A numerical study of aerosol-cloud interaction during a deep convective episode

Description

The coupled Weather Research and Forecasting-Chemistry (WRF-Chem) model is used here to study the extent of the indirect effect of aerosols on deep convective precipitation. The focus of the study is the Midwestern United States of America, where the squall lines produce intense weather during the warm summer months. Since precipitation is a highly non-linear process, and involves many processes, getting the state variables right is of utmost importance. The results suggest that the choice of vertical and horizontal resolution has a large contribution while simulating a deep convection. Comparisons with ground-based observations made at the ARM SGP site also support this point. Sensitivity analysis using the 2005 National Emission Inventory (NEI) emission data sets allows the indirect effect to be studied with the emissions for a typical summer day. The hypothesis being tested is the increase of convective strength and large-scale formation of clouds with increase in aerosols. Convection is driven by the increase in the updraft; the rapid transfer of aerosols and water vapor to higher levels causes them to release latent heat at higher levels, thus strengthening the convection.