Relationship between Winter Northern Eurasian Fresh Snow Extent and Summer Climate Anomalies in China

Utilizing Version 3 NSIDC weekly snow cover data for the period of 19662005, the relationships between the increased snow cover in winter over Northern Eurasia (TFSE, Total Fresh Snow Extent) and the climate anomalies in summer (JuneAugust) over China are investigated, which show not only the remarkable negative (positive) correlations with precipitation (temperature) in the south of the Yangtze River (SYR), but also the opposite correlations in the northeast of China. The detailed analysis reveals that: following heavy winter TFSE, there are statistically in summer an intensified anomalous low almost in the entire troposphere in the east of Baikal, an enhanced westerly jet in East Asia (EAWJ), and a strengthened subtropical high in the western Pacific (WPSH) which expands westward and northward to the SYR overhead, as well as weakened convection and vapor flux in the SYR. Under these situations, the SYR region tends to be droughty and hot, and the northeast of China tends to be cold, vice versa. The analysis also shows that the correlations between winter TFSE and summer climate anomalies in China are almost independent of ENSO and stable relatively in recent 40 years. But both the winter TFSE and rainfall in the SYR exhibit a remarkable decadal climate shift at the beginning of the 1990s, in which the winter TFSE (summer SYR rainfall) decreases (increases) obviously later than the early 1990s, and simultaneously, the correlation between winter TFSE and summer rainfall in the Huaihe River valley, just north of the Yangtze River, in China is also enhanced. Further analysis explains that winter TFSE could lead to the summer climate anomalies in China by affecting EAWJ.