Decadal Change in the Correlation Pattern between the Tibetan Plateau Winter Snow and the East Asian Summer Precipitation during 1979–2011

Observational evidence indicates that the correlation between Tibetan Plateau (TP) winter snow and East Asian (EA) summer precipitation changed in the late 1990s. During the period 1979–99, the positive correlation between the TP winter snow and the summer precipitation along the Yangtze River valley (YRV) and southern Japan was disrupted by the decadal climate shift. In contrast, the summer precipitation over the Huaihe River valley (HRV) and the Korean Peninsula showed a strong positive correlation with the preceding winter snow over the TP during the period 2000–11. The radiosonde temperature measurements over the TP show a pronounced warming since the late 1990s. This warming is associated with the significant increase in surface sensible heat flux and longwave radiation into atmosphere. The latter is closely related to the decrease of surface albedo and the soil hydrological effect of melting snow due to the decadal decrease in the preceding winter and spring snow over the TP. The TP warming induced by the decrease in winter snow, together with the cooling of the sea surface temperature in the tropical central and eastern Pacific, intensifies the land–sea thermal contrast in the subsequent spring and summer over EA, thus causing a northward advance of the EA summer monsoon. Accompanying the northward migration of the summer monsoon, the summer precipitation belt over EA shifts northward. Consequently, the high summer precipitation region over EA correlating with the preceding winter snow over the TP has shifted northward from the YRV and southern Japan to the HRV and the Korean Peninsula since the late 1990s.