Precipitation scavenging coefficient: influence of measured aerosol and raindrop size distributions

Precipitation scavenging coefficients, widely used in pollution studies, ar e derived from microphysical parameterisations of aerosol particles and rai ndrop populations and parameterisations of their interactions. The present study investigates the effects of measured aerosol and raindrop size distri butions in a microphysical polydisperse framework. The interactions between aerosol and raindrops parameterised as collision efficiency are explicitly included to account for Brownian diffusion, inertial impaction and interce ption. Estimated values of the polydisperse scavenging coefficients exhibit variations of orders of magnitude depending on the aerosol type and almost no variation with the raindrop size distributions. For practical use, line ar relationships between the scavenging coefficients and rain intensity for different aerosol types are derived. (C) 2000 Elsevier Science Ltd. All ri ghts reserved.