Satellite derived mixing ratio profile, a resourceful indicator of heat waves: INSAT-3DR sounder based analysis

Abstract

India, being a tropical country, frequently experiences a natural hazard called heat waves especially during the hot summer season. During the summer months of 2022, India experienced moderate to severe heat waves spanning March to the third week of May. This adverse weather situation severely affects the northwest and the central Indian regions, causing loss of human lives, crop damage, and a scarcity of water. The present study is the first attempt to assess the meteorological situations favoring heat waves using Indian National Satellite (INSAT)-3DR sounder data. Such studies using satellite based sounder data have seldom happened. The study is conducted during March-May 2022 using the mixing ratio data derived from the INSAT-3DR sounder at 500 hPa, 620 hPa, 700 hPa, 850 hPa, and 950 hPa pressure levels of the atmosphere. From the present study, it is observed that the INSAT-3DR derived mixing ratio profile gives clear signatures of an impending heat wave condition. The weather signal can be observed as an apparent dryness representing the low mixing ratio values (<6 g/kg) percolating from upper layers (600 hPa) to lower levels (850 hPa). These percolations (seeping) happen prior to the surface layers actually show the effects of the heat wave. The study verifies the prior studies of heat wave strike over northwest frontiers of Indian land mass and its further expansion to eastern and southern regions. During strong heat wave conditions surface temperatures reaching maximum of 46 ͦ C at northwest regions, 41 ͦ C at eastern regions and 40 ͦ C at southern regions. The corresponding mixing ratio values at 950 hPa diminishes to 2–4 g/kg for northwest regions and 4–6 g/kg at eastern and southern regions. The study also gives hints to locate signals of heat waves regarding their origin, possible expanding directions, and geographical extent from the satellite-derived mixing ratio. The observations from the analysis give scope for further enhancing the study in the future to devise efficient forecasting methodologies to predict heat wave conditions using satellite derived mixing ratio profiles.