Response of tropical convection over the western Pacific to stratospheric polar vortex during boreal winter,International Journal of Climatology

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Response of tropical convection over the western Pacific to stratospheric polar vortex during boreal winter
International Journal of Climatology ( IF 3.5 ) Pub Date : 2022-09-14 , DOI: 10.1002/joc.7869
Feiyang Wang _{1,

2} , Rui Huang ₃ , Lei Wang ₂

Affiliation

It has been extensively discussed that stratospheric polar vortex significantly contribute to the variability and predictability of tropospheric weather and climate over midlatitudes and polar regions. However, we currently have little understanding of the exact influence of stratospheric polar vortex on tropical troposphere. Here, the exact responses of tropical convection to Northern Hemisphere (NH) extreme stratospheric polar vortex events (i.e., strong vortex [SV] events and weak vortex [WV] events) are investigated in this study. We find that the western Pacific region is particularly noteworthy when focusing on the spatial distribution of tropical convective activity. Significant enhancement of convective activity over the western Pacific is clearly observed in about 2 weeks after WV events, while opposite responses to SV events can also be expected. The change in convective activity over the western Pacific is considerably contributed by the intraseasonal variability, and thus MJO phase 7 (3) is dominant after WV (SV) events. The seesaw pattern of zonal-mean convective activity near equator may be a property of MJO itself, not definitely caused by the stratospheric polar vortex as previously thought. A significantly linear correlation between anomalous convective activity and static stability near tropopause over the western Pacific is found, suggesting that circumstances in the tropical upper troposphere play a crucial role in the evolution of tropical convection, especially for the MJO.

中文翻译：

北半球冬季西太平洋热带对流对平流层极涡的响应

人们已经广泛讨论了平流层极涡对中纬度和极地地区对流层天气和气候的可变性和可预测性的重大贡献。然而，目前我们对平流层极涡对热带对流层的确切影响知之甚少。在这里，本研究调查了热带对流对北半球 (NH) 极端平流层极涡事件（即强涡 [SV] 事件和弱涡 [WV] 事件）的确切响应。我们发现，在关注热带对流活动的空间分布时，西太平洋地区尤其值得注意。在 WV 事件发生后约 2 周内可以清楚地观察到西太平洋上空对流活动的显着增强，同时也可以预期对 SV 事件的相反反应。西太平洋对流活动的变化在很大程度上是由季节内变化引起的，因此 MJO 阶段 7 (3) 在 WV (SV) 事件之后占主导地位。赤道附近纬向平均对流活动的跷跷板模式可能是 MJO 本身的一个特性，而不是像以前认为的那样肯定是由平流层极涡引起的。发现西太平洋对流层顶附近的异常对流活动与静态稳定性之间存在显着的线性相关性，这表明热带对流层上层的环境在热带对流的演变中起着至关重要的作用，特别是对于 MJO。因此，MJO 阶段 7 (3) 在 WV (SV) 事件之后占主导地位。赤道附近纬向平均对流活动的跷跷板模式可能是 MJO 本身的一个特性，而不是像以前认为的那样肯定是由平流层极涡引起的。发现西太平洋对流层顶附近的异常对流活动与静态稳定性之间存在显着的线性相关性，这表明热带对流层上层的环境在热带对流的演变中起着至关重要的作用，特别是对于 MJO。因此，MJO 阶段 7 (3) 在 WV (SV) 事件之后占主导地位。赤道附近纬向平均对流活动的跷跷板模式可能是 MJO 本身的一个特性，而不是像以前认为的那样肯定是由平流层极涡引起的。发现西太平洋对流层顶附近的异常对流活动与静态稳定性之间存在显着的线性相关性，这表明热带对流层上层的环境在热带对流的演变中起着至关重要的作用，特别是对于 MJO。

更新日期：2022-09-14

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