high PM precursor concentrations, low temperature, and high RH appear to favor the formation of secondary PM.}, number={9}, journal={JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION}, author={Goetz, Stephen and Aneja, Viney P. and Zhang, Yang}, year={2008}, month={Sep}, pages={1208–1214} }
 @article{zhang_wu_krishnan_wang_queen_aneja_arya_2008, title={Modeling agricultural air quality: Current status, major challenges, and outlook}, volume={42}, ISSN={["1873-2844"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-41549095063&partnerID=MN8TOARS}, DOI={10.1016/j.atmosenv.2007.01.063}, abstractNote={Agricultural air quality is an important emerging area of atmospheric sciences that represents significant challenges in many aspects of research including measurements, modeling, regulations, emission control, and operation managements. This work presents a review of current status, major challenges, and future research needs and opportunities of several important aspects of agricultural air quality modeling including chemical species, concentration and deposition measurements for model verification, emission inventories, major physical and chemical processes, model application and evaluation, and policy implications.}, number={14}, journal={ATMOSPHERIC ENVIRONMENT}, author={Zhang, Yang and Wu, Shiang-Yuh and Krishnan, Srinath and Wang, Kai and Queen, Ashley and Aneja, Viney P. and Arya, S. Pal}, year={2008}, month={Apr}, pages={3218–3237} }
 @article{wu_hu_zhang_aneja_2008, title={Modeling atmospheric transport and fate of ammonia in North Carolina - Part II: Effect of ammonia emissions on fine particulate matter formation}, volume={42}, ISSN={["1873-2844"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-41449110003&partnerID=MN8TOARS}, DOI={10.1016/j.atmosenv.2007.04.022}, abstractNote={Accurate estimates of ammonia (NH3) emissions are needed for reliable predictions of fine particulate matter (PM2.5) by air quality models (AQMs), but the current estimates contain large uncertainties in the temporal and spatial distributions of NH3 emissions. In this study, the US EPA Community Multiscale Air Quality (CMAQ) modeling system is applied to study the contributions of the agriculture–livestock NH3 (AL-NH3) emissions to the concentration of PM2.5 and the uncertainties in the total amount and the temporal variations of NH3 emissions and their impact on the formation of PM2.5 for August and December 2002. The sensitivity simulation results show that AL-NH3 emissions contribute significantly to the concentration of PM2.5, NH4+, and NO3−; their contributions to the concentrations of SO42− are relatively small. The impact of NH3 emissions on PM2.5 formation shows strong spatial and seasonal variations associated with the meteorological conditions and the ambient chemical conditions. Increases in NH3 emissions in August 2002 resulted in >10% increases in the concentrations of NH4+ and NO3−; reductions in NH3 emissions in December 2002 resulted in >20% decreases in their concentrations. The large changes in species concentrations occur downwind of the high NH3 emissions where the ambient environment is NH3-poor or neutral. The adjustments in NH3 emissions improve appreciably the model predictions of NH4+ and NO3− both in August and December, but resulted in negligible improvements in PM2.5 in August and a small improvement in December, indicating that other factors (e.g., inaccuracies in meteorological predictions, emissions of other primary species, aerosol treatments) might be responsible for model biases in PM2.5.}, number={14}, journal={ATMOSPHERIC ENVIRONMENT}, author={Wu, Shiang-Yuh and Hu, Jian-Lin and Zhang, Yang and Aneja, Viney P.}, year={2008}, month={Apr}, pages={3437–3451} }
 @article{wu_krishnan_zhang_aneja_2008, title={Modeling atmospheric transport and fate of ammonia in North Carolina-Part I: Evaluation of meteorological and chemical predictions}, volume={42}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-41449096822&partnerID=MN8TOARS}, DOI={10.1016/j.atmosenv.2007.04.031}, abstractNote={The atmospheric transport and fate of ammonia (NH3) depend on both meteorological and chemical conditions once it is emitted into the atmosphere. The largest source contributing to NH3 emission is the agricultural production, in particular animal operation, in North Carolina (NC). In this study, three-dimensional numerical meteorological and air quality models are applied to study the transport and fate of NH3 in the atmosphere in an area in southeast US centered over NC. One summer and one winter month simulations with a 4-km horizontal grid were conducted to simulate the meteorological and chemical environments for the transport and transformation of the reduced nitrogen, NHx (=NH3+NH4+) and to examine its seasonal variations and interactions with other chemical species (e.g., ozone and fine particular matter, PM2.5). The model performance for simulated meteorology and air quality was evaluated against observations in terms of spatial distributions, temporal variations, and statistical trends. MM5/CMAQ gave an overall good performance for meteorological variables and O3 mixing ratios and a reasonably good performance for PM2.5. The simulations show that 10–40% of total NH3 was converted to NH4+ at/near source and 40–100% downwind in August, and the conversion rates were 20–50% at/near source and 50–98% downwind in December. While the 3-D atmospheric models demonstrate some skills in capturing synoptic meteorological patterns, diurnal variations of concentrations of oxidants and PM2.5, and regional transport and transformation of NHx, reproducing meteorological and chemical features at a local scale and the magnitudes of hourly concentrations of oxidants and PM2.5 remain challenging due to uncertainties in model inputs and treatments.}, number={14}, journal={Atmospheric Environment}, author={Wu, S.-Y. and Krishnan, S. and Zhang, Y. and Aneja, Viney}, year={2008}, pages={3419–3436} }
 @misc{zhang_2008, title={Online-coupled meteorology and chemistry models: history, current status, and outlook}, volume={8}, number={11}, journal={Atmospheric Chemistry and Physics}, author={Zhang, Y.}, year={2008}, pages={2895–2932} }
