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Large‐Scale Extreme Rainfall‐Producing Synoptic Systems of the Indian Summer Monsoon
Author(s) -
Nikumbh Akshaya C.,
Chakraborty Arindam,
Bhat G. S.,
Frierson Dargan M. W.
Publication year - 2020
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2020gl088403
Subject(s) - climatology , monsoon , environmental science , low pressure area , vortex , convection , atmospheric sciences , flood myth , extreme weather , tropical cyclone , meteorology , geology , climate change , oceanography , geography , atmospheric pressure , archaeology
In recent years India has been increasingly experiencing widespread floods induced by large‐scale extreme rainfall events (LEREs). LEREs are mainly associated with monsoon low‐pressure systems (LPS). The forecast of these high‐flood‐potential events, however, has remained challenging. Here, we compare LPSs of the summer monsoon that led to LEREs (LPS‐Lg) and strong LPSs that did not result in LEREs (LPS‐noLg) over central India for the period 1979–2012. We show that having a strong LPS is not a sufficient condition to produce LEREs, and the LPS‐Lgs are accompanied by secondary cyclonic vortices (SCVs). The simultaneous existence of an LPS and an SCV creates a giant midtropospheric vortex. SCVs enhance dynamic lifting, static instability, and moisture transport from the Arabian Sea that precondition the atmosphere for deep convection. SCVs also slow down the propagation of LPSs. We show that the interaction of synoptic‐scale systems can lead to LEREs even if individual systems are not strong enough.