A theoretical study of the wet removal of atmospheric pollutants. Part V: the uptake, redistribution, and deposition of (NH4)2 SO4 by a convective cloud containing ice

Abstract

The effect of an ice phase on the wet deposition of aerosol particles was studied by means of the authors' 2D cloud dynamics model with spectral microphysics applied to the Cooperative Convective Precipitation Experiment in Miles City, Montana, on 19 July 1981. The cloud macrostructure as well as the cloud microstructure simulated by the model was found to agree well with observations. Although no on-site observations were available with respect to the chemical composition of the cloud and rain water, the values predicted by the model compared well with typical nearby measurements. By purposely inhibiting ice nucleation but otherwise keeping all dynamic, thermodynamic, and microphysical input parameters the same, it could be shown that the changes in the microphysical structure of the cloud, which significantly altered both the time rainfall began and the rainfall duration, also significantly altered the wet deposition of chemical species. -Authors