Study on Spatial-Temporal Variation Characteristics of Precipitation in Ya'an Area

according to the analysis of monthly accumulated precipitation data of 8 representative stations in Ya'an area from 1951 to 2016,some conclusions was draw as the following:(1) the accumulated precipitation in the central part of Ya'an area is larger,and there are three high value centers,one is near Longcanggou,north of Niba mountain. The second is near Caoke township to the west of Shimian County.The third is near Si Jing,Tianquan County.(2) In the past 60 years,the accumulated precipitation in Ya'an area is mainly decreasing,and the peak value is gradually decreasing;that in Hanyuan county has slightly increased overall.But the peak value of accumulated precipitation has been declining since 1990,showing a decreasing trend in general.(3) The changing period of accumulated precipitation in Ya'an area is alternated,and the accumulated precipitation in all three regions showed an interannual variation of quasi 15~20 years. The oscillation is obvious and constantly changing from low-frequency to high-frequency,and the period of oscillation is getting shorter and shorter. Yucheng District,Yingjing county and Tianquan county had a quasi-5-year cycle before the late 1980 s,while Baoxing county and Shimian county showed a quasi-5-year cycle after the late 1980 s.