Analysis of Variation Characteristics of Precipitation in Sichuan Basin
Based on the data of monthly mean precipitation recorded at 8 weather stations in Sichuan basin from 1954 to 2010,the characteristics of the change in precipitation were analyzed by precipitation concentration index,linear regressive method,moving average curve,anomaly precent,Kendall rank test method,Morlet wavelet analysis,Mann-Kendall rank statistic method and moving t statistic method.The results indicated that the annual distribution of precipitation was regular in a certain degree with the seasonal changes.The fluctuation of annual and the four seasons precipitation exhibited a tendency of decreasing,precipitation in annual and autunn decreased significantly at 0.05 significant level.The major period was less than 10 years in annual,autumn and winter rainfall.1958 and 1997 were the abrupt precipitation in annual and autumn.The two abrupt of summer precipitation were 1979 and 1997.