 @article{zhang_huang_henze_seinfeld_2007, title={Role of isoprene in secondary organic aerosol formation on a regional scale}, volume={112}, ISSN={["2169-8996"]}, DOI={10.1029/2007jd008675}, abstractNote={The role of isoprene as a source of secondary organic aerosol (SOA) is studied using laboratory‐derived SOA yields and the U.S. Environmental Protection Agency regional‐scale Community Multiscale Air Quality (CMAQ) modeling system over a domain comprising the contiguous United States, southern Canada, and northern Mexico. Isoprene is predicted to be a significant source of biogenic SOA, leading to increases up to 3.8 μg m−3 in the planetary boundary layer (PBL, defined as 0–2.85 km) and 0.44 μg m−3 in the free troposphere over that in the absence of isoprene. While the addition of isoprene to the class of SOA‐forming organics in CMAQ increases appreciably predicted fine‐particle organic carbon (OC2.5) in the eastern and southeastern U.S., total OC2.5 is still underpredicted in these regions. SOA formation is highly sensitive to the value of the enthalpy of vaporization of the SOA. The role of isoprene SOA is examined in a sensitivity study at values of 42 and 156 kJ mol−1; both are commonly used in 3‐D aerosol models. Prediction of ambient levels of SOA in atmospheric models remains a challenging problem because of the importance of emissions inventories for SOA‐forming organics, representation of gas phase atmospheric chemistry leading to semivolatile products, and treatment of the physics and chemistry of aerosol formation and removal.}, number={D20}, journal={JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES}, author={Zhang, Yang and Huang, Jian-Ping and Henze, Daven K. and Seinfeld, John H.}, year={2007}, month={Oct} }
 @article{zhang_liu_pun_seigneur_2006, title={A comprehensive performance evaluation of MM5-CMAQ for the Summer 1999 Southern Oxidants Study episode - Part I: Evaluation protocols, databases, and meteorological predictions}, volume={40}, ISSN={["1873-2844"]}, DOI={10.1016/j.atmosenv.2005.12.043}, abstractNote={A comprehensive model evaluation has been conducted for MM5-CMAQ for the period of 1–10 July 1999 of the Southern Oxidants Study episode with a coarse-grid horizontal spacing of 32-km and a nested fine-grid spacing of 8-km. Meteorological and chemical predictions from simulations with both grids are compared with observations from both routine monitoring networks (e.g., CASTNet, IMPROVE, and AIRS-AQS) and special studies (e.g., SOS99/SOS99NASH, SEARCH, and ARIES). In this Part I paper, five simulated meteorological variables (i.e., temperature, relative humidity (RH), wind speed, wind direction, and planetary boundary layer (PBL) height) are evaluated. While MM5 reproduces well the diurnal variations for temperature and RH, and the minimum temperatures at all sites, it tends to overpredict maximum temperatures and underpredict both maximum and minimum RHs on most days at most sites. MM5 predictions agree reasonably well for wind speeds but poorly for wind direction and the maximum mixing depths. The significant overpredictions in the PBL heights can be attributed to the positive biases of the maximum 2-m temperatures and to the Medium Range Forecast (MRF) model PBL scheme and the Oregon State University (OSU)-Land Surface Model used in the MM5 simulations. For wind speed/direction and the U- and V-component of the wind speed, the normalized mean bias (NMB) and the normalized mean bias factor (NMBF) are the most robust statistical measures because of the dominance of the extremely small observed values in the normalization for those variables.}, number={26}, journal={ATMOSPHERIC ENVIRONMENT}, author={Zhang, Yang and Liu, Ping and Pun, Betty and Seigneur, Christian}, year={2006}, month={Aug}, pages={4825–4838} }
 @article{zhang_liu_queen_misenis_pun_seigneur_wu_2006, title={A comprehensive performance evaluation of MM5-CMAQ for the Summer 1999 Southern Oxidants Study episode-  Part II: Gas and aerosol predictions}, volume={40}, DOI={10.1016/j.atmonsenv.2005.12.048}, number={26}, journal={Atmospheric Environment}, author={Zhang, Y. and Liu, P. and Queen, A. and Misenis, C. and Pun, B. and Seigneur, C. and Wu, S. Y.}, year={2006}, pages={4839–4855} }
 @article{zhang_liu_queen_misenis_pun_seigneur_wu_2006, title={A comprehensive performance evaluation of MM5-CMAQ for the Summer 1999 Southern Oxidants Study episode—Part II: Gas and aerosol predictions}, volume={40}, ISSN={1352-2310}, url={http://dx.doi.org/10.1016/j.atmosenv.2005.12.048}, DOI={10.1016/j.atmosenv.2005.12.048}, abstractNote={Gas and aerosol predictions from CMAQ simulations with horizontal grid spacings of 8- and 32-km are evaluated against available observations from CASTNet, IMPROVE, AIRS-AQS, SOS99/SOS99NASH, SEARCH, and ARIES for the southeastern US for the period of 1–10 July 1999. The predictions evaluated in this work include mixing ratios of O3 (hourly, maximum 1-h, and 8-h average), NOx, HNO3, NOy, and mass concentrations of PM10, PM2.5, and PM2.5 components. Our evaluation has shown that CMAQ tends to underpredict maximum 1-h O3 mixing ratios on high O3 days at some sites. It overpredicts the maximum and minimum hourly O3 mixing ratios for most low O3 days, the daytime and nighttime hourly, and the maximum 8-h average O3 mixing ratios on most days at all sites. The model performance for hourly O3 mixing ratios generally meets EPA's criteria but deteriorates for maximum 1- and 8-h average O3 mixing ratios. CMAQ underpredicts the mass concentrations of PM10, PM2.5, and PM2.5 composition and fails to reproduce their temporal variations (except for sulfate). Largest underpredictions occur for organic matter (OM2.5) and nitrate2.5 among all PM components. These underpredictions and overpredictions may be caused by inaccurate meteorological predictions (e.g., the PBL height, wind speed/direction, vertical mixing, temperature, and relative humidity) and boundary conditions for chemical species (e.g., O3), underestimation in emissions (e.g., NOx, NH3, and primary OM), as well as uncertainties in model assumptions and treatments in aerosol chemistry and microphysics.}, number={26}, journal={Atmospheric Environment}, publisher={Elsevier BV}, author={Zhang, Yang and Liu, Ping and Queen, Ashley and Misenis, Chris and Pun, Betty and Seigneur, Christian and Wu, Shiang-Yuh}, year={2006}, month={Aug}, pages={4839–4855} }
 @article{zhang_liu_pun_seigneur_2006, title={A comprehensive performance evaluation of MM5-CMAQ for the summer 1999 southern oxidants study episode, Part III: Diagnostic and mechanistic evaluations}, volume={40}, DOI={10.1016/j.atmonsenv.2005.12.046}, number={26}, journal={Atmospheric Environment}, author={Zhang, Y. and Liu, P. and Pun, B. and Seigneur, C.}, year={2006}, pages={4856–4873} }
