The Decadal Shift of the Summer Climate in the Late 1980s over Eastern China and Its Possible Causes

In this paper, it is pointed out that a notable decadal shift of the summer climate in eastern China occurred in the late 1980s. In association with this decadal climate shift, after the late 1980s more precipita-tion appeared in the southern region of eastern China (namely South China), the western Pacific subtropical high stretched farther westward with a larger south-north extent, and a strengthened anticyclone at 850 hPa appeared in the northwestern Pacific. The decadal climate shift of the summer precipitation in South China was accompanied with decadal changes of the Eurasian snow cover in boreal spring and sea surface temperature (SST) in western North Pacific in boreal summer in the late 1980s. After the late 1980s, the spring Eurasian snow cover apparently became less and the summer SST in western North Pacific increased obviously, which were well correlated with the increase of the South China precipitation. The physical pro-cesses are also investigated on how the summer precipitation in China was affected by the spring Eurasian snow cover and summer SST in western North Pacific. The change of the spring Eurasian snow cover could excite a wave-train in higher latitudes, which lasted from spring to summer. Because of the wave-train, an abnormal high appeared over North China and a weak depression over South China, leading to more precip-itation in South China. The increase of the summer SST in the western North Pacific reduced the land-sea thermal contrast and thus weakened the East Asian summer monsoon, also leading to more precipitation in South China.