华北夏季旱涝的特征分析

Characteristic analysis of unusual summer precipitation in North China

根据华北地区18个代表站1951—2006年月平均降水量资料，对华北地区夏季降水进行了统计分析。采用单站旱涝Z指数变换和区域旱涝指数对华北区域56a的旱涝进行了分析，利用经验正交函数展开、小波分析、M-K突变检验等方法，对华北地区夏季降水时空分布特征进行了研究，并分析了华北夏季降水异常的大气环流特征。结果表明：降水偏多或偏少时段明显，华北夏季降水最主要的空间分布型是全区一致，华北夏季降水量具有准18a、准10a和准2～4a的周期，由多雨阶段转为少雨阶段的突变点为1976年；华北地区夏季旱、涝年份，其对应的高空环流存在显著性差异。

Based on 18 stations＇ monthly rainfall from 1951 to 2006, the summer drought and flood in North China was analyzed by single station z-index and area dry and water-logging index, and the temporal and spatial characteristic of summer precipitation was investigated by EOF natural orthogonal Launch and wavelet analysis methods. The results showed that the period of time for unusual rainfall was obvious, the main spatial distribution style was consistent for the whole North China, and the quasi-periods of summer rainfall of 18, 10 and 2 -4 a existed, and there is an obvious difference of general circulations between summer drought and flood years in north China.