Wed Apr 16 04:31:35 UTC 2025: ## IIT Bombay Study Reveals Two-Part Mechanism Behind 2022 South Asian Heatwaves

**Mumbai, April 16, 2025** – A new study by researchers from the Indian Institute of Technology (IIT) Bombay and Johannes Gutenberg-University Mainz, Germany, has shed light on the unprecedented back-to-back extreme heatwaves that struck South Asia in March and April 2022. The research, published in the Journal of Geophysical Research: Atmospheres, reveals that the two events were caused by distinct yet interconnected atmospheric processes.

The March heatwave, the study found, was primarily driven by amplified atmospheric Rossby waves – large-scale wind patterns. These waves intensified as high-altitude westerly winds transferred energy to lower-altitude winds, leading to a surge in temperatures.

However, the April heatwave followed a different mechanism. Instead of wind patterns, it was largely attributed to extremely dry soil conditions and the advection of heat from the northwestern regions of Pakistan and Afghanistan. Crucially, the researchers found that the preceding March heatwave contributed to these dry conditions by depleting soil moisture through high temperatures and clear skies.

Lead author Roshan Jha explained that the dry soil created a feedback loop, exacerbating the April heatwave. When soil moisture is present, some solar energy is used for evaporation, reducing air temperature. But with dry soil, all the energy goes directly into heating the air.

Co-author Arpita Mondal highlighted the concerning implication: “One heatwave can set the stage for another, more intense heat event by removing moisture from the soil.”

Professor Subimal Ghosh, a co-author and Convener of IIT Bombay’s Centre for Climate Studies, emphasized the importance of understanding these mechanisms for improving heatwave forecasting and mitigation strategies in South Asia. He stated that as climate change impacts wind patterns, pinpointing these drivers is crucial for better prediction and preparedness. The study underscores the complex interplay of atmospheric dynamics and land surface conditions in driving extreme weather events.

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