@misc{yu_2014, title={Water spray geoengineering to clean air pollution for mitigating haze in China's cities}, volume={12}, ISSN={["1610-3661"]}, DOI={10.1007/s10311-013-0444-0}, number={1}, journal={ENVIRONMENTAL CHEMISTRY LETTERS}, author={Yu, Shaocai}, year={2014}, month={Mar}, pages={109–116} }
 @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{tong_mathur_kang_yu_schere_pouliot_2009, title={Vegetation exposure to ozone over the continental United States: Assessment of exposure indices by the Eta-CMAQ air quality forecast model}, volume={43}, ISSN={["1873-2844"]}, DOI={10.1016/j.atmosenv.2008.09.084}, abstractNote={The main use of air quality forecast (AQF) models is to predict ozone (O3) exceedances of the primary O3 standard for informing the public of potential health concerns. This study presents the first evaluation of the performance of the Eta-CMAQ air quality forecast model to predict a variety of widely used seasonal mean and cumulative O3 exposure indices associated with vegetation using the U.S. AIRNow O3 observations. These exposure indices include two concentration-based O3 indices, M7 and M12 (the seasonal means of daytime 7-h and 12-h O3 concentrations, respectively), and three cumulative exposure-based indices, SUM06 (the sum of all hourly O3 concentrations ≥ 0.06 ppm), W126 (hourly concentrations weighed by a sigmoidal weighting function), and AOT40 (O3 concentrations accumulated over a threshold of 40 ppb during daylight hours). During a three-month simulation (July–September 2005), the model over predicted the M7 and M12 values by 8–9 ppb, or a NMB value of 19% and a NME value of 21%. The model predicts a central belt of high O3 extending from Southern California to Middle Atlantic where the seasonal means, M7 and M12 (the seasonal means of daytime 7-h and 12-h O3 concentrations), are higher than 50 ppbv. In contrast, the model is less capable of reproducing the observed cumulative indices. For AOT40, SUM06 and W126, the NMB and NME values are two- to three-fold of that for M7, M12 or peak 8-h O3 concentrations. The AOT40 values range from 2 to 33 ppm h by the model and from 1 to 40 ppm h by the monitors. There is a significantly higher AOT40 value experienced in the United States in comparison to Europe. The domain-wide mean SUM06 value is 14.4 ppm h, which is about 30% higher than W126, and 40% higher than AOT40 calculated from the same 3-month hourly O3 data. This suggests that SUM06 and W126 represent a more stringent standard than AOT40 if either the SUM06 or the W126 was used as a secondary O3 standard. Although CMAQ considerably over predicts SUM06 and W126 values at the low end, the model under predicts the extreme high exposure values (>50 ppm h). Most of these extreme high values are found at inland California sites. Based on our analysis, further improvement of the model is needed to better capture cumulative exposure indices.}, number={3}, journal={ATMOSPHERIC ENVIRONMENT}, author={Tong, Daniel Q. and Mathur, Rohit and Kang, Daiwen and Yu, Shaocai and Schere, Kenneth L. and Pouliot, George}, year={2009}, month={Jan}, pages={724–733} }
 @article{yu_dennis_roselle_nenes_walker_eder_schere_swall_robarge_2005, title={An assessment of the ability of three-dimensional air quality models with current thermodynamic equilibrium models to predict aerosol NO3-}, volume={110}, ISSN={["2169-8996"]}, DOI={10.1029/2004jd004718}, abstractNote={The partitioning of total nitrate (TNO3) and total ammonium (TNH4) between gas and aerosol phases is studied with two thermodynamic equilibrium models, ISORROPIA and the aerosol inorganics model (AIM), and three data sets: high time resolution measurement data from the 1999 Atlanta Supersite Experiment (summer case) and the 2002 Pittsburgh Air Quality Study (PAQS) Supersite Experiment (winter case), and 12‐hour measurement data from the Clinton site, North Carolina, in 1999. At the Atlanta site, both models reproduced a large percentage of the observed aerosol NH4+ and HNO3 (NH4+: >94% and HNO3: >86%) within a factor of 1.5, whereas neither model reproduced a majority of observed aerosol NO3− and NH3 (NO3−: <48% and NH3: <51%) within a factor of 2. At the Pittsburgh site, both models reproduced more than 76% of