中国东南部地区4-6月强降水的低频变化特征

利用全国2 400多台站逐日降水资料,分析了中国东南部地区4—6月10~30 d低频强降水的时空变化特征。结果表明:4—6月10~30 d低频强降水的方差大值区在中国的长江及其以南地区,中心位于江南的中东部,东南部地区4—6月10~30 d低频强降水距平的第一模态反映该区域呈一致变化。功率谱分析表明第一模态时间变化的周期以10~30 d低频分量为主。根据区域强降水及其10~30 d低频强降水、区域强降水正交经验函数(EOF)分析的第一模态时间系数(PC1)及PC1的10~30 d低频分量的年际方差,结合它们两两之间逐年的相关系数,确定了区域强降水10~30 d强振荡典型年份。对典型年降水异常分布的方差分析,表明强振荡年区域总降水量异常主要是由10~30 d强降水的低频变化引起的。

Low frequency variation characteristics of heavy rainfall over southeastern China from April to June

The spatial and temporal variation characteristics of filtered 10-30 d component for heavy rainfall from April to June over southeastern China are studied by using the daily rainfall station data in China. Results show that the high variance areas of filtered 10-30 d component for heavy rainfall from April to June are in the Yangtze River and South China, and its center is located in the middle-eastern South China. The first mode of filtered 10-30 d component for heavy rainfall from April to June over Southeast China reflects a consistent variation in the region. Power spectrum analysis shows the main period of the first mode is 10-30 d component. Based on the heavy rainfall and filtered 10-30 d component for rainfall, the first Empirical Orthogonal Function(EOF) time series(PC1) of the heavy rainfall and interannual variance of filtered 10-30 d component for PC1, the strong typical years of filtered 10-30 d component for heavy rainfall are revealed in combination with their yearly correlation coefficients between each other. The variance analysis of anomaly spatial distribution in typical years reflects that the anomaly variability of rainfall is mainly due to the variation of the filtered 10-30 d component for rainfall in the region.