The terraced thermal contrast among the Tibetan Plateau, the East Asian plain, and the western North Pacific and its impacts on the seasonal transition of East Asian climate
The heating sources over the Tibetan Plateau (TP), the East Asian plain, and the western North Pacific (WNP) form a terraced thermal contrast in the west-east direction. Over East Asia and the WNP, this zonal thermal contrast contributes as high as 45 % to the seasonal variance based on the EOF analysis and exerts a significant impact on the seasonal transition of the East Asian climate through the enhancement of the year-round southerly to the southeast of the TP in late March and early April. This effect is investigated in this study using a high-resolution regional atmospheric model by doubling the surface sensible heat flux, respectively, over the TP, the East Asian plain, and the WNP in three sensitivity experiments. Comparisons among the experiments reveal that doubling the surface sensible heat flux over the WNP has little upstream response over East Asia. The increased zonal thermal contrast between the TP and the East Asian plain due to doubled heat flux over the TP would induce anomalous northerly over the region with year-round southerly to the southeast of the TP and weaken its seasonal enhancement. Doubling the surface sensible heat flux over the East Asian plain decreases the zonal thermal contrast and leads to southerly anomaly over the region with year-round southerly to the southeast of the TP and South China, which is favorable for the enhancement of the year-round southerly and its eastward extension.
KeywordsTerraced thermal contrast Year-round southerly Tibetan Plateau East Asian plain Western North Pacific
The authors are grateful to three anonymous reviewers for their constructive comments that helped improve the manuscript. This work was supported by the National Natural Science Foundation of China (40905044 and 41075068), the National Key Technologies R&D Program of China (2012BAC22B03), the Program for Changjiang Scholars and Innovative Research Team in University, and a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions.
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