Analysis of Climate Change in Tibetan Plateau over the Past 40 Years

With the combination of sunshine duration,annual mean air temperature,pan evaporation and precipitation,features of climate change in the Tibetan Plateau over the past 40 years are investigated,using time series analysis as well as non-parametric Mann-Kendall test.The major findings include:⑴For daily sunshine duration, the northwestern part of the Plateau is longer than that of in the southeastern part.A decreasing trend is detected in the southeast,and an increasing one in the northwest;⑵The study area is divided into three sub-regions with the 0 ℃ and 5 ℃ annual mean air temperatures.As far as the whole plateau is concerned, an increasing trend is found for annual mean air temperature,with a change value even greater in the west;⑶The change in annual evaporation is also obvious,with a decreasing trend detected for the whole area.And as a whole,the evaporation goes down from west to east;⑷For precipitation, the basic rules of its spatial distribution are:the changing extent decreases from east to west;an increasing trend is identified in the middle and eastern parts,but a decreasing trend is distinct in the west.In addition, the monthly and seasonal changes in terms of the four climatic elements are consistent with annual change.