Precipitation Sequence Trend Analysis of Songhua River Basin in Recent 50 Years

The seasonal variation characteristic of monthly precipitation for Harbin Hydrological Station in Songhua River is analyzed using the precipitation observation data from 1961 to 2008 based on the linear regression analysis method and cumulative anomalies method.The results show that the precipitation in summer and autumn presents decreasing tendency as the time change in the Songhua River basin,however,the precipitation in spring and autumn is an opposite tendency.The precipitation change trend in spring is similar to that in winter,which has a less change.And the summer precipitation,the autumn precipitation and the average annual precipitation all show a big fluctuation.