Relationship between stationary planetary wave activity and the East Asian winter monsoon
Relationship between stationary planetary wave activity and the East Asian winter monsoon
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DOI：
10.1029/2004jd005669
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发表时间：
2005-07-30
影响因子：
4.4
通讯作者：
Huang, RH
中科院分区：
文献类型：
--
作者：
Chen, W;Yang, S;Huang, RH
定常行星波活动和东亚冬季风的变率都与海洋和陆地之间的热力差异密切相关。在这项研究中，我们探讨了季风与行星波活动之间的年际关系，行星波活动由500百帕50°N和300百帕40°N处伊莱亚森 - 帕尔姆通量散度差值的指数来定义。研究发现，与行星波活动低的冬季相比，在行星波活动高的冬季，对流层中高层行星波向赤道方向的传播更强。在这些行星波活动高的冬季，从对流层向上传播到平流层的波变得更弱。这伴随着极涡的扰动变小，极涡往往更冷更强。同时，东亚西风急流、东亚大槽、西伯利亚高压和阿留申低压都明显减弱。特别是西伯利亚高压和阿留申低压的减弱降低了东亚上空的东北风，导致该地区尤其是东北亚出现变暖状况。进一步分析表明，行星波的纬向波数 - 2模式对东亚冬季风的变率起主导作用。
The variability of both the stationary planetary wave activity and the East Asian winter monsoon is strongly associated with the thermal contrast between oceans and landmasses. In this study, we explore the interannual relationship between the monsoon and the wave activity defined by an index of the difference in the divergence of Eliassen-Palm flux between 50 degrees N at 500 hPa and 40 degrees N at 300 hPa. It is found that, compared to the winters of low wave activity, the equatorward propagation of planetary waves in the middle and upper troposphere is stronger in the high wave activity winters. During these high activity winters, the upward wave propagation from the troposphere into the stratosphere becomes weaker. This is accompanied by a smaller perturbation in the polar vortex, which tends to be colder and stronger. In the meantime, the East Asian westerly jet stream, the East Asian trough, the Siberian high, and the Aleutian low all become weaker apparently. In particular, the weakening of the Siberian high and the Aleutian low decreases the northeasterly wind over East Asia, leading to a warming condition in the region especially in northeastern Asia. A further analysis reveals that the zonal wavenumber-2 pattern of planetary waves contributes dominantly to the variability of the East Asian winter monsoon.