Increase in spatial spread of extreme warm day temperature events: regional to national perspective for India (1951-2014)

Abstract

The present study analysed high-resolution quality checked gridded temperature datasets of India Meteorological Department for the duration of last six decades over India and its different agro-climatic zones to determine the changes in land area affected by extreme warm day temperatures. The results indicate an unequivocal increase in area influenced by different levels of extreme warms days over the country; the rate was higher and statistically significant during the last three decades. The increase in land area affected by extreme-of-extreme temperature events occurred at a higher rate compared to the low-frequency extremes. Robust statistical tests indicated clear change in the probability distribution of the land area affected by extremes, signifying that comparatively high-frequency extremes are occurring in larger areas. The results do indicate a strong regional dissimilarity, with five agro-climatic zones (ACZ-02, 09, 10, 11, 12) covering North East India, western and southern plateau and hills along with both the coastal plains showing increase in land area under most levels of extremes, and three agro-climate zones (ACZ-08, 13, 14), the central plateau, Gujarat plains and western dry region showed increase in land area for a few extreme levels.