Evolution mechanism of the western Pacific subtropical high |
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Authors: | Cao?Jie? author-information" > author-information__contact u-icon-before" > mailto:caojie@sina.com" title=" caojie@sina.com" itemprop=" email" data-track=" click" data-track-action=" Email author" data-track-label=" " >Email author,Huang?Ronghui,Xie?Yingqi,Tao?Yun |
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Affiliation: | 1. Department of Earth Sciences, Science College, Yunnan University, Kunming 650091, China 2. Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China 3. Meteorological Observatory of Yunnan Province, Kunming 650034, China |
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Abstract: | To surmount the deficiency in studying the multiple equilibrium states in the atmosphere motion with highly truncated spectral method, the trigonometric functions for describing the proto-typical 500 hPa height fields and the outgoing long wave radiation (OLR) fields are retrieved re-spectively for the northward bias and the southward bias years of the western Pacific subtropical high with corresponding observational data and the optimum subset retrieval method for four fac-tors. Then the evolution mechanism of the western Pacific subtropical high is studied by means of multiple equilibrium state theory. The results show that the cause of inducing the abnormal location of the western Pacific subtropical high is differences in the early external thermal forcing, which evoke different waveforms in atmosphere. If the early meridional and zonal external thermal forcing differences are stronger, there are wave-mean flow and wave-wave interactions between the response waveforms in atmosphere. In such a case, the western Pacific subtropical high shifts northward obviously. On the contrary, when the early meridional and zonal external thermal forcing differences are weaker, there is no wave-mean flow interaction between the response waveforms in atmosphere, and accordingly the position of the western Pacific subtropical high oscillates with the external thermal forcing oscillation, and is on the south of normal. |
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Keywords: | western Pacific subtropical high wave-mean flow interaction highly truncated spectral method multiple equilibrium state. |
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