@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={Coupled air quality and climate models can predict aerosol concentrations and properties, as well as aerosol direct and indirect effects that depend on aerosol chemistry and microphysics treatments. In this study, Weather Research and Forecasting with Chemistry (WRF/Chem) simulations are conducted over continental U.S. (CONUS) for January and July 2001 with the same gas‐phase mechanism (CB05) but three aerosol modules (Modal Aerosol Dynamics Model for Europe/Secondary Organic Aerosol Model (MADE/SORGAM), Model for Simulating Aerosol Interactions and Chemistry (MOSAIC), and Model of Aerosol Dynamics, Reaction, Ionization and Dissolution (MADRID)) to examine the impacts of aerosol treatments on predictions of aerosols and their effects on cloud properties and radiation. The simulations with the three aerosol modules give similar domain mean predictions of surface PM2.5 concentrations but exhibit a strong spatial variation in magnitudes with large differences in eastern U.S. Large discrepancies are found in the predicted concentrations of sulfate and organic matter due to different treatments in secondary inorganic and secondary organic aerosol (SOA) formation. In particular, the nucleation calculation in MADE/SORGAM causes mass buildup of sulfate which results in much higher sulfate concentrations that those predicted by WRF/Chem with the other two aerosol modules. Different PM mass concentrations and size representations lead to differences in the predicted aerosol number concentrations. The above differences in PM concentrations lead to large differences in simulated condensation nuclei (CCN) and cloud properties in both months. The simulated ranges of domain mean are (1.9–14.3) × 109 m−3 and (1.4–5.4) × 109 m−3 for PM2.5 number concentration, (1.6–3.9) × 108 cm−2 and (1.9–3.9) × 108 cm−2 for CCN, 102.9–208.2 cm−3 and 143.7–202.2 cm−3 for column cloud droplet number concentration (CDNC), and 4.5–6.4 and 3.6–6.7 for cloud optical depths (COT) in January and July, respectively. The sensitivity simulation for July 2001 using online biogenic emissions increases isoprene concentrations but decreases terpene concentrations, leading to a domain mean increase in O3 (1.5 ppb) and a decrease in biogenic SOA (−0.07 µg m−3) and PM2.5 (−0.2 µg m−3). Anthropogenic emissions contribute to O3, biogenic SOA (BSOA), and PM2.5 concentrations by 38.0%, 44.2%, and 53.6% domain mean and by up to 78.5%, 89.7%, and 96.3%, respectively, indicating that a large fraction of BSOA is controllable through controlling atmospheric oxidant levels in CONUS. Anthropogenic emissions also contribute to a decrease in downward shortwave flux at ground surface (−5.8 W m−2), temperature at 2 m (−0.05°C), wind speed at 10 m (−0.02 m s−1), planetary boundary layer height (−6.6 m), and precipitation (−0.08 mm), as well as an increase in CCN (+5.7 × 10−7 cm−2), in‐cloud CDNC (+40.4 cm−3), and COT (+0.6). This work indicates the need for an accurate representation of several aerosol processes such as SOA formation and aerosol‐cloud interactions in simulating aerosol direct and indirect effects in the online‐coupled models.}, 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{gantt_johnson_crippa_prevot_meskhidze_2015, title={Implementing marine organic aerosols into the GEOS-Chem model}, volume={8}, number={3}, journal={Geoscientific Model Development}, author={Gantt, B. and Johnson, M. S. and Crippa, M. and Prevot, A. S. H. and Meskhidze, N.}, year={2015}, pages={619–629} }
 @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{meskhidze_petters_tsigaridis_bates_o'dowd_reid_lewis_gantt_anguelova_bhave_et al._2013, title={Production mechanisms, number concentration, size distribution, chemical composition, and optical properties of sea spray aerosols}, volume={14}, number={4}, journal={Atmospheric Science Letters}, author={Meskhidze, N. and Petters, M. D. and Tsigaridis, K. and Bates, T. and O'Dowd, C. and Reid, J. and Lewis, E. R. and Gantt, B. and Anguelova, M. D. and Bhave, P. V. and et al.}, year={2013}, pages={207–213} }
 @misc{gantt_meskhidze_2013, title={The physical and chemical characteristics of marine primary organic aerosol: a review}, volume={13}, ISSN={["1680-7324"]}, DOI={10.5194/acp-13-3979-2013}, abstractNote={Abstract. Knowledge of the physical characteristics and chemical composition of marine organic aerosols is needed for the quantification of their effects on solar radiation transfer and cloud processes. This review examines research pertinent to the chemical composition, size distribution, mixing state, emission mechanism, photochemical oxidation and climatic impact of marine primary organic aerosol (POA) associated with sea-spray. Numerous measurements have shown that both the ambient mass concentration of marine POA and size-resolved organic mass fraction of sea-spray aerosol are related to surface ocean biological activity. Recent studies have also indicated that fine mode (smaller than 200 nm in diameter) marine POA can have a size distribution independent from sea-salt, while coarse mode aerosols (larger than 1000 nm in diameter) are more likely to be internally mixed with sea-salt. Modelling studies have estimated global submicron marine POA emission rates of ~10 ± 5 Tg yr −1 , with a considerable fraction of these emissions occurring over regions most susceptible to aerosol perturbations. Climate studies have found that marine POA can cause large local increases in the cloud condensation nuclei concentration and have a non-negligible influence on model assessments of the anthropogenic aerosol forcing of climate. Despite these signs of climate-relevance, the source strength, chemical composition, mixing state, hygroscopicity, cloud droplet activation potential, atmospheric aging and removal of marine POA remain poorly quantified. Additional laboratory, field, and modelling studies focused on the chemistry, size distribution and mixing state of marine POA are needed to better understand and quantify their importance.}, number={8}, journal={ATMOSPHERIC CHEMISTRY AND PHYSICS}, author={Gantt, B. and Meskhidze, N.}, year={2013}, pages={3979–3996} }