 @article{zhang_liu_pun_seigneur_2006, title={A comprehensive performance evaluation of MM5-CMAQ for the summer 1999 southern oxidants study episode, Part III: Diagnostic and mechanistic evaluations}, volume={40}, ISSN={1352-2310}, url={http://dx.doi.org/10.1016/j.atmosenv.2005.12.046}, DOI={10.1016/j.atmosenv.2005.12.046}, abstractNote={As Part III of a comprehensive evaluation of CMAQ for the summer 1999 Southern Oxidants Study episode, the observed number (N), volume (V), surface area (S), and size distributions of accumulation-mode particles during the Aerosol Research Inhalation Epidemiological Study (ARIES) are used to evaluate CMAQ's capability in reproducing PM size distributions. CMAQ underpredicts V, S, and geometric number mean diameter (by a factor of 1.24–1.54), and overpredicts N, geometric standard deviation, and geometric volume mean diameter (by a factor of 1.46–2.2) on most days. In addition to inaccurate meteorology and emissions, insufficient condensational growth of PM and uncertainty in the initial size distribution may contribute to the underpredictions in V and S. An overestimation of the PM number emission rates (by a factor of 3–5.3) and several other model assumptions/treatments may contribute to the PM number overpredictions. Among the factors that we studied, the floor value of Kzz, the boundary conditions (BCONs) of O3, the emissions of gaseous precursors such as NOx and NH3 and primary PM species such as POM, and the assumed initial PM size distribution and emission fractions have been identified to be the most influential factors that affect the overall model performance. Sensitivity simulations with a floor value of Kzz of 0.1 cm2 s−1, adjusted emissions of NOx, NH3, and POM, and adjusted initial PM size distribution and emission fractions provide moderate-to-significant improvements. Further investigation into the uncertainties/deficiencies in model treatments for PM such as gas-to-particle mass transfer will identify additional causes for discrepancies between observations and predictions.}, number={26}, journal={Atmospheric Environment}, publisher={Elsevier BV}, author={Zhang, Yang and Liu, Ping and Pun, Betty and Seigneur, Christian}, year={2006}, month={Aug}, pages={4856–4873} }
 @article{zhang_2005, title={Evaluation of three probing techniques in a three-dimensional air quality model}, volume={110}, ISSN={0148-0227}, url={http://dx.doi.org/10.1029/2004JD005248}, DOI={10.1029/2004JD005248}, abstractNote={Probing techniques are useful to provide diagnostic evaluations of air quality models and to indicate the responses of model predictions to changes in emissions. Three probing tools are available in a three‐dimensional air quality model, CAMx: the Decoupled Direct Method (DDM), the Ozone Source Attribution Technology (OSAT), and Process Analysis (PA). These tools are evaluated in terms of consistency, complementarity, accuracy and robustness, and computational requirements using the 7–15 July 1995 O3 episode over the eastern United States. The NOx‐ versus VOC‐sensitivity of O3 chemistry and relative role of chemistry and transport predicted by the three tools are qualitatively consistent, except that OSAT predicts an NOx‐limited O3 chemistry at a few locations where both DDM and PA predict a VOC‐sensitive O3 chemistry. DDM and OSAT agree well on the top 10 contributors to O3 formation, but they predict different rankings, with greater importance given to biogenic VOC emissions by DDM and greater importance given to surface anthropogenic NOx emissions by OSAT. The major difference in the DDM and OSAT predictions on the relative impact of sources is that DDM predicts both positive and negative sensitivities whereas OSAT always predicts positive contributions. Compared to the single‐perturbation method (brute force method), DDM predicts accurate model responses under the 25% VOC or NOx emission reduction scenarios but inaccurate results under the 75% NOx emission reduction scenario. OSAT predicts accurate model responses under the 25% VOC emission reduction scenario, but inaccurate responses under the 25% and 75% NOx emission reduction scenarios. While these tools provide valuable and complementary information regarding O3 formation, each of them has limitations in terms of its design and application for the design of emission control strategies. DDM is suitable for such an application for small‐to‐moderate emission reductions of <40%. OSAT leads to incorrect results for VOC‐limited areas because it does not account for the titration/inhibition effect of NOx and/or VOC. PA provides an in‐depth understanding of the processes involved in controlling O3 formation locally. It can be used to understand some of the differences between the results of OSAT and DDM.}, number={D2}, journal={Journal of Geophysical Research}, publisher={American Geophysical Union (AGU)}, author={Zhang, Yang}, year={2005} }
 @article{zhang_vijayaraghavan_seigneur_2005, title={Evaluation of three probing techniques in a three-dimensional air quality model}, volume={110}, number={D2}, journal={Journal of Geophysical Research. Atmospheres}, author={Zhang, Y. and Vijayaraghavan, K. and Seigneur, C.}, year={2005} }
 @article{zhang_bischof_easter_wu_2005, title={Sensitivity analysis of photochemical indicators for O-3 chemistry using automatic differentiation}, volume={51}, ISSN={["0167-7764"]}, DOI={10.1007/s10874-005-5440-8}, number={1}, journal={JOURNAL OF ATMOSPHERIC CHEMISTRY}, author={Zhang, Y and Bischof, CH and Easter, RC and Wu, PT}, year={2005}, month={May}, pages={1–41} }
 @article{zhang_pun_wu_vijayaraghavan_seigneur_2004, title={Application and evaluation of two Air Quality Models for particulate matter for a southeastern US episode}, volume={54}, ISSN={["2162-2906"]}, DOI={10.1080/10473289.2004.10471012}, abstractNote={Abstract The Models-3 Community Multiscale Air Quality (CMAQ) Modeling System and the Particulate Matter Comprehensive Air Quality Model with extensions (PMCAMx) were applied to simulate the period June 29–July 10, 1999, of the Southern Oxidants Study episode with two nested horizontal grid sizes: a coarse resolution of 32 km and a fine resolution of 8 km. The predicted spatial variations of ozone (O3), particulate matter with an aerodynamic diameter less than or equal to 2.5 μm (PM2.5), and particulate matter with an aerodynamic diameter less than or equal to 10 μm (PM10) by both models are similar in rural areas but differ from one another significantly over some urban/suburban areas in the eastern and southern United States, where PMCAMx tends to predict higher values of O3 and PM than CMAQ. Both models tend to predict O3 values that are higher than those