资源环境科技发展态势分析平台

Heat waves are studied to understand their regional vulnerability, causation over the Indian subcontinent in the context of the current global warming scenario. An updated, high resolution gridded surface air temperature data sourced from the India Meteorological Department (IMD) for the recent 65-year period (1951–2015) is used to ascertain the regions of maximum temperatures and heat wave vulnerability during the hottest month of May. Results reveal three distinct regions of maximum temperatures, over West Rajasthan in Northwest, North Madhya Pradesh and Southwest Uttar Pradesh in North-central, and East Maharashtra in South-central parts of India based on both the magnitude and frequency days of maximum temperatures. Contrastingly, three localised regions of heat wave vulnerability were identified in the north, northeast and southeast parts of India incontrovertibly different from the three maximum temperature zones. Soil temperature data confirm the regions of the maximum temperatures and the heat waves indicating the accentuation due to local radiative heating. The causation of heat waves was identified as the advection of heat by anomalous southwest, west and northwest wind flow from the three maximum temperature zones. Heat waves over southeast India, manifesting since 1970 denote the impact of global warming in recent decades. Climate model simulations of the current climate conform with the observed maximum temperature zones indicating the role of radiative heating. This study discerns the regions of maximum temperatures and heat wave vulnerability and identifies the causation to be triggered by wind flow from the maximum temperature zones under favourable atmospheric circulations. Results from this study would find wide application not only in the prediction, but also in the risk and vulnerability assessment.