Parameterization of below-cloud scavenging of highly soluble gases under convective conditions

A model is developed to compute below-cloud scavenging coefficients during rain of irreversibly soluble gases under convective circumstances. The model takes evaporation of raindrops into account. All results are parameterized as functions of the temperature, relative humidity, rainfall rate at ground lever and diffusivities of the gases at 25%. Functions are also found for the cloud base height, the smallest drop that can reach the ground and the amount of rain evaporated between the cloud base and the ground. The results are presented in such a way that they can easily be used in atmospheric transport models. Examples are given for NH3, HCl, H2O2, HNO3 and N2O5.