In this work, the role of latent cooling on MCS structure and evolution is being investigated using the WRF model.  This study has been motivated by and is intended to compliment results from the BAMEX project, during which U. Illinois scientists carried out microphysical measurements of MCSs.

A 2-km control simulation under high CAPE and shear is shown at right.  The simulation was then repeated by restarting from the control simulation at different stages of the MCS life cycle, but with modified cooling contributions from evaporation, melting, and sublimation. 

The objective is to assess the role of microphysical cooling during various stages of MCS evolution, such as the onset of trailing stratiform region (TSR) development, and the formation and intensification of the rear inflow jet (RIJ).

Metrics to assess MCS structure include vertical velocity maxima, cold pool structure, areal extent of the TSR, areal coverage of vertical velocity and hydrometeor fields, etc.

Trajectory analyses are planned to study the time evolution of contributions of latent cooling for parcels bound for various regions in the MCS.  Higher horizontal and vertical resolution and a repeat of these experiments using a different microphysical scheme are planned as this study continues.

Future work will assess these findings under conditions of varied instability and vertical wind shear.

Some early results from this study were shown at the 2007 Mesoscale Processes conference (Waterville Valley NH).

This work is supported by the National Science Foundation under grant NSF ATM-0413824 (Robert Rauber, lead PI; Greg McFarquhar, co-PI).