2B.3 Impact of Updated Wet Scavenging Processes in GEOS-Chem on Global Simulation of Nitric Acid and Aerosols: Comparisons with U.S., European, and East Asian Surface and ATom Aircraft Measurements

Monday, 13 January 2020: 11:00 AM
206B (Boston Convention and Exhibition Center)
Gan Luo, Univ. at Albany, SUNY, Albany, NY; and F. Yu

Wet scavenging is one of the most important sinks of atmospheric aerosols and their precursors, impacting significantly global mass loading of these species. Recently we found that the considering of in-cloud condensation water variability (ICCWV) and empirical wash rates (EWR) in GEOS-Chem wet scavenging processes dramatically improved model-simulated nitric acid, nitrate, and ammonium over the US. However, further studies are needed to assess the impacts of the updated wet scavenging processes (UWSP) on other species and the performances of model simulation in other regions. In this work, we proposed new updates of rainout efficiencies and the uptakes by cirrus cloud in addition to ICCWV and EWR. We compared simulated surface mass concentrations of nitric acid, nitrate, ammonium, sulfate, black carbon, and organic carbon over the US and Europe and found that model running with the UWSP improved the agreement with measurements at these surface monitoring networks for most species. Observed annual mean surface mass concentrations of these species at EMEP sites are 0.7, 2.1, 1.0, 1.4, 0.5, 2.2 µg m-3, respectively. After considering the UWSP, these values are changed from 1.6 to 0.6, 5.2 to 2.6, 2.1 to 1.3, 1.4 to 1.2, 0.5 to 0.5, and 1.5 to 1.4 µg m-3, respectively. We also validated the simulated and observed nitric acid, nitrate, ammonium, and sulfate surface mass concentrations at EANET sites over East Asia. The comparison shown that normalized mean biases of these species are changed from 312 % to 67 %, 162 % to 43 %, 123 % to 64 %, and -1 % to -12 %, respectively. Furthermore, we compared model simulation with aircraft measurement of nitric acid and aerosols during ATom-1 and ATom-2 periods and found seasonal variation and vertical profile of these species have been successfully improved by considering the UWSP. The overestimations of nitric acid below 400 hPa during ATom-1 and ATom-2 and the underestimations of nitric acid above 300 hPa during ATom-1 have been reduced. The employment of UWSP also significantly reduced the overestimations of nitrate, ammonium, and sulfate during ATom-2 and the overestimations of nitrate above 400 hPa during ATom-1. The UWSP slightly enhanced simulated organic carbon above 700 hPa and made the values closer to the observation. Our study indicated that the UWSP can improve the skill of global modeling of nitric acid and various aerosols. The impact of UWSP on global mass loading of nitric acid and aerosols will be discussed.
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