Asymmetry of Westerly and Easterly Wind Events: Observational Evidence
Asymmetry of Westerly and Easterly Wind Events: Observational Evidence
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DOI：
10.2151/sola.2016-009
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发表时间：
2016
期刊：
影响因子：
1.9
通讯作者：
Michiya Hayashi;M. Watanabe
中科院分区：
文献类型：
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作者：
Michiya Hayashi;M. Watanabe
西风和东风事件是赤道太平洋上空短时间的异常西风和东风表面风，它们的强度异常大。由于它们的相对发生频率和对背景条件的依赖性尚未完全澄清，我们分析了1982 - 2013年的每日地面风，从中检测到WWE和EWE。这两种类型的事件都出现在太平洋暖池上空，那里的海表温度（SST）足够高，足以形成活跃的深对流，并且随着Niño 4 SST的增加而有利地发生。然而，EWE的出现频率小于WWE，导致风振幅的不对称性。局地异常对流和远距离异常对流在激发这些事件中同样重要，但不同的局地发展过程导致发生频率的不对称性。这些结果也可以在风应力异常中看到，尽管由于其中的非线性而被掩盖。西风和东风事件的不对称性：观测证据。
Westerly (WWEs) and easterly (EWEs) wind events, short- lived anomalous westerly and easterly surface winds, are known to occur with unusual large magnitude over the equatorial Pacific. As their relative frequency of occurrence and dependence on background conditions are yet to be fully clarified, we analyzed daily surface winds for 1982−2013 from which WWEs and EWEs are detected. Both types of events appear over the Pacific warm pool, where sea surface temperature (SST) is sufficiently high for active deep convection, and favorably occur with increasing Niño4 SST. However, the frequency of occurrence of EWEs is less than that of WWEs, resulting in asymmetry in wind amplitude. Local and remote anomalous convections are equally important in exciting these events, but different local development processes cause the asymmetry in the frequency of occurrence. These results can also be seen in wind stress anomalies, albeit obscured due to nonlinearity therein. Asymmetry of westerly and easterly wind events: Observational evidence.