Vertical Transport and Wet Scavenging of Aerosols in Deep Convection during SEAC4rs Case Study: A Modeling Approach

Deep convective clouds affect aerosol distributions and concentrations through vertical transport and wet scavenging. Aerosol wet scavenging is a complex atmospheric process and is a major source of uncertainty in atmospheric models , especially for parameterized convective clouds. This study uses the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) to simulate the wet scavenging of sulfate, ammonium, nitrate, and organic aerosol mass concentrations in convective storms observed on 2 September 2013 observed near Jackson, MS during the NASA Studies of Emissions and Atmospheric Composition, Clouds, and Climate Coupling by Regional Surveys (SEAC⁴RS) field campaign. Simulations using the WRF-Chem model configured with the MOSAIC aerosol representation at regional and cloud-permitting resolutions are being analyzed to evaluate the model’s ability to represent aerosol scavenging using the NASA DC-8 aircraft observations. To understand the role of scavenging processes and cloud chemistry on aerosol distributions, WRF-Chem sensitivity simulations are being conducted. The observed aerosol nitrate scavenging efficiencies were often less than those of other hygroscopic aerosols (e.g., sulfate and ammonium). Thus, WRF-Chem simulations are also performed to investigate the role of lightning production of nitrogen oxides in affecting aerosol nitrate concentrations. The outcome of the WRF-Chem analysis will give better insights into aerosol scavenging representation in convection for regional-scale and global-scale chemistry transport models.