The Vertical Distribution of Heating in AMEX and GATE Cloud Clusters

Abstract

Tropical cloud clusters that occurred during the Australian Monsoon Experiment (AMEX) are composited and compared to a composite of the GARP Atlantic Tropical Experiment (GATE) systems. The analysis focuses on the evolution of the life cycles and upon the vertical heating profiles. The AMEX and GATE systems were of comparable duration and magnitude, although the former produced more rainfall. However, AMEX convective systems produced maximum heating in the middle troposphere and showed only small variations in the heating with height. In contrast GATE systems began with heating concentrated in the lower troposphere and exhibited a marked upward shift in heating with time. GATE systems always had greater fractions of their total heating at lower levels than did AMEX systems, presumably due to differences in the large flow. The vertical stratification of the atmosphere in both regions resembles that of a reversible moist adiabat at lower levels and of a pseudoadiabat above the freezing level. This agrees with results of recent studies of the tropical regions. During the life of the convective system, the atmosphere adjusts slightly toward these adiabats. This suggests that the abundant deep convection in the AMEX and GATE regions maintains the stratification near an equilibrium profile.