Variation of Tropospheric Temperatures over India dining 1944–85

Abstract

Variation of air temperature at the surface and at four levels in the troposphere, viz., 850, 700, 500 and 200 mb, over India have been studied using the data at ten radiosonde stations for 31 to 42 years during 1944?85. Seasonal as well as annual mean temperature series have been obtained, and the general feature of the variations are discussed. Quantitative study of the temperature changes is made by evaluating the linear trends. Surface temperatures do not show appreciable trends during the last three decades over India, but at the upper levels there was a trend reversal around 1958, from warming to cooling. There is a distinct contrast between the northern and southern Indian stations during 1958?85, in that the former have shown significant cooling while the latter have shown no trends. Port Blair, the island station considerably south, however, shows slight cooling during this period. The rate of cooling increases with height, particularly at the northern stations. There is no marked interseasonal contrast in the temperature trends at upper levels.