Response of Cumulus Updraft and Downdraft to GATE A/B-Scale Motion Systems

Abstract Large-scale mass, heat and moisture budgets have been computed over the GATE A/B-scale area during two priority periods in Phase 3. The computed budget results are well-correlated with the activities of the cloud clusters which develop and decay during the analyzed period. Strong upward motion exists with two maxima at 700 and 350 mb during the active period of the cloud cluster, but sinking motion appears in the middle troposphere during the dissipating period. Large amounts of apparent heat sources and moisture sinks occur in the whole troposphere and large amounts of heat energy are transported upward by cumulus clouds during the active period; but an apparent heat sink, moisture source and slight downward heat flux are observed in the middle troposphere during the dissipating period. A diagnostic method for determination of cloud properties has been improved by including downdraft effects and tested on the mean Marshall Islands data. In this method both spectral properties of updrafts and bul...