observed NO3− within a factor of 2. At the Clinton site, both models performed a little better on aerosol NO3− (47–58% within a factor of 1.5) than at the Atlanta site but worse than at the Pittsburgh site. Sensitivity test of thermodynamic models with Gaussian random errors indicates that in many cases, measurement errors in SO42− and TNH4 can explain a major fraction of the discrepancies between the equilibrium model predictions and observations in partitioning of TNO3. Comparison of predictions of the three‐dimensional (3‐D) Community Multiscale Air Quality (CMAQ) model with the observations over the continental United States indicates that the performance of the 3‐D model for NO3−, HNO3, NH4+, and NH3 strongly depends on its performance for TNO3, TNH4, and SO42−. Tests show that errors associated with SO42− and TNH4 predictions of the 3‐D model can result in the thermodynamic model calculation replicating only 47% and 60% of base case NO3− within a factor of 2 for summer and winter cases, respectively. It was found that errors in TNH4 are more critical than errors in SO42− to prediction of NO3−.}, number={D7}, journal={JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES}, author={Yu, SC and Dennis, R and Roselle, S and Nenes, A and Walker, J and Eder, B and Schere, K and Swall, J and Robarge, W}, year={2005}, month={Feb} }
 @article{wright_yu_kasibhatla_mcgraw_schwartz_saxena_yue_2002, title={Retrieval of aerosol properties from moments of the particle size distribution for kernels involving the step function: cloud droplet activation}, volume={33}, ISSN={["0021-8502"]}, DOI={10.1016/S0021-8502(01)00172-0}, abstractNote={Aerosol properties such as the number of particles that activate to form cloud drops and the mass contained within specified size ranges (as in the PM 2.5 and PM 10 regulatory standards) require integration over only part of the full size range of the particle distribution function (PDF) and may be formally expressed as integrals over kernels involving the Heaviside step function. Determination of these properties requires essentially that the size spectrum be partitioned into two (or more) portions, and poses a special challenge for aerosol modeling with the method of moments. To assess the ability of moment-based methods to treat kernels involving step functions, several algorithms for the estimation of aerosol properties associated with cloud activation have been evaluated. For 240 measured continental distributions employed here as test cases, the full size spectrum of the PDF was partitioned into three distinct portions based upon characteristic critical radii for activation in cumulus and stratiform clouds, and mass- and number-concentration metrics were evaluated for each portion. The first six radial moments yielded results accurate to within about 10% or better, on average, and the numbers of particles activated as cloud drops and the aerosol mass taken into cloud water were estimated to an accuracy of 5% or better. Of the moment-based approaches evaluated, the multiple isomomental distribution aerosol surrogate (MIDAS) (Wright, J. Aerosol Sci. 31 (2000) 1) technique performed best. Accurate results were also obtained with the randomized minimization search technique (RMST) (Yue et al., Geophys. Res. Lett. 24 (1997) 651; Heintzenberg et al., Appl. Opt. 20 (1981) 1308).}, number={2}, journal={JOURNAL OF AEROSOL SCIENCE}, author={Wright, DL and Yu, SC and Kasibhatla, PS and McGraw, R and Schwartz, SE and Saxena, VK and Yue, GK}, year={2002}, month={Feb}, pages={319–337} }
 @article{yu_saxena_zhao_2001, title={A comparison of signals of regional aerosol-induced forcing in eastern China and the southeastern United States}, volume={28}, ISSN={["0094-8276"]}, DOI={10.1029/2000GL011834}, abstractNote={This paper compares the temperature change patterns and the signals of regional aerosol‐induced forcing in eastern China and the southeastern US during the latter half of the twentieth century. Both regions show decreasing trends in the mean maximum temperature over recent decades and the cooling effect of Pinatubo volcanic aerosols. In contrast to the southeastern US, we found a slight overall warming trend in eastern China. Our analysis suggests that in addition to greenhouse warming effect, observed high concentrations of absorbing aerosols over eastern China during winter and spring might be one of the major reasons for the observed warming trend.}, number={4}, journal={GEOPHYSICAL RESEARCH LETTERS}, author={Yu, SC and Saxena, VK and Zhao, ZC}, year={2001}, month={Feb}, pages={713–716} }
