Large‐scale connection to deadly Indian heatwaves. (15th February 2021)

• Record Type: Journal Article
• Authors: Rao, V. Brahmananda; Rao, K. Koteswara; Mahendranath, B.; Lakshmi Kumar, T. V.; Govardhan, D.
• Is Part Of: Quarterly journal of the Royal Meteorological Society. Volume 147:Number 735(2021)
• Page Start: 1419
• Page End: 1430
• Publication Date: 2021-02-15
• Subjects: Arctic amplification -- heatwaves -- planetary Rossby waves -- quasi‐resonant amplification (QRA); Meteorology -- Periodicals; 551.5
• DOI: 10.1002/qj.3985
• Languages: English
• ISSNs: 0035-9009

Abstract

Abstract: In the present study, we analyse large‐scale connections to deadly heatwaves in India in spring. Deadly Indian heatwaves occur in the spring months of April and May, and are increasing in recent years. These events are associated with the amplification of planetary Rossby waves. This amplification is called quasi‐resonant amplification (QRA). An increase of amplitude or resonance occurs when stationary and moving waves coincide in their size. Previous studies stressed QRA's role in summer because persistent extreme weather events such as the 2003 European heatwave, the 2010 Pakistan flood, Russian heatwave, the 2011 Texas and Oklahoma heat waves, and drought occurred in summer. QRA seems to be related to the amplification of Arctic warming in winter and summer, but observations show that Arctic warming occurs in spring also. The novel aspect of our study is that we found strong evidence for QRA in the boreal spring, the season of Indian heatwaves. Amplified Arctic warming or Arctic amplification thought to be responsible for QRA occurs in spring also. Our results confirm that maximum surface temperatures in spring over India show predictability with high statistical significance, about 4 days ahead. Maximum surface temperatures can be used to predict heatwaves, as shown earlier by some authors. Abstract : In the present study, we analyse large‐scale connections to deadly heatwaves in India in spring. Deadly Indian heatwaves occur in the spring months of April and May, and are increasing in recent years. These events are associated with the amplification of planetary Rossby waves. This amplification is called quasi‐resonant amplification (QRA). An increase of amplitude or resonance occurs when stationary and moving waves coincide in their size. Previous studies stressed QRA's role in summer because persistent extreme weather events such as the 2003 European heatwave, the 2010 Pakistan flood, Russian heatwave, the 2011 Texas and Oklahoma heat waves, and drought occurred in summer. QRA seems to be related to the amplification of Arctic warming in winter and summer, but observations show that Arctic warming occurs in spring. The novel aspect of our study is that we found strong evidence for QRA in the boreal spring, the season of Indian heatwaves. Amplified Arctic warming or Arctic amplification thought to be responsible for QRA occurs in spring also. The amplitude of the meridional wind for wave numbers for different events and climatology.