Regional difference and catastrophe of climate change over Urumqi River Basin.

Based on climatic data of two stations in the Urumqi River Basin,methods of regression analysis and moving average were used to study the climatic changing trend of the study area under the background of global warming.Results showed that the temperature was relatively low in the 1960s,1970s and 1980s and high in the 1990s,in other words the temperature was in a decreasing trend before the 1980s and in a ascending trend after the 1990s due to the rise of temperature in autumn and winter;the precipitation of upstream river basin showed a downward trend from the 1960s to the 1980s,then showed the increasing trend obviously.Since the beginning of the 21st century,the precipitation increasing has especially been rapid.The precipitation of the downstream in the 1960s was little,then increased gradually,and quickly increased in 2000s.The temperature change in the lower reach area was more obvious than that in upper reach area.The warming trend in autumn and winter was more obvious than that in spring and summer.Also the precipitation in the upstream area was more than that in the downstream area,and the mountains area's more than plain's.What is more,methods of T test,YAMAMOTO(SNR),Mann-Kendall,Cramer and Pettitt were employed to analyze the climatic break,indicating that the abrupt changes of temperature and precipitation were not obvious in the study area,and different test methods had different results,however it showed that temperature in spring and summer had abrupt change in 1997.The temperature abrupt change in autumn and winter happened in the late 1980s and the early 1990s.The abrupt change of temperature in autumn and winter was earlier than that in spring and summer.The abrupt change of precipitation in the upstream area might occur in the 1990s,while the abrupt change of precipitation in the downstream area might occur in the late 1970s and the early 1980s,about 10 years earlier than that in the upstream area.