observed. For observed O3 values above 60 ppb, O3 performance meets the U.S. Environmental Protection Agency's criteria for CMAQ with both grids and for PMCAMx with the fine grid only. It becomes unsatisfactory for PMCAMx and marginally satisfactory for CMAQ for observed O3 values above 40 ppb. Both models predict similar amounts of sulfate (SO4 2−) and organic matter, and both predict SO4 2− to be the largest contributor to PM2.5. PMCAMx generally predicts higher amounts of ammonium (NH4 +), nitrate (NO3 −), and black carbon (BC) than does CMAQ. PM performance for CMAQ is generally consistent with that of other PM models, whereas PMCAMx predicts higher concentrations of NO3 −,NH4 +, and BC than observed, which degrades its performance. For PM10 and PM2.5 predictions over the southeastern U.S. domain, the ranges of mean normalized gross errors (MNGEs) and mean normalized bias are 37–43% and –33–4% for CMAQ and 50–59% and 7–30% for PMCAMx. Both models predict the largest MNGEs for NO3 − (98–104% for CMAQ, 138–338% for PMCAMx). The inaccurate NO3 − predictions by both models may be caused by the inaccuracies in the ammonia emission inventory and the uncertainties in the gas/particle partitioning under some conditions. In addition to these uncertainties, the significant PM overpredictions by PMCAMx may be attributed to the lack of wet removal for PM and a likely underprediction in the vertical mixing during the daytime.}, number={12}, journal={JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION}, author={Zhang, Y and Pun, B and Wu, SY and Vijayaraghavan, K and Seigneur, C}, year={2004}, month={Dec}, pages={1478–1493} }
 @article{zhang_2004, title={Development and application of the Model of Aerosol Dynamics, Reaction, Ionization, and Dissolution (MADRID)}, volume={109}, ISSN={0148-0227}, url={http://dx.doi.org/10.1029/2003JD003501}, DOI={10.1029/2003JD003501}, abstractNote={A new aerosol model, the Model of Aerosol Dynamics, Reaction, Ionization, and Dissolution (MADRID) has been developed to simulate atmospheric particulate matter (PM). MADRID and the Carnegie‐Mellon University (CMU) bulk aqueous‐phase chemistry have been incorporated into the three‐dimensional Models‐3/Community Multiscale Air Quality model (CMAQ). The resulting model, CMAQ‐MADRID, is applied to simulate the August 1987 episode in the Los Angeles basin. Model performance for ozone and PM is consistent with current performance standards. However, organic aerosol was underpredicted at most sites owing to underestimation of primary organic PM emissions and secondary organic aerosol (SOA) formation. Nitrate concentrations were also sometimes underpredicted, mainly owing to overpredictions in vertical mixing, underpredictions in relative humidity, and uncertainties in the emissions of primary pollutants. Including heterogeneous reactions changed hourly O3 by up to 17% and 24‐hour average PM2.5, sulfate2.5, and nitrate2.5 concentrations by up to 3, 7, and 19%, respectively. A SOA module with a mechanistic representation provides results that are more consistent with observations than that with an empirical representation. The moving‐center scheme for particle growth predicts more accurate size distributions than a typical semi‐Lagrangian scheme, which causes an upstream numerical diffusion. A hybrid approach that simulates dynamic mass transfer for coarse PM but assumes equilibrium for fine PM can predict a realistic particle size distribution under most conditions, and the same applies under conditions with insignificant concentrations of reactive coarse particles to a bulk equilibrium approach that allocates transferred mass to different size sections based on condensational growth law. In contrast, a simple bulk equilibrium approach that allocates transferred mass based on a given distribution tends to cause a downstream numerical diffusion in the predicted particle size distribution.}, number={D1}, journal={Journal of Geophysical Research}, publisher={American Geophysical Union (AGU)}, author={Zhang, Yang}, year={2004} }
 @article{zhang_pun_vijayaraghavan_wu_seigneur_pandis_jacobson_nenes_seinfeld_2004, title={Development and application of the model of aerosol dynamics, reaction, ionization, and dissolution (MADRID)}, volume={109}, number={D1}, journal={Journal of Geophysical Research. Atmospheres}, author={Zhang, Y. and Pun, B. and Vijayaraghavan, K. and Wu, S. Y. and Seigneur, C. and Pandis, S. N. and Jacobson, M. Z. and Nenes, A. and Seinfeld, J. H.}, year={2004}, pages={D01202} }
 @misc{easter_ghan_zhang_saylor_chapman_laulainen_abdul-razzak_leung_bian_zaveri_2004, title={MIRAGE: Model description and evaluation of aerosols and trace gases}, volume={109}, ISSN={["2169-8996"]}, DOI={10.1029/2004jd004571}, abstractNote={The Model for Integrated Research on Atmospheric Global Exchanges (MIRAGE) modeling system, designed to study the impacts of anthropogenic aerosols on the global environment, is described. MIRAGE consists of a chemical transport model coupled online with a global climate model. The chemical transport model simulates trace gases, aerosol number, and aerosol chemical component mass (sulfate, methane sulfonic acid (MSA), organic matter, black carbon (BC), sea salt, and mineral dust) for four aerosol modes (Aitken, accumulation, coarse sea salt, and coarse mineral dust) using the modal aerosol dynamics approach. Cloud‐phase and interstitial aerosol are predicted separately. The climate model, based on Community Climate Model, Version 2 (CCM2), has physically based treatments of aerosol direct and indirect forcing. Stratiform cloud water and droplet number are simulated using a bulk microphysics parameterization that includes aerosol activation. Aerosol and trace gas species simulated by MIRAGE are presented and evaluated using surface and aircraft measurements. Surface‐level SO2 in North American and European source regions is higher than observed. SO2 above the boundary layer is in better agreement with observations, and surface‐level SO2 at marine locations is somewhat lower than observed. Comparison with other models suggests insufficient SO2 dry deposition; increasing the deposition velocity improves simulated SO2. Surface‐level sulfate in North American and European source regions is in good agreement with observations, although the seasonal cycle in Europe is stronger than observed. Surface‐level sulfate at high‐latitude and marine locations, and sulfate above the boundary layer, are higher than observed. This is attributed primarily to insufficient wet removal; increasing the