The effects of clouds on aerosol and chemical species production and distribution 2. Chemistry model description and sensitivity analysis

Abstract

A modeling study of the effects of cumulus convection on the transformation and redistribution of chemical species in the troposphere is described. A sulfate chemistry model is coupled with a two-dimensional, mixed-phase, two-moment microphysics Eulerian cloud model to examine the importance of different pathways for aqueous sulfate production. The complexation of CH2O with S(IV) was found to be of minor importance in most of the model cloud, compared with the oxidation of S(IV) by H2O2 and O3, while Fe(III)-catalyzed oxidation plays an important role in aqueous phase sulfate production. Significant redistribution of SO2 from the boundary layer to the middle and upper troposphere was predicted, with a larger percentage redistributed in cases initialized with chemical fields representative of polluted continental conditions. The sensitivity of the S(IV) production and SO2 redistribution to variations in several model parameters is also examined.