Synopsis
IIT Bombay researchers have identified various climatic factors causing repeated extreme heat waves in South Asia, particularly affecting India, Pakistan, and Afghanistan. Their findings highlight the complex interplay of atmospheric processes and soil conditions contributing to these severe weather events.Key Takeaways
- Identification of climatic drivers behind extreme heat events.
- Impact of Rossby waves on heatwave intensity.
- Influence of dry soil conditions on subsequent heatwaves.
- Understanding heatwave mechanisms for better forecasting.
- Need for improved prediction and mitigation strategies.
New Delhi, April 14 (NationPress) Researchers at the Indian Institute of Technology Bombay (IITB) have identified various climatic factors contributing to the series of extreme heat events affecting South Asian nations, including India, Pakistan, and Afghanistan.
This investigation, conducted in partnership with experts from Johannes Gutenberg-University Mainz in Germany, concentrated on the unusually severe heatwave occurrences in March and April of 2022.
The research team discovered distinct atmospheric mechanisms that exacerbated the effects of the heatwaves, resulting in temperatures significantly higher than the typical values for that time of year.
“Our study indicates that the March heatwave was primarily associated with a sudden rise in the intensity of short-lived atmospheric Rossby waves, which are large-scale meanders in high-altitude winds resembling bends in a winding river,” stated lead author Roshan Jha, a doctoral candidate at the Centre for Climate Studies, IIT Bombay.
“The waves intensified as high-altitude westerly winds near the poles (extratropical jet stream) transferred energy to westerly winds closer to the equator (subtropical jet stream) as they converged during the heatwave,” Jha elaborated.
This research, published in the Journal of Geophysical Research: Atmospheres, indicated that the April heatwave originated from different dynamics. Rather than being influenced by high-altitude wind patterns, it was predominantly driven by extremely dry soil conditions and the transfer of heat into India from the north-western land areas of Pakistan and Afghanistan.
Significantly, these arid conditions were partially caused by the preceding March heatwave, which had already desiccated the soil due to high temperatures and clear skies.
The findings highlight a troubling trend: one heatwave can pave the way for another, more severe heat event shortly after by depleting soil moisture. Once soil becomes excessively dry, it initiates a cycle that amplifies the severity of subsequent heatwaves.
“Consider this — when the soil retains moisture, under clear sky conditions, a portion of the sun's energy is utilized to evaporate that moisture instead of warming the air. However, when the soil is already dry, all that energy directly contributes to raising the air temperature,” clarified co-author Prof. Arpita Mondal, Associate Professor at IIT Bombay.
The researchers emphasized the necessity of comprehending these mechanisms to enhance the forecasting and preparation for extreme heat events in South Asia. This understanding will also facilitate better prediction and mitigation of the consequences of future heatwaves.
