Interdecadal Change of the Impact of Eurasian Snow on Spring Precipitation Over Southern China

This study investigates the interdecadal changes in the relationship between the Eurasian snow cover extent (SCE) and spring precipitation over southern China. The results show that the spring precipitation over southern China has experienced an obvious change from an active to a quiet period since the late 1980s. The entire data set is divided into two subperiods, that is, 1972-1987 (P1) and 1988-2009 (P2). The interannual variation of the spring precipitation of southern China is found to be significantly related to Eurasian SCE anomalies around northwest of Lake Baikal. Less-than-normal SCE northwest of Lake Baikal corresponds to more-than-normal spring precipitation over southern China. The result of a numerical experiment performed using a baroclinic atmospheric model indicates that the Eurasian snow anomalies around northwest of Lake Baikal can impact the variation of spring precipitation over southern China by modulating the atmospheric circulations over eastern Asia and the western North Pacific region. Further examination shows that the SCE anomalies around Lake Baikal contribute differently to the variation of spring precipitation over southern China before and after the late 1980s. During P1, the SCE anomalies around Lake Baikal contribute to the variation of spring precipitation over China in the form of a mono-sign pattern, which is similar to the first empirical orthogonal function mode of spring precipitation, while in P2, the SCE anomalies around Lake Baikal favor a north-south dipole mode of the spring precipitation variation, which bears considerable similarity to the second empirical orthogonal function mode of spring precipitation over China.