Deep Convection-Aerosol Interactions using a Double Moment Convective Cloud Microphysical Scheme in the Kain-Fritsch Convection Parameterization

In regional and global models, deep convection parameterization schemes use simple microphysics for conversion of cloud liquid water to rain drops. Because of the lack of a detailed representation of all cloud microphysical processes in these deep convection parameterizations, aerosol and deep cloud interactions cannot be studied. To facilitate the deep convection-aerosol interactions, a double moment convective cloud microphysical formulation has been implemented directly into the Kain-Fritsch convection parameterization available in the WRF model.

WRF model simulations using 12 km grid spacing were performed using a multi-scale version of the Kain-Fritsch scheme for the summer of 2006 over the continental US. In the first simulation, the default simple autoconversion scheme was used. A second set of simulations used a double moment convective microphysical scheme with varying aerosol concentrations. In the last simulation, climatological profiles of aerosol concentrations were used.

We find that model-predicted parameterized convective precipitation decreases with increased aerosol concentrations. Observed precipitation amounts and distributions are compared with each of these simulations and these results will be presented.