wet removal improves simulated sulfate at remote locations and aloft. Because of the high sulfate bias, radiative forcing estimates for anthropogenic sulfur given in 2001 by S. J. Ghan and colleagues are probably too high. Surface‐level dimethyl sulfide (DMS) is ∼40% higher than observed, and the seasonal cycle shows too much DMS in local winter, partially caused by neglect of oxidation by NO3. Surface‐level MSA at marine locations is ∼80% higher than observed, also attributed to insufficient wet removal. Surface‐level BC is ∼50% lower than observed in the United States and ∼40% lower than observed globally. Treating BC as initially hydrophobic would lessen this bias. Surface‐level organic matter is lower than observed in the United States, similar to BC, but shows no bias in the global comparison. Surface‐level sea salt concentrations are ∼30% lower than observed, partly caused by low temporal variance of the model's 10 m wind speeds. Submicrometer sea salt is strongly underestimated by the emissions parameterization. Dust concentrations are within a factor of 3 at most sites but tend to be lower than observed, primarily because of neglect of very large particles and underestimation of emissions and vertical transport under high‐wind conditions. Accumulation and Aitken mode number concentrations and mean sizes at the surface over ocean, and condensation nuclei concentrations aloft over the Pacific, are in fair agreement with observations. Concentrations over land are generally higher than observations, with mean sizes correspondingly lower than observations, especially at some European locations. Increasing the assumed size of emitted particles produces better agreement at the surface over land, and reducing the particle nucleation rate improves the agreement aloft over land.}, number={D20}, journal={JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES}, author={Easter, RC and Ghan, SJ and Zhang, Y and Saylor, RD and Chapman, EG and Laulainen, NS and Abdul-Razzak, H and Leung, LR and Bian, XD and Zaveri, RA}, year={2004}, month={Oct} }
 @article{zhang_easter_ghan_abdul-razzak_2002, title={Impact of aerosol size representations on modeling aerosol-cloud interactions}, volume={107}, journal={Journal of Geophysical Research. Atmospheres}, author={Zhang, Y. and Easter, R. C. and Ghan, S. J. and Abdul-Razzak, H.}, year={2002}, pages={4558} }
 @article{ghan_easter_chapman_abdul-razzak_zhang_leung_laulainen_saylor_zaveri_2001, title={A physically based estimate of radiative forcing by anthropogenic sulfate aerosol}, volume={106}, ISSN={["0747-7309"]}, DOI={10.1029/2000JD900503}, abstractNote={Estimates of direct and indirect radiative forcing by anthropogenic sulfate aerosols from an integrated global aerosol and climate modeling system are presented. A detailed global tropospheric chemistry and aerosol model that predicts concentrations of oxidants as well as aerosols and aerosol precursors, is coupled to a general circulation model that predicts both cloud water mass and cloud droplet number. Both number and mass of several externally mixed aerosol size modes are predicted, with internal mixing assumed for the different aerosol components within each mode. Predicted aerosol species include sulfate, organic and black carbon, soil dust, and sea salt. The models use physically based treatments of aerosol radiative properties (including dependence on relative humidity) and aerosol activation as cloud condensation nuclei. Parallel simulations with and without anthropogenic sulfate aerosol are performed for a global domain. The global and annual mean direct and indirect radiative forcing due to anthropogenic sulfate are estimated to be −0.3 to −0.5 and −1.5 to −3.0 W m−2, respectively. The radiative forcing is sensitive to the model's horizontal resolution, the use of predicted versus analyzed relative humidity, the prediction versus diagnosis of aerosol number and droplet number, and the parameterization of droplet collision/coalescence. About half of the indirect radiative forcing is due to changes in droplet radius and half to increased cloud liquid water.}, number={D6}, journal={JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES}, author={Ghan, SJ and Easter, RC and Chapman, EG and Abdul-Razzak, H and Zhang, Y and Leung, LR and Laulainen, NS and Saylor, RD and Zaveri, RA}, year={2001}, month={Mar}, pages={5279–5293} }
 @article{ghan_laulainen_easter_wagener_nemesure_chapman_zhang_leung_2001, title={Evaluation of aerosol direct radiative forcing in MIRAGE}, volume={106}, ISSN={["0747-7309"]}, DOI={10.1029/2000JD900502}, abstractNote={A variety of measurements have been used to evaluate the treatment of aerosol radiative properties and radiative impacts of aerosols simulated by the Model for Integrated Research on Atmospheric Global Exchange (MIRAGE). The treatment of water uptake in MIRAGE agrees with laboratory measurements, and the growth of aerosol extinction with relative humidity in MIRAGE simulations agrees with field measurements. The simulated frequency of relative humidity near 100% is about twice that of analyzed relative humidity. When the analyzed relative humidity is used to calculate aerosol water uptake in MIRAGE, the simulated aerosol optical depth agrees with most surface measurements after cloudy conditions are filtered out and differences between model and station elevations are accounted for, but simulated optical depths are too low over Brazil and central Canada. Simulated optical depths are mostly within a factor of 2 of satellite estimates, but are too high off the east coasts of the United States and China and too low off the coast of West Africa and in the Arabian Sea. The simulated single‐scatter albedo is consistent with surface measurements. MIRAGE correctly simulates a larger Ångström exponent near regions with emissions of submicron particles and aerosol precursor gases, and a smaller exponent near regions with emissions of coarse particles. The simulated sensitivity of radiative forcing to aerosol optical depth is consistent with estimates from measurements. The simulated direct forcing is within the uncertainty of estimates from measurements in the North Atlantic.}, number={D6}, journal={JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES}, author={Ghan, S and Laulainen, N and Easter, R and Wagener, R and Nemesure, S and Chapman, E and Zhang, Y and Leung, R}, year={2001}, month={Mar}, pages={5295–5316} }
