Influence of Enhanced Planetary Wave Activity on the Polar Vortex Enhancement Related to Energetic Electron Precipitation
Influence of Enhanced Planetary Wave Activity on the Polar Vortex Enhancement Related to Energetic Electron Precipitation
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DOI：
10.1029/2019jd032137
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发表时间：
2020-05-16
影响因子：
4.4
通讯作者：
Mursula, Kalevi
中科院分区：
文献类型：
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作者：
Asikainen, Timo;Salminen, Antti;Mursula, Kalevi
北极涡旋经历了相当大的年际变化，这也反映在对流层天气中。最近的研究表明，极地涡旋的变化与近地空间进入极地大气的高能电子降水（EEP）之间存在联系，而高能电子降水是由EEP引起的化学变化介导的，导致中间层和平流层的臭氧损失。极地涡旋最剧烈的变化是由于平流层突然变暖（SSWs）。增强的行星波辐合和经向环流可能引起极涡的短暂破裂。本文利用ERA-40和ERA-Interim联合再分析数据和地磁活动作为EEP的代表，研究了1957-2017年ssw与大气对EEP响应的关系。研究发现，极涡增强和其他相关的动力响应仅在冬季发生南纬风时才会出现，而在南纬风发生之前，南纬风相关的变化较为系统。我们发现，在这些时期，进入平流层的行星波活动系统地增加，从而有利于波-平均流相互作用的增强，这可以动态地放大臭氧损失引起的初始极涡增强。这些结果强调了将行星波活动作为观测极涡旋效应的必要条件的重要性。
The Northern polar vortex experiences considerable interannual variability, which is also reflected to tropospheric weather. Recent research has established a link between polar vortex variations and energetic electron precipitation (EEP) from the near-Earth space into the polar atmosphere, which is mediated by EEP-induced chemical changes causing ozone loss in the mesosphere and stratosphere. The most dramatic changes in the polar vortex are due to sudden stratospheric warmings (SSWs). Enhanced planetary wave convergence and meridional circulation may cause an SSW, a temporary breakdown of the polar vortex. Here we study the relation of SSWs to the atmospheric response to EEP in 1957-2017 using combined ERA-40 and ERA-Interim reanalysis data and geomagnetic activity as a proxy of EEP. We find that the EEP-related enhancement of the polar vortex and other associated dynamical responses are seen only during winters when an SSW occurs and that the EEP-related changes are observed systematically slightly before the SSW onset.We show that during these times, the planetary wave activity into the stratosphere is systematically increased, thus favoring enhanced wave-mean-flow interaction, which can dynamically amplify the initial polar vortex enhancement caused by ozone loss. These results highlight the importance of considering planetary wave activity as a necessary condition for observing the effects of EEP on the polar vortex.