Evaluation of temperature trends over India

The impact of climate change is projected to have different effects within and between countries. Information about such change is required at global, regional and basin scales for a variety of purposes. An investigation was carried out to identify trends in temperature time series of 125 stations distributed over the whole of India. The non-parametric Mann-Kendall test was applied to detect monotonic trends in annual average and seasonal temperatures. Three variables related to temperature, viz. mean, mean maximum and mean minimum, were considered for analysis on both an annual and a seasonal basis. Each year was divided into four principal seasons, viz. winter, pre-monsoon, monsoon and post-monsoon. The percentages of significant trends obtained for each parameter in the different seasons are presented. Temperature anomalies are plotted, and it is observed that annual mean temperature, mean maximum temperature and mean minimum temperature have increased at the rate of 0.42, 0.92 and 0.09degreesC (100 year)(-1), respectively. On a regional basis, stations of southern and western India show a rising trend of 1.06 and 0.36degreesC (100 year)(-1), respectively, while stations of the north Indian plains show a failing trend of -0.38degreesC (100 year)(-1). The seasonal mean temperature has increased by 0.94degreesC (100 year)(-1) for the post-monsoon season and by 1.1degreesC (100 year)(-1) for the winter season.