Long term climatology and trends of heat waves over India during the recent 50 years (1961-2010)

Abstract

Using HW information of 103 stations from Indian main land during the hot weather season (March to July) for the last 50 years (1961-2010), various statistical aspects of heat waves (HWs) and severe heat waves (SHWs) such as long term climatology, decadal variation, and long term trends were examined. The link of HWs/SHWs with ENSO phenomena, which has known impact on the weather world over was also examined. It was observed that many areas of the country (north, northwest, central and northeast Peninsula) have experienced HW days of ≥8 HW days on an average per season. The SHW were mainly experienced over north, northwest and central parts of the country. Compared to previous four decades, there was noticeable increase in the HW/SHW days over the country during the recent decade 2001-2010, which is also the warmest decade for the country as well as for the globe. Significant long term increasing trends in HW days was also observed over India during the analysis period. About 25 stations from north, northwest and central India showed significant increasing trend in the HW days and 5 stations mainly from northwest India showed significant increasing trend in SHW days. However, few stations have shown significant decreasing trend in HWs (2 stations from north India & 3 stations from east coast) and SHWs (2 stations from east coast). In general, the frequency, persistency and area coverage of the HW/SHW days were found to be more than average during years succeeding El Nino (El Nino +1) years.