Effect of Energy and Water Circulation over Tibetan Plateau

Subjects: Other Disciplines >> Synthetic discipline submitted time 2023-03-28 Cooperative journals: 《中国科学院院刊》

徐祥德 马耀明 孙婵 魏凤英

Abstract： The total amount of radiation over the Tibetan Plateau (TP) is the largest in the world with an extreme area of super solar constant, where a huge heat source “embedded” in the middle troposphere forms a hollow heat island with the effect exceeding any urban agglomerations in the world and an inestimable driving impact on global and regional changes in atmospheric circulation system. In closely association with the seasonal variations of TP’s thermal forcing, the Asian summer monsoon is the most widely in the world with the strongest monsoon intensity. The seasonal changes of solar radiation results in a “rapid response” of sensible heat and its dynamic movement over the TP’s large terrain. The advancing cold-rainfall belts of East Asian summer monsoon stop just along the mountain-plain boundary area in China’s three ladder terrain distribution, indicating that the TP may play key role in summer monsoon process of air-sea-land interactions. The extreme regions of low cloud cover and total cloud cover over China, the sources of large rivers (Yangtze River, Lancang River, Yarlung Zangbo River, etc.) in the TP and the group of lakes and rivers in central-eastern China are spatially almost consistent, reflecting that an inseparable connection of the formation of “Asian Water Tower” and the unique cloud precipitation structure in the TP. The studies revealed that a significant influence of the TP’s atmospheric heat source on the cloudprecipitation and water vapor transport pattern in local and downstream areas. The precipitation in the Yangtze River Reaches has an obvious zonal high correlation structure with the low cloud cover over China, the precipitation in the Yangtze River Reaches has an important relation with the thermal divers of upper TP’s Asian Water Tower, and convection system. From the perspective of acrossequatorial circulations, it is found that the summertime cross-equatorial lower south and upper-north flows between the northern to southern hemispheric atmosphere appears just in the Asian and the North American regions with the TP and the Rocky Mountains. The TP’s zonal and meridional circulation structure and the relevant mechanism of regional and global atmospheric circulation confirm the thermal role of the TP’s “roof of the world” and the convection activities in global energy and water circles. The three-dimensional distribution of special water vapor on the TP and the vertical circulation of atmosphere across the hemispheres show that the TP contributes significantly to the change of global atmospheric circulation. A global Water Tower concept in the TP’s atmosphere was put forward, and it is believed that the “water supply” and “water storage” system of TP’s water tower is built with the “water storage tank” system of the plateau surface glaciers, snow cover and lakes, as well as “water supply pipelines” of rivers transporting water from the water tower to the downstream areas, and the upper atmosphere also provides the channels for outward transport of water vapor from the TP. The TP’s special atmospheric water circulation across the hemisphere can establish “water tower of the world” and its surrounding areas the unique hydrological function, which could provide a comprehensive description of physical picture about the TP’s “water tower of the world” and the land-sea-air water vapor circulation in global scale.

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