Variations and Distribution of Precipitation of Gannan Based on DEM during the Period of 1983-2012

Based on the monthly precipitation data of Gannan municipality during the period of 1963-2012,Combined with 1:25 million geographic information data,According to the principles of mountain climatology and the climate change trend was analyzed by using linear fitting method,singular spectrum analysis of multi scale decomposition,spatial interpolation and climate abrupt change. The result showed that the average of precipitation descended obviously with the rate of 6. 3mm /10 a over recent 30 years. There are cycles of main period is 12 months and 6 months. The climate abrupt change year is 1985 and especially in the year of 1997 and 2002,precipitation descended significantly,more than 0. 05 critical line.