Microphysical and thermodynamic structure and evolution of the trailing stratiform regions of mesoscale convective systems during BAMEX. Part II: Column model simulations

This study employed a nondynamic microphysical column model to evaluate the degree to which the microphysical processes of sublimation, melting, and evaporation alone can explain the evolution of the relative humidity (RH) and latent cooling profiles within the trailing stratiform region of mesoscale convective systems observed during the Bow Echo and Mesoscale Convective Vortex Experiment (BAMEX). Simulations revealed that observations of a sharp change in the profile of RH, from saturated air with respect to ice above the melting layer to subsaturated air with respect to water below, developed in response to the rapid increase in hydrometeor fall speeds from 1–2 m s−1 for ice to 2–11 m s−1 for rain.

However, at certain times and locations, such as the first spiral descent on 29 June 2003 within the notch of lower reflectivity, the air may remain subsaturated for temperatures (T) 0°C; thus, evaporation and melting result in the primary cooling in this region. The implications of these results for the descent of the rear inflow jet across the trailing stratiform region are discussed.