 @article{yu_zender_saxena_2001, title={Direct radiative forcing and atmospheric absorption by boundary layer aerosols in the southeastern US: model estimates on the basis of new observations}, volume={35}, ISSN={["1352-2310"]}, DOI={10.1016/S1352-2310(01)00187-X}, abstractNote={In an effort to reduce uncertainties in the quantification of aerosol direct radiative forcing (ADRF) in the southeastern United States (US), a field column experiment was conducted to measure aerosol radiative properties and effects at Mt. Mitchell, North Carolina, and at an adjacent valley site. The experimental period was from June 1995 to mid-December 1995. The aerosol optical properties (single scattering albedo and asymmetry factor) needed to compute ADRF were obtained on the basis of a procedure involving a Mie code and a radiative transfer code in conjunction with the retrieved aerosol size distribution, aerosol optical depth, and diffuse-to-direct solar irradiance ratio. The regional values of ADRF at the surface and top of atmosphere (TOA), and atmospheric aerosol absorption are derived using the obtained aerosol optical properties as inputs to the column radiation model (CRM) of the community climate model (CCM3). The cloud-free instantaneous TOA ADRFs for highly polluted (HP), marine (M) and continental (C) air masses range from 20.3 to −24.8, 1.3 to −10.4, and 1.9 to −13.4 W m−2, respectively. The mean cloud-free 24-h ADRFs at the TOA (at the surface) for HP, M, and C air masses are estimated to be −8±4 (−33±16), −7±4 (−13±8), and −0.14±0.05 (−8±3) W m−2, respectively. On the assumption that the fractional coverage of clouds is 0.61, the annual mean ADRFs at the TOA and the surface are −2±1, and −7±2 W m−2, respectively. This also implies that aerosols currently heat the atmosphere over the southeastern US by 5±3 W m−2 on annual timescales due to the aerosol absorption in the troposphere.}, number={23}, journal={ATMOSPHERIC ENVIRONMENT}, author={Yu, SC and Zender, CS and Saxena, VK}, year={2001}, month={Aug}, pages={3967–3977} }
 @article{yu_gao_cheng_cheng_cheng_xiao_we_1998, title={An analysis of chemical composition of different rain types in 'Minnan Golden Triangle' region in the southeastern coast of China}, volume={48}, DOI={10.1016/s0169-8095(98)00047-7}, abstractNote={The pollutants from anthropogenic activities can affect precipitation composition and subsequently affect aquatic and terrestrial ecosystems. Here, we reported the results from the simultaneous collection and chemical analysis (including F−, Cl−, NO3−, SO42−, HCOO−, CH3COO−, Na+, NH4+, K+, Ca2+, Mg2+, pH) of spring rain, mold rain and typhoon rain during 1990 and 1991 in the region of Xiamen, Quanzhou, Zhangzhou and Tongan, which is called `Minnan Golden Triangle' and is a rapidly growing urban area in the southeastern Coast of China. It was found that the average pHs of spring rain, mold rain and typhoon rain in 1990 in this region were 4.51, 4.93 and 5.14, respectively. Obviously, the spring rain was the most acidic in the three types of rains in this region. The average concentrations of formic and acetic acids in Xiamen mold rain were 5.67 and 2.91 μeq/l, respectively, and the average maximum contribution of organic acids to free acidity was in the range of 2.8% to 100% (average 66.3%). The regression equations between acidity and ions showed that SO42, NO3−, NH4+ and organic acids (formic and acetic) made the major contribution to the precipitation acidity in this region. The chemical characteristics of different precipitation types in this region indicated that spring rain had the character of continental origin, but the mold rain and typhoon rain had more effects from ocean. Since spring rain, mold rain, and typhoon rain were caused by precipitation cloud approaching to this region from different directions and had different acidity, and the average pH of cloud rainwater on the mountain site was 4.90, it is suggested that acid rain in this region might be mainly caused by long-range transport of pollutants from the southern Chinese mainland, and the local pollution sources were less as significant.}, number={Spec. Iss.}, journal={Atmospheric Research}, author={Yu, S. C. and Gao, C. T. and Cheng, Z. M. and Cheng, X. J. and Cheng, S. T. and Xiao, J. A. and We, W. X.}, year={1998}, pages={245–269} }
