ICCS Seminar Series

📅 10 July 2026   |   🕒 11:30 AM – 12:30 PM   |   📍 ICCS Seminar Hall, Kottayam

Monsoon low-pressure systems (LPS) are a primary driver of extreme rainfall during the Indian summer monsoon. While most LPS form near the tropical convergence zone (active phase of monsoon), some develop even in its absence (break phases). Recent research reveals that changes in the dynamic intensity and rain rate of LPSs are not always captured by traditional metrics. For example, there is a strong association between LPS-induced rainfall and Indian Summer Monsoon Rainfall (ISMR): years with excess ISMR witness more frequent and/or intense LPS-related extremes, while drought years see weaker LPS rainfall. Excess-ISMR years are also marked by higher ambient humidity and stronger LPS-driven ascent, that cause the extreme large size extreme events. However, conventional dynamical intensity metrics for LPSs show limited variation, leading to a perceived mismatch between rainfall intensity and standard measures of LPS strength. This suggests a potential underestimation of dynamic contributions to enhanced rain rates. But stronger horizontal pressure gradients and higher near-center wind speeds result in more compact, intense LPSs during excess-ISMR years, clarifying the connection between LPS dynamics and extreme rainfall. Furthermore, LPSs originating over the Bay of Bengal, especially during periods of strong sea surface warming, tend to be more intense and produce wide extreme events over the Indian landmass. These findings highlight the need for refined analysis of LPS structure and region-specific rainfall impacts, contributing to improved understanding and prediction of extreme monsoon events.