利用空间均匀网格对中国夏季降水异常区域特性的初步分析

REGIONAL CHARACTERISTICS OF SUMMER PRECIPITATION ANOMALIES OVER CHINA IDENTIFIED IN A SPATIAL UNIFORM NETWORK

用方差极大正交转动ＥＯＦ（Ｖａｒｉｍａｘ ＥＯＦ）及点相关图法分析了夏季总降水（６、７、８月降水之和）及逐月降水的区域特性。使用的资料为全国范围４７个５°×５°经纬度网格上的降水资料，分析时段为１９５９—１９９４年。分析结果表明，由于采用了空间均匀的格同资料，本分析除进一步证实了中国东部地区降水异常的区域特性外，也揭示了西部地区降水异常的区域特性及沿长江流域东西方向上降水异常的相互关系。夏季总降水异常最显著的区域特性是江淮流域与河套及华南反相关。另外沿长江流域，四川盆地的降水异常与青藏高原东部及江淮流域的降水异常也存在着反相关联系。西部地区的区域特性为青藏高原中东部南北两侧为负相关，并且青藏高原中东部南侧的降水异常与华北东部及东北南部为正相关。上述的空间模都有准２—３ａ及１０ａ左右的周期。逐月降水的分析表明，６月份，江淮流域、华北东部及东北大部分地区为正相关。７月，河套地区与江淮流域的降水异常呈现一定的负相关联系，８月份降水异常的区域特性与夏季总降水异常的区域特性极其一致。

he regional characteristic of precipitation anomalies of total summer precipitation(total precipitation of Jule July and Aug. ) and monthly precipitation are analyzed by using the results of Varimax EOF and correlation analysis. The data set used is the gridpoint precipitation over a(5°lat ×5°lon) network in China in the period of 1954 to 1994.The analysis of total precipitation shows that the most significant regional characteristicis the existence of negative correlation in precipitation anomalies between the low-reaches of Yangtse River and the Huaihe River valley (LRYH region) and the middle-reachesof the Yollow River valley(MRY region), and between the LRYH region and SouthChina. The precipitation anomaly over the Sichuan Basin is negatively correlated withthat over eastern part of Qinghai Xizang Plateau and that over the LRYH region. Theregional characteristics of summer precipitation anomalies in the western China is thatthere exists negative correlation between the summer precipitation anomalies over thesourthern part of the central and eastern Qinghai Xizang Plateau and that over its northern part. There also exists positive correlation between the sourthern part of easternQinghai Xizang Plateau and the eastern part of North China and the southern part ofNortheast China. The above spatial correlation modes have significant periods of about 3years and 10 years. The analyses of the monthly precipitation show that, in Jule, thereexists positive correlation among the precipitation anomalies over the LRYH region, theeastern part of North China and the Northeast China. In July, the precipitation in theMRY region and the LRYH regions are negatively correlated. The regional characteristicss of precipitation anomalies in Aug. is very similar to that of the total summer precipitation anomalies.