全球变化知识资源中心

The absence of continuous long term meteorological dataset has led to limited knowledge of glaciers' response to climate change over Himalayas. This study presents an open source long term temperature dataset Climatic Research Unit (CRU) available since 1901 to study trend analysis of temperature (T-max,T- T-min and T-mean) for Gangotri basin in Himalayas. The study first establishes close agreement between CRU time series data and observed temperature dataset available from National Institute of Hydrology (NIH), Roorkee for a period of 11 years from 2005 to 2015 using standard anomaly, Wilcoxon Signed-Rank (WSR) and correlation tests. The close agreement of CRU with NIH data validate the use of CRU time series to study variation in meteorological parameter for hilly terrain of Himalayas. The second part includes application of different statistical tests such as Mann-Kendall (MK), Sen's slope and CUSUM technique on CRU data to detect existence of any possible trends and identification of change points in T-max,T- T-min and T-mean on long term scale. On annual scale, significant increasing trends for T-mean and T-min were observed with no significant trend for T-max. On seasonal and monthly scale, T-max showed significant decreasing trend for monsoon season and increasing trend for winters while T-min show significant increasing trend for all months (except May) and seasons. CUSUM technique identified 8 change points from 3 annual time series with 2 for T-mean (1974 and 1999), 3 each for T-max (1941, 1975 and 1999) and T-min (1941, 1965 and 1999) respectively. Overall, significant increase in T-max with no significant trend for T-max has been identified over the study area.