Geographical trapping of synchronous extremes amidst increasing variability of Indian summer monsoon rainfall

Abstract

Concurrent extreme rainfall events, or synchronous extremes, during Indian Summer Monsoon Rainfall (ISMR), cause significant damage, but their spatiotemporal evolution remains unclear. Using the event synchronization approach to examine the synchronicity of extreme rainfall events from 1901 to 2019, we find that central India consistently hosts strongly connected synchronous extreme hubs with localized connections, indicating the geographical trapping of these concurrent events in the region. We observe a moderate positive correlation between network cohesiveness and El Ni˜no Southern Oscillations (ENSO), and a negative correlation between ENSO and link lengths, suggesting localized synchronicity during El Ni˜no dominant decades and opposite patterns in La Ni˜na periods. Despite increasing ISMR variability and spatial nonuniformity, the persistence of hubs and network attributescould offer insights for predicting synchronous extremes, informing effective adaptation and risk management strategies during the monsoon season.