Improvement of the vertical humidity distribution in the chemistry-transport MATCH through increased evaporation of convective precipitation

Abstract

We compare the vertical monthly mean distributions of model water vapor from the Model of Atmospheric Transport and Chemistry (MATCH) to tropospheric in situ sonde profiles and to upper tropospheric water vapor climatologies from the Microwave Limb Sounder (MLS). We perform two model runs with and without increased evaporation of precipitation in midlevel downdrafts and subsidence regions of convective systems. We demonstrate that higher evaporation rates significantly improve the modelled vertical distribution of specific and relative humidity with respect to what has been observed, by moistening of mid and lower tropospheric levels in regions of strong convection. We further demonstrate that the more efficient evaporation increases the modelled water vapor residence time, reducing the gap to observed mean watervapor residence times from synergistic use of the Global Ozone Monitoring Experiment (GOME) water-vapor fields and data from the Global Precipitation Climatology Project (GPCP). Copyright 2005 by the American Geophysical Union.