Relationships among the monsoon-like southwest Australian circulation, the Southern Annular Mode, and winter rainfall over southwest Western Australia
Relationships among the monsoon-like southwest Australian circulation, the Southern Annular Mode, and winter rainfall over southwest Western Australia
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DOI：
10.1007/s00376-014-4142-z
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发表时间：
2015-06
影响因子：
5.8
通讯作者：
Juan Feng;Jianping Li;Yun Li;Jia Zhu;F. Xie
中科院分区：
文献类型：
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作者：
Juan Feng;Jianping Li;Yun Li;Jia Zhu;F. Xie
本研究根据观测到的降雨量、再分析数据集和数值模拟结果，研究了类季风澳大利亚西南环流（SWAC）、南部环形模态（SAM）和西澳大利亚西南部冬季降雨（SWR）之间的关系。通过使用线性模型将 SWAC 分解为两个分量，即与 SAM 相关的分量 (RSAM) 和与 SAM 无关的分量 (SWACI*)，我们发现 SWACI* 对 SWR 显示出显着影响。同样，与 SWAC 相关的 SAM 组件会对 SWR 产生影响，而与 SAM 无关的组件则对 SWR 产生影响。在与 SWAC 和 SAM 相关的循环方面也得到了类似的结果。这些事实表明 SAM 在影响 SWR 方面发挥着间接作用，并提出了 SWAC 充当 SAM 和 SWR 之间桥梁的可能性，通过 SAM 将其影响传递给 SWR。这是因为 SWAC 的变化与南印度洋和澳大利亚西南部的陆地和海洋之间的热力对比密切相关。相比之下，SAM 与这种热结构没有显着相关，特别是对于与 SWAC 无关的组件。南印度洋表面海水温度的变化有助于形成有利的降雨环流模式。这一发现得到了数值模拟结果的支持。 SWAC和SWR之间的强耦合可能有助于理解SWR和南印度洋之间的相互作用，并为研究SWR的变化提供了另一个视角。
This study examines the relationships among the monsoon-like southwest Australian circulation (SWAC), the Southern Annular Mode (SAM), and southwest Western Australia winter rainfall (SWR), based on observed rainfall, reanalysis datasets, and the results of numerical modeling. By decomposing the SWAC into two components using a linear model, i.e. the component related to SAM (RSAM) and the component unrelated to SAM (SWACI*), we find it is the SWACI* that shows a significant influence on SWR. Similarly, it is the component of SAM associated with SWAC that exhibits an impact on SWR, whereas the component unrelated to SAM. A similar result is obtained in terms of the circulation associated with SWAC and the SAM. These facts suggest the SAM plays an indirect role in influencing SWR, and raise the possibility that SWAC acts as a bridge between the SAM and SWR, by which the SAM passes its influences onto SWR. This is due to the fact that the variations of SWAC are closely linked to the thermal contrast between land and sea across the southern Indian Ocean and southwest Australia. By contrast, the SAM does not significantly relate to this thermal structure, particularly for the component unrelated to SWAC. The variations of surface sea temperature over the southern Indian Ocean contribute to the favored rainfall circulation patterns. This finding is supported by the numerical modeling results. The strong coupling between SWAC and SWR may be instrumental for understanding the interactions between SWR and the southern Indian Ocean, and provides another perspective in examining the variations in SWR.