Scavenging by convective and stratiform precipitation in MOCAGE
Résumé
The scavenging of soluble species is essential to a good representation of atmospheric chemical composition. The impact of wet deposition can be broken down as a function of the precipitation: convective or stratiform, and of its state: liquid or solid. In Météo France's multiscale chemical-transport model MOCAGE, in-cloud convective scavenging is separated from stratiform scavenging. The first part of this work consisted of a recalculation of 3D stratiform precipitation fluxes. Mari's [2000] scheme was then introduced to describe the wet deposition in the updraft, simultaneously with the convection. For stratiform precipitation, a first order scheme [Giorgi and Chameides, 1986] was used. This scheme was applied to convective below-cloud precipitation as well. This complete scavenging description has been tested by simulating Lead 210 concentrations during one year. This species, which is Radon 222's radio-active daughter, is chemically inert but highly soluble. The simulated concentrations are compared to worldwide observations, both at the ground and at altitude. [no pdf]