 @article{saxena_yu_1998, title={Searching for a regional fingerprint of aerosol radiative forcing in the southeastern US}, volume={25}, ISSN={["0094-8276"]}, DOI={10.1029/98GL02106}, abstractNote={Although aerosols have long been considered to exert a cooling influence on the regional climate due to direct and indirect radiative forcing, persuasive evidence of the response to this forcing has been lacking. Here, we analyze the regional patterns of climate change in the Southeast US during the period 1949–94 to search for a fingerprint of aerosol radiative forcing. The results show that direct and indirect radiative forcing of both natural (such as Pinatubo volcanic aerosols) and anthropogenic aerosols (such as those transported from the polluted regions of US) may be responsible for the regional cooling trend in the Southeast during the past 46 years. Lack of availability of long term measurements precludes a rigorous cause‐and‐effect analysis. Circumstantial evidence presented here amply justifies immediate establishment of a network of measurements of aerosol optical depth and cloud reflectivity in the southeastern US.}, number={15}, journal={GEOPHYSICAL RESEARCH LETTERS}, author={Saxena, VK and Yu, SC}, year={1998}, month={Aug}, pages={2833–2836} }
 @article{saxena_yu_anderson_1997, title={Impact of stratospheric volcanic aerosols on climate: Evidence for aerosol shortwave and longwave forcing in the southeastern US}, volume={31}, ISSN={["1352-2310"]}, DOI={10.1016/S1352-2310(97)00244-6}, abstractNote={Major volcanic eruptions inject massive amounts of dust and gases into the lower stratosphere and upper troposphere. Stratospheric volcanic aerosols can scatter incoming solar radiation to space, increasing planetary albedo, reducing the total amount of solar energy reaching the troposphere and the earth's surface, and decreasing the daytime maximum temperature (aerosol shortwave forcing). They can also absorb and scatter outgoing terrestrial longwave radiation, increasing the nighttime minimum surface temperature (longwave forcing). However, persuasive evidence of climate response to this forcing has thus far been lacking. Here we examine patterns of annual and seasonal variations in mean maximum and minimum temperature trend during the periods 1992–1994 and 1985–1987 relative to that during the period 1988–1990 at 47 stations in the southeastern U.S. for evidence of such climate responses. The stratospheric volcanic aerosol optical depths over the southeastern U.S. during the period 1985–1994 were inferred from the Stratospheric Aerosol and Gases Experiment (SAGE) 11 satellite extinction measurement. After the long-term trend signals are removed, it is shown that the dominant decreasing trend of mean maximum temperature and the dominant increasing trend of mean minimum temperature over periods 1992–1994 and 1985–1987 relative to that over the period 1988–1990 are consistent with the distribution of stratospheric volcanic aerosols and predictions from aerosol radiative forcing in the southeastern U.S.}, number={24}, journal={ATMOSPHERIC ENVIRONMENT}, author={Saxena, VK and Yu, SC and Anderson, J}, year={1997}, month={Dec}, pages={4211–4221} }
 @article{defelice_saxena_yu_1997, title={On the measurements of cloud condensation nuclei at Palmer Station, Antarctica}, volume={31}, ISSN={["1352-2310"]}, DOI={10.1016/S1352-2310(97)00250-1}, abstractNote={This article presents and discusses the predominant characteristics associated with a first dataset of daily daylight period (i.e. ≃13-15 h long) averaged cloud condensation nuclei spectral measurements at a remote region of the globe, namely Palmer Station, Antartica.}, number={23}, journal={ATMOSPHERIC ENVIRONMENT}, author={Defelice, TP and Saxena, VK and Yu, SC}, year={1997}, month={Dec}, pages={4039–4044} }