Linkage between Spring Eurasian Snowmelt and East Asian Summer Monsoon

The effects of spring Eurasian snowmelt on the East Asian summer monsoon (EASM) and summer precipitation in China, in addition to a possibly related physical mechanism, were investigated by using observation data. The leading mode of spring Eurasian snowmelt showed decadal variation, which has good agreement with the EASM interdecadal transition and Chinese summer rainfall. In addition, the second mode of the snowmelt variability correlates positively to EASM variability. When the snowmelt in East Siberia near Balkhash Lake increases in the spring, the EASM tends to appear in a negative-positive-negative meridional wave train structure from high to low latitudes in the summer. When snowmelt decreases, opposite conditions appear. The link mechanism of the spring snowmelt and summer atmospheric circulation in East Asia may be attributed to positive feedback between abnormal snow and atom- spheric thickness anomalies in the same regions during the same period, which promotes two high-pressure systems. Subsequently, the Balkhash Lake high-pressure system develops eastward, and part of the East Siberian high pressure system moves to lower latitudes. As a result, atmospheric circulations in East Asia may form the meridional wave train structure in the summer, which may lead to an anomalous change in the East Asian summer weather and climate.