The physics of extreme rainfall event: An investigation with multisatellite observations and numerical simulations. (August 2020)

• Record Type: Journal Article
• Authors: Meenu, S.; Gayatri, K.; Malap, Neelam; Murugavel, P.; Samanta, Soumya; Prabha, Thara V.
• Is Part Of: Journal of atmospheric and solar-terrestrial physics. Volume 204(2020)
• Publication Date: 2020-08
• Subjects: Extreme/heavy rainfall -- Kerala -- Cloud microphysics; Geophysics -- Periodicals; Atmospheric physics -- Periodicals; Géophysique -- Périodiques; Météorologie physique -- Périodiques; Electronic journals; 551.51
• DOI: 10.1016/j.jastp.2020.105275
• Languages: English
• ISSNs: 1364-6826

Abstract

Abstract: An extreme rainfall event that made major calamity over the Indian peninsula region has been investigated with a focus on the physics of the cloud system as indicated from the multi-satellite observations, ground-based radar, and model forecast experiments. The vertical structure of clouds showed deep convective cores embedded in the stratiform and is dominated by warm and mixed-phase clouds. Model output indicates that moisture convergence was present in two episodes before both heavy rainfall events, and can be used as a precursor for the imminent heavy rainfall. It is the sustenance of high winds and availability of moisture content that contributed to the development of deep convective cloud bands which propagated inland, perpendicular to the coastline. These cloud systems produced deep convective cores with a deep supersaturated layer throughout the middle and upper atmosphere, introduced a significant amount of supercooled liquid water, which facilitated mixed-phase clouds. These cloud liquid drops at supercooled temperatures facilitated the production of more ice hydrometeors on freezing. The rapid growth of hydrometeors through riming and aggregation in the mixed-phase region lead to heavy and sustained precipitation. The sustenance of the system is also due to the enhanced latent heating over Western Ghats that supported low-level moisture convergence in a strongly sheared environment. Documented evidence from this study suggests that the heavy precipitation was a result of the convective cluster as illustrated through satellite observations and numerical simulations. Highlights: Physics of cloud systems associated with heavy rainfall event in a coastal location; Kerala. Combined multi-satellite observation and numerical analysis. Precursor of extreme rainfall events. Cloud systems with deep convective cores dominated by warm and mixed-phase. Orientation of the propagating cloud bands over land and sea.