Investigating the impacts of dust and anthropogenic emissions on indirect aerosol effects in convective clouds in the Southern Great Plains

Concentrations of anthropogenic air pollutants such as ozone and atmospheric aerosols are magnified in urban areas. Aerosols have direct, indirect and semi-direct effects on the atmospheric radiation budget and the formation, presence and persistence of clouds in the atmosphere. Depending on environmental factors such as vertical wind shear and relative humidity, aerosols can either suppress or enhance convection. We isolate the effects of urban emissions on convective events in the Southern Great Plains with WRF-Chem . Understanding convective events in the Southern Great Plains in the spring can provide insight into thresholds for whether convection is suppressed or enhanced in a region dominated by strong vertical wind shear, regular severe weather events, and varying levels of urbanization. While anthropogenic effects in this region are relatively small, we focus on the urban areas of Kansas City, MO, Oklahoma City, OK, and Wichita, KS, which represent moderate to high, low to moderate, and low levels of pollution respectively. To isolate the chemical effects of urban pollution on convective cloud dynamics and microphysics, we produce month long simulations in May 2013 using the WRF-Chem model using three emissions scenarios: the first simulation (BASE) includes the physical and chemical effects with prescribed dust and normal emissions. The second simulation uses prescribed dust and scales emissions by a factor of two and the third simulation prescribes dust and scales emissions by a factor of one half. Together, these simulations show the role of dust and anthropogenic pollution on regional severe weather events.