安徽省汛期降水时空分布特征

Characteristics of Spatial and Temporal Distribution of Precipitation in Flood Season over Anhui Province

利用安徽省1961--2014年月平均降水资料，通过自然正交分解（EOF）和Moflet小波变换等分析方法分析了安徽省汛期（6—8月）降水的时空分布特征。结果表明，汛期降水量在空间分布上由南向北依次递减，每个站点降水占全年降水的百分比呈现相反的空间分布；EOF前4个模态的累计解释方差贡献率达到80％，第1模态全省基本为负，绝对值大值区主要分布在安徽西南部；第2模态表明东西部降水为相反分布型；第3模态表现为南北多（少）中间少（多）的分布特征；第4模态说明汛期降水东西向大致呈现出“多少多”或“少多少”分布型；汛期降水存在8—10年的周期，贯穿于整个时间序列；还存在6年和2-4年的周期变化，在8—10年的时间域上，安徽汛期降水经历“少到多”的6个循环交替。

Using the monthly mean precipitation data from 1961 to 2014 over Anhui Province, the spatial and temporal distribution characteristics of rainfall in flood season（from June to August） were analyzed through empirical or- thogonal function （EOF）, Morlet wavelet transformation and so on. The results showed that precipitation reduced in turn from South to North on the spatial distribution and the percentage of each sta- tion＇s rainfall in flood season presents the opposite distribution.The cumulative explained variance of EOF first three modes reached 80%. The v.alues of first mode were almost negative over the all province,with high absolute values in the Southwest of Anhui. The second mode indicated that distribution of rainfall in the East and West were contrary.The third mode showed the distribution char- acteristic of greater rainfall in the South and North and less in the central part. The fourth mode of EOF indicated that rainfall in flood season had the distribu- tion form of more, less and more from East to West.There were periodic varia- tion of 6 years,2 to 4 years and 8 to 10 years,which existed throughout the en- tire time series. The rainfall in flood season in Anhui experienced six cycles in the 8 to 10 year time scale.