Response of tropical convection over the western Pacific to stratospheric polar vortex during boreal winter
Response of tropical convection over the western Pacific to stratospheric polar vortex during boreal winter
复制标题
DOI：
10.1002/joc.7869
复制
发表时间：
2022-09
期刊：
影响因子：
--
通讯作者：
Feiyang Wang;Rui Huang;Lei Wang
中科院分区：
文献类型：
--
作者：
Feiyang Wang;Rui Huang;Lei Wang
平流层极地涡旋对中纬度和极地对流层天气和气候的变率和可预测性有重要贡献。然而，我们目前对平流层极涡对热带对流层的确切影响知之甚少。本文研究了热带对流对北半球极端平流层极涡事件（即强涡[SV]事件和弱涡[WV]事件）的精确响应。我们发现，在关注热带对流活动的空间分布时，西太平洋地区特别值得注意。西太平洋对流活动明显增强是在西热带气旋事件发生后2周左右，而西太平洋对流活动的相反响应也可能是在西热带气旋事件发生后2周左右。西太平洋对流活动的变化在很大程度上受季节内变率的影响，因此WV （SV）事件后MJO第7(3)期占主导地位。赤道附近纬向平均对流活动的跷跷板模式可能是MJO本身的特性，而不像以前认为的那样肯定是由平流层极地涡旋引起的。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著的线性相关，这表明热带对流层上层的情况对热带对流的演变起着至关重要的作用，特别是对MJO。
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.