Extreme climate events impacting southwest coast, says study

Study analysed monsoon data from 1990 to 2023 to interpret how vertically integrated moisture flux influences rainfall patterns

India’s southwest coast has seen a steady rise in extreme rainfall events, increasing at a rate of 0.23 mm per season, according to a study by a team of researchers from the Cochin University of Science and Technology (Cusat), European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT), and the UK Met Office.

The research, which investigated monsoon rainfall data from 1990 to 2023 focusing on the west coast of India by analysing observational records, reanalysis data, and sea surface temperature (SST) trends, interpreted how vertically integrated moisture flux impacted rainfall patterns. Titled ‘Deciphering the Relationship Between Moisture Flux and Monsoon Extreme Rainfall Over the West Coast of India’, the study was published in the International Journal of Climatology.

“The study showed that the southwest coast has seen a steady rise in extreme rainfall events, increasing at a rate of 0.23 mm per season. This trend is strongly tied to the thermodynamic component of moisture flux, which itself correlates with warming SSTs in the southeast Arabian Sea,” according to Ajil Kottayil, scientist at the Advanced Centre for Atmospheric Radar Research, Cusat, who had guided the study authored by Tesna Maria, a doctoral scholar at the centre. The research was a collaborative effort with Dr. Viju John of EUMETSAT and Prince Xavier of the UK Met Office, he said.

Since 2014, SSTs in this region have consistently exceeded 28 degrees Celsius, creating a conducive environment for intensified moisture transport and subsequent rainfall. The northwest coast, while not showing a similar rise in extreme rainfall, has experienced an increase in average monsoon rainfall, which is linked to the strengthening of the dynamic component of moisture flux, according to the study.

Mr. Kottayil said that the study underscored the rapid warming of the Arabian Sea compared to the Bay of Bengal and the tight coupling between SST and moisture flux since 2006.

“The correlation, which was negative before 2006, strengthened to 0.71 during 2007–2023, indicating that recent warming in the southeast Arabian Sea has significantly enhanced thermodynamic moisture transport, particularly over the southwest coast. This makes the southwest coast, especially Kerala, particularly vulnerable to climate change, with extreme rainfall events likely to intensify in the coming decades,” he said.

Published - January 31, 2025 01:28 am IST