Internal Structure and Development Processes of C-Scale Aggregates of Cumulus Clouds

Abstract

Law echoes (C-scale in GATE terminology., approximately 100 to 10 000 km2) seem to produce most of the precipitation that occurs in tropical systems. These large echoes are seen to last several hours and comprise many smaller and short-lived cells that grow and die within their bounds or are merged with them. In this paper, quantitative GATE radar data are used to statistically characterize these composite echoes as a whole, and to study their internal structure, formation and development processes. In addition, statistics of the individual cells making up the composite echoes are presented. These are compared to similar data for cells that develop individually away from the aggregates. In this way, some information is obtained about the duration, rain-producing ability and the size of those cells that merge to form larger groups compared to those clouds that form, develop and die relatively independently of one another.