 @article{zhang_seigneur_seinfeld_jacobson_clegg_binkowski_2000, title={A comparative review of inorganic aerosol thermodynamic equilibrium modules: similarities, differences, and their likely causes}, volume={34}, ISSN={["1352-2310"]}, DOI={10.1016/S1352-2310(99)00236-8}, abstractNote={A comprehensive comparison of five inorganic aerosol thermodynamic equilibrium modules, MARS-A, SEQUILIB, SCAPE2, EQUISOLV II, and AIM2, was conducted for a variety of atmospheric concentrations of particulate matter (PM) constituents, relative humidities (RHs), and temperatures. Our results show that although the PM compositions and concentrations predicted by these modules are generally comparable under most conditions, significant discrepancies exist under some conditions, especially at high nitrate/chloride concentrations and low/medium RHs. As a consequence, the absolute differences in total PM concentrations predicted by these modules under all simulation conditions are 7.7–12.3% on average and as much as 68% for specific cases. The PM predictions are highly sensitive to changes in the molar ratios of ammonium to sulfate, nitrate to sulfate, and sodium chloride to sulfate, relative humidity, and temperature. The similarities and differences in simulation results predicted by the five modules are analyzed and the likely causes for these differences are discussed in detail. Recommendations are provided regarding the relative advantages of these modules, possible improvements of their performance, and applications in three-dimensional PM modeling studies.}, number={1}, journal={ATMOSPHERIC ENVIRONMENT}, author={Zhang, Y and Seigneur, C and Seinfeld, JH and Jacobson, M and Clegg, SL and Binkowski, FS}, year={2000}, pages={117–137} }
 @article{karamchandani_santos_sykes_zhang_tonne_seigneur_2000, title={Development and evaluation of a state-of-the-science reactive plume model}, volume={34}, ISSN={["1520-5851"]}, DOI={10.1021/es990611v}, abstractNote={The authors describe the development and evaluation of a new reactive plume model that combines a state-of-the-science puff model with an optimized chemistry model that accurately represents the chemistry of a power plant plume at various stages of its evolution. The puff model uses a second-order closure scheme, allowing for an accurate treatment of dispersion and the influence of turbulent concentration fluctuations on chemical rates. The model was tested using helicopter plume measurements from the 1995 Southern Oxidants Study (SOS) Nashville/Middle Tennessee Ozone Study. The model was applied for 6 days in June and July of 1995, and the model's ability to estimate physical and chemical plume characteristics, such as plume width and reactive species concentrations, was evaluated using the helicopter measurements. The best model results are for July 7, 1995, a case corresponding to a high NO{sub x} isolated power plant plume traveling over rural regions--model estimates of NO{sub x}, NO{sub y}, and O{sub 3} are highly correlated with measured values, and most of the measured plume centerline concentrations are reproduced to within 30%. For scenarios involving the interaction of the tracked plume with urban plumes or with other power plant plumes, model estimates of ozone concentrations are poorlymore » correlated with observations, emphasizing the difficulty of characterizing such plumes from both measurement and modeling perspectives.« less}, number={5}, journal={ENVIRONMENTAL SCIENCE & TECHNOLOGY}, author={Karamchandani, P and Santos, L and Sykes, I and Zhang, Y and Tonne, C and Seigneur, C}, year={2000}, month={Mar}, pages={870–880} }
 @inproceedings{zhang_easter_ghan_abdul-razzak_1999, title={Impact of aerosol size representations on aerosol modeling}, ISBN={1853126934}, booktitle={Air pollution VII}, publisher={Southampton: WIT}, author={Zhang, Y. and Easter, R. C. and Ghan, S. J. and Abdul-Razzak, H.}, editor={M. Jacobson, C. A. Brebbia and Power, H.Editors}, year={1999}, pages={979–988} }
 @article{zhang_seigneur_seinfeld_jacobson_binkowski_1999, title={Simulation of aerosol dynamics: A comparative review of algorithms used in air quality models}, volume={31}, ISSN={["0278-6826"]}, DOI={10.1080/027868299304039}, abstractNote={A comparative review of algorithms currently used in air quality models to simulate aerosol dynamics is presented. This review addresses coagula- tion, condensational growth, nucleation, and gas rparticle mass transfer. Two major approaches are used in air quality models to represent the particle size ( ) distribution: 1 the sectional approach in which the size distribution is discretized into sections and particle properties are assumed to be constant over particle size ( ) sections and 2 the modal approach in which the size distribution is approxi- mated by several modes and particle properties are assumed to be uniform in each mode. The sectional approach is accurate for coagulation and can reproduce the major characteristics of the evolution of the particle size distribution for condensa- tional growth with the moving-center and hybrid algorithms. For coagulation and condensational growth, the modal approach provides more accurate results when the standard deviations of the modes are allowed to vary than it does when they are ® xed. Predictions of H SO nucleation rates are highly sensitive to environ- 2 4 mental variables and simulation of relative rates of condensation on existing particles and nucleation is a preferable approach. Explicit treatment of mass transfer is recommended for cases where volatile species undergo different equilib- ( rium reactions in different particle size ranges e.g., in the presence of coarse salt ) particles . The results of this study provide useful information for use in selecting algorithms to simulate aerosol dynamics in air quality models and for improving the accuracy of existing algorithms.}, number={6}, journal={AEROSOL SCIENCE AND TECHNOLOGY}, author={Zhang, Y and Seigneur, C and Seinfeld, JH and Jacobson, MZ and Binkowski, FS}, year={1999}, month={Dec}, pages={487–514} }
