Abstract: In this paper, the variation of annual precipitation in Huangnan Prefecture was analyzed based on the precipitation data observed by 4 meteorological stations in the prefecture during the period from 1961 to 2010 by using the method of climatological diagnosis. The results show that there was a big difference in mean annual precipitation among the meteorological stations, and the annual precipitation was gradually decreased from the south to the north. The coefficient of variation revealed that there was an increase trend of annual precipitation from the south to the north, and the annual precipitation at all the stations was in a normal distribution. Except at Zeku, there was a decreased trend of annual precipitation in Huangnan Prefecture during the period of 1961-2010, but this trend was not significant. The variation of seasonal precipitation was different from different meteorological stations, but winter precipitation was in an increase trend at all the stations, especially in the south. Analyzed results revealed that a sharp reduction of annual precipitation occurred in the Henan region in 1985, and it occurred possibly around the early 1990s at Jianzha, Tongren, and Zeku meteorological stations. The results also revealed that there was a 10-year periodic change of annual precipitation at these 4 meteorological stations, and 2-4-year, 2-year, 3-5-year and 3-5-year one at Jianzha, Tongren, Zeku, and Henan meteorological stations respectively.

Key words: precipitation, climatological diagnosis, sharp analysis, spatial distribution, Huangnan Prefecture, Qinghai province