 @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{gantt_johnson_meskhidze_sciare_ovadnevaite_ceburnis_o'dowd_2012, title={Model evaluation of marine primary organic aerosol emission schemes}, volume={12}, ISSN={["1680-7316"]}, DOI={10.5194/acp-12-8553-2012}, abstractNote={Abstract. In this study, several marine primary organic aerosol (POA) emission schemes have been evaluated using the GEOS-Chem chemical transport model in order to provide guidance for their implementation in air quality and climate models. These emission schemes, based on varying dependencies of chlorophyll a concentration ([chl a ]) and 10 m wind speed ( U 10 ), have large differences in their magnitude, spatial distribution, and seasonality. Model comparison with weekly and monthly mean values of the organic aerosol mass concentration at two coastal sites shows that the source function exclusively related to [chl a ] does a better job replicating surface observations. Sensitivity simulations in which the negative U 10 and positive [chl a ] dependence of the organic mass fraction of sea spray aerosol are enhanced show improved prediction of the seasonality of the marine POA concentrations. A top-down estimate of submicron marine POA emissions based on the parameterization that compares best to the observed weekly and monthly mean values of marine organic aerosol surface concentrations has a global average emission rate of 6.3 Tg yr −1 . Evaluation of existing marine POA source functions against a case study during which marine POA contributed the major fraction of submicron aerosol mass shows that none of the existing parameterizations are able to reproduce the hourly-averaged observations. Our calculations suggest that in order to capture episodic events and short-term variability in submicron marine POA concentration over the ocean, new source functions need to be developed that are grounded in the physical processes unique to the organic fraction of sea spray aerosol.}, number={18}, journal={ATMOSPHERIC CHEMISTRY AND PHYSICS}, author={Gantt, B. and Johnson, M. S. and Meskhidze, N. and Sciare, J. and Ovadnevaite, J. and Ceburnis, D. and O'Dowd, C. D.}, year={2012}, pages={8553–8566} }
 @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{gantt_meskhidze_facchini_rinaldi_ceburnis_o'dowd_2011, title={Wind speed dependent size-resolved parameterization for the organic mass fraction of sea spray aerosol}, volume={11}, ISSN={["1680-7324"]}, DOI={10.5194/acp-11-8777-2011}, abstractNote={For oceans to be a significant source of primary organic aerosol (POA), sea spray aerosol (SSA) must be highly enriched with organics relative to the bulk seawater. We propose that organic enrichment at the air-sea interface, chemical composition of seawater, and the aerosol size are three main parameters controlling the organic mass fraction of sea spray aerosol (OM SSA ). To test this hypothesis, we developed a new marine POA emission function based on a conceptual relationship between the organic enrichment at the air-sea interface and surface wind speed. The resulting parameterization is explored using aerosol chemical composition and surface wind speed from Atlantic and Pacific coastal stations, and satellite-derived ocean concentrations of chlorophyll- a , dissolved organic carbon, and particulate organic carbon. Of all the parameters examined, a multi-variable logistic regression revealed that the combination of 10 m wind speed and surface chlorophyll- a concentration ([Chl- a ]) are the most consistent predictors of OM SSA . This relationship, combined with the published aerosol size dependence of OM SSA , resulted in a new parameterization for the organic mass fraction of SSA. Global emissions of marine POA are investigated here by applying this newly-developed relationship to existing sea spray emission functions, satellite-derived [Chl- a ], and modeled 10 m winds. Analysis of model simulations shows that global annual submicron marine organic emission associated with sea spray is estimated to be from 2.8 to 5.6 Tg C yr −1 . This study provides additional evidence that marine primary organic aerosols are a globally significant source of organics in the atmosphere.}, number={16}, journal={ATMOSPHERIC CHEMISTRY AND PHYSICS}, author={Gantt, B. and Meskhidze, N. and Facchini, M. C. and Rinaldi, M. and Ceburnis, D. and O'Dowd, C. D.}, year={2011}, pages={8777–8790} }
 @article{gantt_meskhidze_carlton_2010, title={The contribution of marine organics to the air quality of the western United States}, volume={10}, ISSN={["1680-7324"]}, DOI={10.5194/acp-10-7415-2010}, abstractNote={Abstract. The contribution of marine organic emissions to the air quality in coastal areas of the western United States is studied using the latest version of the US Environmental Protection Agency (EPA) regional-scale Community Multiscale Air Quality (CMAQv4.7) modeling system. Emissions of marine isoprene, monoterpenes, and primary organic matter (POM) from the ocean are implemented into the model to provide a comprehensive view of the connection between ocean biology and atmospheric chemistry and air pollution. Model simulations show that marine organics can increase the concentration of PM2.5 by 0.1–0.3 μg m−3 (up to 5%) in some coastal cities such as San Francisco, CA. This increase in the PM2.5 concentration is primarily attributed to the POM emissions, with small contributions from the marine isoprene and monoterpenes. When marine organic emissions are included, organic carbon (OC) concentrations over the remote ocean are increased by up to 50% (25% in coastal areas), values consistent with recent observational findings. This study is the first to quantify the air quality impacts from marine POM and monoterpenes for the United States, and it highlights the need for inclusion of marine organic emissions in air quality models.}, number={15}, journal={ATMOSPHERIC CHEMISTRY AND PHYSICS}, author={Gantt, B. and Meskhidze, N. and Carlton, A. G.}, year={2010}, pages={7415–7423} }
 @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} }