 @article{zhang_carmichael_1999, title={The role of mineral aerosol in tropospheric chemistry in East Asia - A model study}, volume={38}, ISSN={["0894-8763"]}, DOI={10.1175/1520-0450(1999)038<0353:TROMAI>2.0.CO;2}, abstractNote={A detailed gas-phase chemistry mechanism is combined with dust surface uptake processes to explore possible impacts of mineral dust on tropospheric chemistry. The formations of sulfate and nitrate on dust are studied along with the dust effects on the photochemical oxidant cycle for the long-range-transported particles with a diameter of 0.1‐40 mm. The results show that mineral dust may influence tropospheric sulfate, nitrate, and O 3 formation by affecting trace gas concentrations and the tropospheric oxidation capacity through surface processes. The postulated heterogeneous mechanism provides a plausible interpretation for the observed high nitrate and sulfate on dust and the anticorrelation between O 3 and dust in East Asia. The presence of dust results in decreases in the concentrations of SO 2 (10%‐53%), (16%‐100%, defined as NO 3 1 N2O5 1 HNO3), HxOy (11%‐59%, p NOy defined as OH1 HO2 1 H2O2), and O3 (11%‐40%) under model conditions representative of spring dust storms in East Asia. The decrease in solar actinic flux and the surface uptake of O 3 and its precursors contribute to the total O 3 decrease for the conditions studied. Nitrate and sulfate, 0.9‐2.1 and 0.3‐10 m gm 23, respectively, are formed on dust particles, mostly in the size range of 1.5‐10 mm. The magnitude of the dust effect strongly depends on the preexisting dust surfaces, the initial conditions, and the selection of model parameters associated with surface uptake processes. The impact of dust reactions on O 3 reduction is highly sensitive to the uptake coefficient and to the possible renoxification from the surface reaction of HNO 3 on dust.}, number={3}, journal={JOURNAL OF APPLIED METEOROLOGY}, author={Zhang, Y and Carmichael, GR}, year={1999}, month={Mar}, pages={353–366} }
 @article{xiao_carmichael_zhang_1998, title={A modeling evaluation of the impact of mineral aerosol on the particulate sulfate formation in East Asia}, volume={22}, number={3}, journal={Chinese Journal of Atmospheric Sciences = Da Qi Ke Xue = Scientia Atmospherica Sinica}, author={Xiao, H. and Carmichael, G. R. and Zhang, Y.}, year={1998}, pages={343–353} }
 @article{xiao_carmichael_zhang_1998, title={Modeling studies for the effects of spring-time mineral aerosols on the transport and deposition of sulfur in East Asia using the STEM-II model}, volume={3}, number={2}, journal={Climatic and Environmental Research (Chinese)}, author={Xiao, H. and Carmichael, G. R. and Zhang, Y.}, year={1998}, pages={106–116} }
 @article{zhang_bischof_easter_wu_1998, title={Sensitivity analysis of a mixed-phase chemical mechanism using automatic differentiation}, volume={103}, ISSN={["2169-897X"]}, DOI={10.1029/98jd01278}, abstractNote={A sensitivity analysis of a comprehensive mixed‐phase chemical mechanism is conducted under a variety of atmospheric conditions. The local sensitivities of gas and aqueous phase species concentrations with respect to a variety of model parameters are calculated using the novel automatic differentiation ADIFOR tool. The main chemical reaction pathways in all phases, interfacial mass transfer processes, and ambient physical parameters that affect tropospheric O3 formation and O3‐precursor relations under all modeled conditions are identified and analyzed. The results show that the presence of clouds not only reduces many gas phase species concentrations and the total oxidizing capacity but alters O3‐precursor relations. Decreases in gas phase concentrations and photochemical formation rates of O3 can be up to 9% and 100%, respectively, depending on the preexisting atmospheric conditions. The decrease in O3 formation is primarily caused by the aqueous phase reactions of O2− with dissolved HO2 and O3 under most cloudy conditions.}, number={D15}, journal={JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES}, author={Zhang, Y and Bischof, CH and Easter, RC and Wu, PT}, year={1998}, month={Aug}, pages={18953–18979} }
 @article{carmichael_uno_phadnis_zhang_sunwoo_1998, title={Tropospheric ozone production and transport in the springtime in east Asia}, volume={103}, ISSN={["2169-8996"]}, DOI={10.1029/97JD03740}, abstractNote={Ozone transport and chemistry in the springtime in east Asia are studied by use of the STEM‐II (Sulfur Transport Eulerian Model) regional‐scale transport/chemistry model. Three‐dimensional simulations are performed for the period May 1–15, 1987. This was a period of strong downward transport of ozone in east Asia, associated with traveling low‐pressure systems. Elevated ozone levels were observed at high‐altitude surface sites in Japan during this period. Model simulations both with and without photochemical processes are performed in order to assess the relative importance of the transport and chemical sources of tropospheric ozone. The model results are compared with measured values at a network of stations in Japan and are found to accurately capture most of the important observed features. Near‐surface ozone levels are found to be strongly influenced both by continental outflow of precursors occurring behind the cold fronts as they move out over the Pacific Ocean and by the strong downward transport of ozone‐rich air from the upper troposphere which occurs in association with these weather systems.}, number={D9}, journal={JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES}, author={Carmichael, GR and Uno, I and Phadnis, MJ and Zhang, Y and Sunwoo, Y}, year={1998}, month={May}, pages={10649–10671} }
 @misc{dentener_carmichael_zhang_lelieveld_crutzen_1996, title={Role of mineral aerosol as a reactive surface in the global troposphere}, volume={101}, ISSN={["2169-8996"]}, DOI={10.1029/96JD01818}, abstractNote={A global three‐dimensional model of the troposphere is used to simulate the sources, abundances, and sinks of mineral aerosol and the species involved in the photochemical oxidant, nitrogen, and sulfur cycles. Although the calculated heterogeneous removal rates on mineral aerosol are highly uncertain, mainly due to poorly known heterogeneous reaction rates, the reaction of SO2 on calcium‐rich mineral aerosol is likely to play an important role downwind of arid source regions. This is especially important for regions in Asia, which are important and increasing emitters of sulfur compounds. Our results indicate that the assumption that sulfate aerosol follows an accumulation mode size distribution, is particularly in Asia likely to overestimate the sulfate aerosol climate‐cooling effect. An even larger fraction of gas phase nitric acid may be associated with and neutralized by mineral aerosol. Interactions of N2O5, O3, and HO2‐radicals with dust are calculated to affect the photochemical oxidant cycle, causing ozone decreases up to 10% in and nearby the dust source areas. Comparison of these results with limited available measurements indicates that the proposed reactions can indeed take place, although due to a lack of measurements a rigorous evaluation is not possible at this time.}, number={D17}, journal={JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES}, author={Dentener, FJ and Carmichael, GR and Zhang, Y and Lelieveld, J and Crutzen, PJ}, year={1996}, month={Oct}, pages={22869–22889} }
