Spatiotemporal variability of weather extremes over eastern India: evidences of ascertained long-term trend persistence and effective global climate controls

The present study acknowledged climate variability induced periodic variation in localized extreme weather event occurrences under diverse agro-eco regions of Eastern Himalayas of India during the past five decades. The widespread rise in warm nights (TN90p; 0.31-1.67 days year(-1)), reduced daily rainfall intensity (SDII), and changes in other weather extremes, viz. temperature and precipitation extremes, signified clear signals on regional atmospheric warming across eastern India. The agro-ecological regions under extended Bramhaputra valley and coastal belts of south Bengal experienced the most persistent shifts in temperature extremes, while the upper Himalayan range extended from North Bengal to Arunachal Pradesh experienced the steepest decline in average daily rainfall intensity and other absolute quantitative estimates of precipitation extremes over past five decades. Together with El Nino and La Nina events, large-scale global atmospheric circulations particularly expansion of warmer Pacific Warm Pool (PWP) and changes in Atlantic Meridional Mode (AMM) contributed to the periodic dynamics in weather extreme occurrences from monthly to annual time scale over eastern India. Our findings will be useful for better understanding of regional climatology, designing, and successful implantation of location-specific suitable agricultural policies towards climate change adaptation in near future.

Automated summary

The present study found that climate variability has led to periodic variations in extreme weather events in the Eastern Himalayas region of India over the past five decades. Warm nights have increased, daily rainfall intensity has decreased, and other weather extremes have changed, indicating clear signs of regional atmospheric warming across eastern India. The agro-eco regions in the Bramhaputra valley and coastal belts of south Bengal experienced the most persistent shifts in temperature extremes, while the upper Himalayan range from North Bengal to Arunachal Pradesh has seen the steepest decline in average daily rainfall intensity and other measures of precipitation extremes. Large-scale global atmospheric circulations, including the expansion of the Pacific Warm Pool and changes in the Atlantic Meridional Mode, in addition to El Nino and La Nina events, have contributed to the periodic dynamics in weather extremes in eastern India. These findings will be useful for understanding regional climatology and designing location-specific agricultural policies for climate change adaptation in the future.