Thermodynamic Effects of Mesoscale Convective Systems on the Environment over the Eastern Atlantic

Abstract

Distributions of composited convective heating and drying vary substantially during the life cycle of six cloud clusters identified by Frank (1978) in Phase III of GATE. Convective heating (Q₁-Q_R) and drying (Q₂) begin in the lower troposphere. As cloud clusters mature, intensification of upper level convective heating increases; while below 600mb drying accompanies decreases in convective heating. The upper level convective heating reaches its peak, when the upper level cloud cover is largest; whereas the Q₂ maximum at 850mb coincides with the peak radar echo intensity. The depletion of moist static energy (Q₁-Q₂-Q_R) in the lower trposphere begins in the growing stage; whereas the upper level heating due to vertical eddy fluxes is most significant in later stages, when deep clouds are prominent.