Analysis of Precipitation Characteristics Variation in Zhejiang Province in the Past 50 Years

Based on the daily precipitation data from 17 stations in Zhejiang Province and combined with the statistics methods,the precipitation characteristics in the period of flood season,dry season and whole year are analyzed.In flood season,the amounts of precipitation have mainly increased in the northeastern and decreased in the southwestern parts of Zhejiang Province.The frequency of precipitation has not decreased significantly while the intensity and the amount of precipitation show a similar tendency in the flood season in the past 50 years.In dry season,the amounts of precipitation have increased significantly.And the intensities of precipitation reduce in the east of Zhejiang while increase in the southern,western and northern parts of the province.The amounts of annual precipitation in the western and northern parts show a trend to increase with 11-year and 21-year periodic changes.There is a decreasing trend after 1980 with 20-year and 8-year periodic changes in the southern part while there shows an increasing trend before 1986 with 11-year,8-year and 21-year periodic changes in the eastern part.