Parameterization of the Vertical Transports Due to the Cumulus Convection Using a Mass-Flux Scheme

Updraft and downdraft penetrative convective motions are taken into account for a pollutant cloud evolution. The parameterization is based on Tiedtke’s (1989) mass-flux scheme. Cumulus convection contribution to large-scale pollutant concentration tendency is function of the net contribution from all clouds to the upward and downward mass-flux, a weighted average of c (pollutant concentration) from all updrafts and downdrafts and large-scale transport contribution (precipitation impact is parameterized following Piedelievre et al., 1990). The amount resulting from evaporation of precipitation in the unsaturated subcloud layer is also included in computation (evaporation due to the downdraft and detrained cloud air is not considered for the concentration amount).