The interdecadal linkage of the summer precipitation in eastern China with the surface air temperature over Lake Baikal in the past 50 years

The recent change of global surface air temperature indicates that the land regions have warmed at a faster rate than the oceans, and the warming rate is bigger in higher latitudes than the lower latitudes. The warming centers are mainly located in North Asia, Europe, and North America regions over the past 50 years. Thus, the warming in higher latitudes over land possibly affects China climate by modulating the East Asian monsoon circulations. Many studies have explored the longterm trend of the summer precipitation in China, but they mainly focused on the decadal variations of East Asian Summer Monsoon (EASM), the surface thermal anomalies over the Tibetan Plateau (TP), Arctic Oscillation (AO) and the ENSO, but less attention has been paid to the possible impact of land surface air temperature (SAT). In present study, on the basis of the monthly land surface air temperature of Goddard Institute for Space Studies (GISS), the NCEP/NCAR monthly mean reanalysis data, as well as the 604 stationobserved monthly mean temperature and precipitation datasets in China, we discussed the decadal linkage of summer precipitation anomalies in eastern China with the land surface air temperature changes in the Northern Hemisphere during 1951-2007. The results suggest that the summer precipitation appears a meridional seesaw spatial pattern in eastern China before 1996, and it has shifted from the “flooding in north and drought in south” pattern to the “flooding in south and drought in north” mode since the late 1970s. However, our evidences show that the summer precipitation anomalies both in northern China and in the lowermiddle reaches of the Yangtze River have jointly appeared a decreasing trend after 1996, and the recent global warming has destroyed the previous summer precipitation anomalous pattern. It is found that the precipitation in north China bears a significantly negative correlation with the SAT near Lake Baikal on the decadal time scale, where the persistent warming over the past decades can generate an anomalous warmer anticyclone over Mongolian area and weaken the activities of Mongolian cyclone in the troposphere, and then reduce the summer precipitation in north China. Our analysis suggests that the SAT near Lake Baikal has again enhanced after 1996, and it results in a further decrease of the precipitation in north China. Past studies have suggested that Lake Baikal is one of the most obvious regions in the contex of global warming, implying that the global warming may affect the regional climate in China via the SAT changes in North Asia. However, the 10year running correlation coefficients show that the close relationship between the SAT around Lake Baikal and the summer precipitation in China is mostly significant after 1990s, suggesting that the possible mechanism, such as the warming sea surface temperature (SST) in tropical Indian ocean and the cooling trend in the northwestern Pacific ocean, may be also one of the important factors to affect the longterm trend of the summer precipitation in China as proposed by the previous studies. 