A Composite Model of Mesoscale Convective Complexes

Abstract

A composite analysis technique is used to investigate the evolution of mesoscale features of mesoscale convective complexes (MCCs). The early stage of the MCC lifecycle is characterized by convergence, vertical motion and heating being centered in the lower troposphere. As the MCC matures the level of peak upward motion and heating shifts to the upper troposphere. The system achieves and maintains its maximum divergence, upward motion, and anticyclonic vorticity in the upper troposphere during the latter half of the life cycle. This is in contrast to GATE tropical clusters where the maximum divergence, upward motion, and anticyclonic vorticity occurred at the mature stage of the cluster and then weakened. This difference might be explained by an MCC being an inertially stable form of mesoscale convective system whose radius exceeds the Rossby radius of deformation. The MCC is shown to be an efficient rain producer, exhibiting a precipitation efficiency exceeding 100% at the mature stage due to the accumulation of water substance in the stratiform anvil cloud during the earlier, predominantly convective stages of the system.