Observational evidence of increasing compound tropical cyclone-moist heat extremes in India

Abstract

Moist heat stress can lead to the inability of the human body to cool itself due to the impact of high temperature and humidity. The co-occurrence of tropical cyclones (TCs) and moist heat stress has considerable implications for India's dense population and infrastructure. However, the crucial linkage between TCs and moist heat extremes remains unrecognized. We used the cyclone eAtlas and ERA5 reanalysis to examine the temporally compounding TC and moist heat extremes over India from 1980 to 2021. We find that TC-Heat stress events in India have increased recently, which can be attributed to the high-intensity TCs originating from the Arabian Sea. The risk of TC-Heat stress events is higher (than in other parts of the world) in India due to an overlap of peak moist heat and TCs occurrence during the pre-monsoon (April-June) season. Landfalling TCs alter the thermodynamic environment causing the moist heat to peak over the region with increased frequency and intensity. The direct and compounded influence of TCs on moist heat can have substantial implications.