The Anomalies of Spring Rainfall in China and its Relation with Tropical Pacific SST and Eurasian Snow
中国春季降水异常及其与热带太平洋海面温度和欧亚大陆积雪的联系

The spatial and temporal characteristics of spring(March-May) rainfall in China and its relations with the previous winter(December-January) and spring sea surface temperature(SST) over the tropical Pacific Ocean and spring snow over Eurasia are investigated using the observed rainfall dataset for the period 1979-2004.The leading EOF mode of normalized spring rainfall shows the most robust variability in the vast regions from the Yangtze River valley to North China(YRNC),representing the variation of spring rainfall in the middle-latitude eastern China.The anomalies of spring rainfall in eastern China show a meridional dipole mode across the Yangtze River valley.The interannual variability of springtime rainfall is notable and becomes more robust after the late 1980s.The anomalies of springtime rainfall over YRNC are significantly correlated with the SST in the tropical Pacific Ocean during the previous winter and spring.Positive spring rainfall anomalies in YRNC correspond to warmer tropical East Pacific Ocean and colder tropical West Pacific Ocean,and vice versa.Although more rainfall over YRNC is associated with increased snow water equivalent(SWE) in the Chukchi Peninsula and the Tibetan Plateau and reduced SWE in the area from south of Lake Baikal to Northeast China,and this correlation becomes insignificant after subtracting El Nio-South Oscillation(ENSO) effect.Thus,the link between Eurasian snow and springtime rainfall over YRNC is probably a component of the relationship between ENSO and rainfall.