The Life Cycle of a Stationary Cloud Cluster during the Indian Summer Monsoon: A Microphysical Investigation Using Polarimetric C-Band Radar

• Published in: Monthly weather review 2021-11, Vol.149 (11), p.3761-3780
• Main Authors: Samanta, Soumya, Murugavel, P., Gurnule, Dinesh, Rao, Y. Jaya, Vivekanandan, Jothiram, Prabha, Thara V.
• Format: Article
• Language: English
• Subjects: Agglomeration; Aggregates; Aggregation; C band; Cloud microphysics; Clouds; Clusters; Convective cells; Convective clouds; Crystal structure; Crystals; Cumulus clouds; Electrification; Hail; Hydrometeors; Ice; Ice crystals; Life cycle; Life cycles; Melting; Monsoons; Polarimetric radar; Polarimetry; Radar; Rain; Raindrops; Rainfall; Summer; Summer monsoon; Tropical climate
• ISSN: 0027-0644; 1520-0493
• DOI: 10.1175/MWR-D-20-0274.1

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.