Potential impacts of aerosol pollution on precipitation and storm dynamics of a Derecheo-producing MCC

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Wednesday, 5 February 2014
Hall C3 (The Georgia World Congress Center )
Michal Clavner, Colorado State University, Fort Collins, CO; and W. R. Cotton and S. van den Heever

Mesoscale Convective Complexes (MCC) are important contributors to rainfall in the United States as well as producers of severe weather such as large hail, severe winds and tornadoes. The goal of this research is to understand the susceptibility of a Derecheo-producing MCC to the indirect effects of varying aerosol characteristics: size, concentration and chemical composition. This study investigates the indirect effects of anthropogenic aerosols on the different modes of convection that constitute an MCC and their subsequent impacts on severe wind formation in the storm. This was done by simulating an MCC in a spatially three dimensional heterogeneous field of anthropogenic aerosols using the Regional Atmospheric Modeling System (RAMS). The model simulations are performed using a triple nested-grid, where the finest grid contains the entire domain of the MCC, from genesis to decay. Convection and cloud-microphysics are explicitly represented in the simulated cloud development of the MCC. Different spatial configurations of aerosol concentrations were imported into RAMS from output of the GEOS-CHEM model: a three dimensional atmospheric model that includes emissions, formation and transport of different aerosol species. Both organic and inorganic aerosol species from GEOS-CHEM were incorporated into the RAMS simulations, where they serve as potential CCN. These runs were compared to a control run defined by spatially homogeneous clean aerosol concentrations.   It is hoped that by comparing the output of these simulations, advancements will be made in our understanding of the impacts of aerosol concentration, size and chemical composition on MCC dynamics.