An unusual sudden stratospheric warming (SSW) event occurred in the Southern Hemisphere in September 2019. Ground-based and satellite observations show the presence of transient eastward- and westward-propagating quasi-10 day planetary waves (Q10DWs) during the SSW. The planetary wave activity maximizes in the mesosphere and lower thermosphere region approximately 10 days after the SSW onset. Analysis indicates that the westward-propagating Q10DW with zonal wave number s = 1 is mainly symmetric about the equator, which is contrary to theory which predicts the presence of an antisymmetric normal mode for such planetary wave. Observations from microwave limb sounder and sounding of the atmosphere using broadband emission radiometry are combined with meteor radar wind measurements from Antarctica, providing a comprehensive view of Q10DW wave activity in the Southern Hemisphere during this SSW. Analysis suggests that the Q10DWs of various wavenumbers are potentially excited from nonlinear wave-wave interactions that also involve stationary planetary waves with s = 1 and s = 2. The Q10DWs are also found to couple the ionosphere with the neutral atmosphere. The timing of the quasi-10-day oscillations (Q10DOs) in the ionosphere are contemporaneous with the Q10DWs in the neutral atmosphere during a period of relatively low solar and geomagnetic activity, suggesting that the Q10DWs play a key role in driving the ionospheric Q10DOs during the Southern SSW event. This study provides observational evidence for coupling between the neutral atmosphere and ionosphere through the upward propagation of global scale planetary waves.

中文翻译：

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2019 年南半球平流层突然变暖期间异常的准 10 天行星波活动和电离层响应

2019 年 9 月，南半球发生了一次异常突然的平流层变暖 (SSW) 事件。 地面和卫星观测显示，在 SSW 期间存在向东和向西传播的准 10 天行星波 (Q10DW)。在 SSW 开始后大约 10 天，行星波活动在中间层和低热层区域达到最大。分析表明，纬向波数为s的向西传播的Q10DW = 1 主要关于赤道对称，这与预测这种行星波存在反对称法向模式的理论相反。微波临边探空仪的观测和使用宽带发射辐射测量的大气探测与南极洲的流星雷达风测量相结合，提供了本次 SSW 期间南半球 Q10DW 波活动的综合视图。分析表明，各种波数的 Q10DWs 可能受到非线性波波相互作用的激发，这些相互作用还涉及s  = 1 和s 的静止行星波 = 2. 还发现 Q10DW 将电离层与中性大气耦合。在太阳和地磁活动相对较低的时期，电离层中准 10 天振荡 (Q10DOs) 的时间与中性大气中的 Q10DWs 是同时期的，这表明 Q10DWs 在驱动电离层 Q10DOs 中起着关键作用南部 SSW 事件。这项研究为中性大气和电离层通过全球尺度行星波的向上传播之间的耦合提供了观测证据。