Abstract
Multiplatform observations of the life cycle of a tropical continental mesoscale cloud cluster (CC) during the Indian summer monsoon, which contributed more than ~70 mm of rainfall over the arid peninsular Indian region, are presented in this study. The CC was characterized by a deep warm cloud layer with isolated convective cells in the initiation phase, merging of several deep cumulus clouds (~6 km) during the mature phase, growing up to ~15 km with mixed-phase and ice-phase cloud microphysical processes. Throughout the life cycle of the CC, polarimetric radar analyses revealed size sorting of falling raindrops, growth of dendritic particles, riming, aggregation, the occurrence of a saggy bright band, etc. The formation of big raindrops is observed during the initial convective rain, associated with the melting of hail. The stratiform counterpart is primarily associated with aggregates, ice crystals, and melting snow, resulting in surface rainfall. Aggregates are found to be the spatially dominant hydrometeor followed by ice crystals. The presence of vertically oriented ice crystals indicates active cloud electrification processes during the spatial aggregation of convective clouds. The dominant microphysical processes and precipitation pathways are illustrated. The study forms a benchmark case for model intercomparisons and evaluations.
Significance Statement
Cloud clusters are responsible for a significant amount of precipitation throughout the world and often result in catastrophic rainfall events, which cause a severe threat to life and livelihood. Understanding the microphysical evolution during the life cycle of the cloud clusters is crucial for their accurate simulation/prediction in numerical models. The complete life cycle of a stationary tropical continental mesoscale cloud cluster during the Indian summer monsoon is presented here using multiplatform observations. The study portrays the chronological sequence of events, and provides insights into the microphysical processes and pathways of precipitation during each phase of its life cycle.
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