 @article{carmichael_zhang_chen_hong_ueda_1996, title={Seasonal variation of aerosol composition at Cheju Island, Korea}, volume={30}, ISSN={["1352-2310"]}, DOI={10.1016/1352-2310(95)00230-8}, abstractNote={A preliminary assessment of the seasonal variation in chemical composition of aerosols measured at Cheju Island, Korea, is presented. Weekly and monthly averaged aerosol composition derived from 15 months of daily filter measurements are presented. The annual-average non-sea-salt sulfate and nitrate mass concentrations of aerosols measured at Cheju are found to be 6.9 μg m−3 and 1.2 μg m−3, respectively; calcium and potassium are present in nearly equal quantities at ∼ 0.5 μgm-3, and ammonium averaged 1.4 μg m−3. Each species is found to follow a seasonal cycle with sulfate, nitrate, ammonium, potassium and calcium all showing up to 50% higher values in the spring. In contrast, chlorine is 30% lower in the spring. Aerosol enrichment factors relative to the composition of seawater and crustal material from the Gobi dust-source region in China are also presented. The aerosol measured at Cheju is found to be enriched in sulfate, nitrate and ammonium, but deficient in chlorine (relative to seawater). These results along with modeling studies suggest that the dust surfaces play an important role in nitrate and sulfate formation.}, number={13}, journal={ATMOSPHERIC ENVIRONMENT}, author={Carmichael, GR and Zhang, Y and Chen, LL and Hong, MS and Ueda, H}, year={1996}, month={Jul}, pages={2407–2416} }
 @inproceedings{zhang_chen_carmichael_dentener_1996, title={The role of mineral aerosols in tropospheric chemistry}, ISBN={0306453819}, DOI={10.1007/978-1-4615-5841-5_26}, booktitle={Air pollution modeling and its application XI}, publisher={New York: Plenum Press}, author={Zhang, Y. and Chen, L.-L. and Carmichael, G. R. and Dentener, F.}, editor={Gryning, S.-E. and Schiermeier, F. A.Editors}, year={1996}, pages={239–248} }
 @inproceedings{arndt_xu_carmichael_sunwoo_zhang_1994, title={Long range transport of SO x in Asia}, ISBN={1853123609}, booktitle={Air pollution II}, publisher={Southampton; Boston: Computational Mechanics Publications}, author={Arndt, R. and Xu, Y. and Carmichael, G. R. and Sunwoo, Y. and Zhang, Y.}, editor={al., J. M. BaldasanoEditor}, year={1994}, pages={245–250} }
 @article{zhang_young_kotamarthi_carmichael_1994, title={PHOTOCHEMICAL OXIDANT PROCESSES IN THE PRESENCE OF DUST - AN EVALUATION OF THE IMPACT OF DUST ON PARTICULATE NITRATE AND OZONE FORMATION}, volume={33}, ISSN={["0894-8763"]}, DOI={10.1175/1520-0450(1994)033<0813:POPITP>2.0.CO;2}, abstractNote={Abstract The influence of dust on the tropospheric photochemical oxidant cycle is studied through the use of a detailed coupled aerosol and gas-phase chemistry model. Dust is a significant component of the troposphere throughout Asia and provides a surface for a variety of heterogeneous reactions. Dust is found to be an important surface for particulate nitrate formation. For dust loading and ambient concentrations representative of conditions in East Asia, particulate nitrate levels of 1.5–11.5 µg m−3 are predicted, consistent with measured levels in this region. Dust is also found to reduce NOx levels by up to 50%, HO2 concentrations by 20%–80%, and ozone production rates by up to 25%. The magnitude of the influence of dust is sensitive to the mass concentration of the aerosol, relative humility, and the value of the accommodation coefficient.}, number={7}, journal={JOURNAL OF APPLIED METEOROLOGY}, author={ZHANG, Y and YOUNG, SW and KOTAMARTHI, V and CARMICHAEL, GR}, year={1994}, month={Jul}, pages={813–824} }
 @inproceedings{zhang_sunwoo_carmichael_1993, title={Effects of yellow sand on the photochemical processes in East Asia}, ISBN={7800032825}, booktitle={Emerging technologies for environment protection: Preparing for the 21st century: Proceedings of World Congress III on Engineering and Environment, October 12-14, 1993, Beijing, China}, publisher={Beijing: International Academic Publishers}, author={Zhang, Y. and Sunwoo, Y. and Carmichael, G. R.}, editor={Y. Qian, J.-M. Hao and Long, J.Editors}, year={1993}, pages={697–704} }
 @inproceedings{carmichael_sunwoo_zhang_1993, title={Long range transport of air pollutants in Asia}, ISBN={185312222X}, booktitle={Air pollution}, publisher={Southampton; Boston: Computational Mechanics Publications; London: Elsevier Science}, author={Carmichael, G. R. and Sunwoo, Y. and Zhang, Y.}, editor={al., P. ZannettiEditor}, year={1993}, pages={281–292} }
 @inproceedings{zhang_sunwoo_kotamarthi_carmichael_1993, title={Photochemical oxidant processes in the presence of dust: An evaluation of the impact of dust on sulfate, nitrate and ozone formation}, booktitle={Conference on Atmospheric Chemistry, January 17-22, 1993, Anaheim, California}, publisher={Boston, Mass: American Meteorological Society}, author={Zhang, Y. and Sunwoo, Y. and Kotamarthi, V. and Carmichael, G. R.}, year={1993}, pages={9–10} }
 @article{hao_li_zhang_1990, title={Chance-constrained programming (CCP) abatement of SO2 emission for acid deposition control in Liuzhou}, volume={2}, number={3}, journal={Journal of Environmental Sciences (China)}, author={Hao, J.-M. and Li, G. and Zhang, Y.}, year={1990}, pages={35–49} }
 @inproceedings{chen_wang_zhang_1990, title={Characteristics of atmospheric pollutants and their sources in Beijing area}, booktitle={Global and regional environmental atmospheric chemistry: Proceedings of the International Conference on Global and Regional Environmental Chemistry, Beijing, China, May 3-10, 1989}, publisher={Washington, DC: U.S. Dept. of Energy}, author={Chen, Z.-L. and Wang, Y.-B. and Zhang, Y.}, editor={L. Newman, W.-X. Wang and Kiang, C. S.Editors}, year={1990}, pages={640–641} }
 @article{chen_zhang_1990, title={Estimate of the conversion rates of SO2 to SO4 2- and NO2 to HNO3+NO3 - for the evaluation of air pollution in Beijing}, volume={2}, number={1}, journal={Journal of Environmental Sciences (China)}, author={Chen, Z.-L and Zhang, Y.}, year={1990}, pages={41–48} }
 @article{zhang_ma_1987, title={A dynamic model of thermodynamic NOx formation in the combustion processes and its application}, volume={1}, number={2}, journal={Youth Environmental Scientists (China)}, author={Zhang, Y. and Ma, Y.-L.}, year={1987}, pages={38–42} }