Liang H.-L.,Yunnan Meteorological Observatory |
Xu Y.-Y.,Yunnan Meteorological Observatory |
Daun W.,Meteorological Science Institute of Yunnan
Journal of Tropical Meteorology | Year: 2013
Recent studies indicated that except for the land-sea thermal contrast, there also existed the land-land thermal contrast. The composite analysis and t-test method are used to further study the local thermal contrast variation over the Asian continent, and to discuss the association of seasonal variation of land thermal state with circulation over East Asia, the early summer and summer monsoon activity, and the precipitation anomaly in China in the decadal scale. Results show that the positive meridional temperature anomaly transports downward from upper tropospheric layers in middle-high latitudes north of 25°N in the positive years. In the zonal direction, the Tibetan Plateau heating in the successive spring acts as a force to influence the atmosphere, leading to the rapid temperature warming over eastern Chinese continent, which could increase the land-sea thermal contrast with the negative SSTA. Accordingly, the monsoon activity in early summer over East Asian establishes earlier and the summer monsoon intensity becomes stronger. The early summer precipitation is more-than-normal over the Yangtze River, and the summer precipitation is more-than-normal over the north China and the southwest China. The situation is contrary in the negative years.