Interdecadal variation of spring snow depth over the Tibetan Plateau and its influence on summer rainfall over East China in the recent 30 years

Abstract

Previous studies found that spring (March–April) snow depth over the Tibetan Plateau (TP) had increased since the mid-1970s. This study shows that the spring snow depth over the TP decreased after 2002. Meanwhile, atmospheric heating source <Q1> over TP also experienced interdecadal variations from cold to warm phase after the year 2002, which could be linked to the decreasing of the spring snow depth over the TP. Possible physical mechanisms of the influence of the spring snow depth on the atmospheric heat source <Q1> over the TP are explored. A significant positive correlation was found between the spring <Q1> over the TP and subsequent summer (June–August) 500 hPa geopotential height over the western Pacific subtropical high (WPSH) location. The interdecadal shift northward of WPSH and interdecadal variations of the large scale precipitation conditions favoured the increase of summer precipitation to the Huaihe River valley (30°–35°N, 110°–120°E) during 2002–2010 in comparison to 1979–2001.