海表温度和地表温度与中国东部夏季异常降水

主要研究太平洋与印度洋海表温度和地表温度场与中国东部夏季降水的相关关系,以及异常大降水产生的下垫面条件.研究结果表明:(1)夏季黑潮区海温与同期长江流域的降水存在明显正相关,北方地区夏季降水与靠近非洲东岸的印度洋海域存在明显负相关.(2)夏季海温异常与同期中国降水异常场之间的相关分析(SVDI)表明,20世纪70年代后期当海温由La Nina多发期向El Nino多发期转变后,长江流域向异常多雨转变,而其北方和南方地区则向异常少雨方向发展.(3)中国东部区域降水与陆面温度的明显相关区有:(a)春,夏季热带非洲和夏季亚洲大陆部分地区地表温度与当年长江流域夏季降水存在显著正相关;(b)春季4、5月份部分亚洲大陆地表温度与当年华北地区夏季降水有明显负相关.(4)通过对比分析发现:长江(1954,1998和1999年)或江淮(1991年)流域几次特大异常降水的下垫面条件是黑潮区为海温正距平,同期欧亚大陆主要为正地表温度距平场.

Sea Surface Temperature, Land Surface Temperature and the Summer Rainfall Anomalies over Eastern China

The correlations between the sea surface temperature (SST) of the Pacific and Indian Oceans and the global land surface temperature (LST) and the summer rainfall over the eastern China respectively are studied in this paper. Results show: (1) The positive correlation between the SST of Kuroshio area and the summer rainfall over the Yangtze River valley is apparent. There are obvious negative correlation between the summer rainfall over North China and the SST of Indian Ocean near Fast Africa coast. (2) The relationship between the variances of the summer rainfall over China and the global SST is also investigated by the singular value decomposition (SVD) analysis. There is an apparent trend with a regime shift (SVDI) of overall anomalies in the late 1970s in both SST and rainfall variations. It is evolved from negative to positive rainfall anomalies over the Yangtze River valley, and opposite to its north and south, when SST was developed from dominated by La Nina events to dominated by El Nino events. (3) There are the obvious correlation regions between the regional rainfall of the eastern China and LST. a) The evident positive correlations between the summer rainfall over the Yangtze River valley and LST cover the tropic Africa in spring and summer, and the partial Asian continent in summer. b) The clear negative correlation between the summer rainfall over the northern China and the partial Asian LST is showed in April and May. (4) The findings by comparison, contrast and analysis are that the common underlying surface conditions of the anomalously heavy rainfall over the Yangtze River valley (1954, 1998 and 1999) or the Changjiang-Huaihe (1991) valley are the positive departure of SST in the Kuroshio area and the mostly positive anomaly of LST over Eurasia.