This work presents the first lidar observations of a Quasi‐Biennial Oscillation (QBO) in the interannual variations of stratospheric gravity wave potential energy density (E_pm in 30–50 km) at McMurdo (77.84°S, 166.67°E), Antarctica. This paper also reports the first identification of QBO signals in the distance between McMurdo and the polar vortex edge. Midwinter stratospheric gravity wave activity is stronger during the QBO easterly phase when the June polar vortex expands and the polar night jet shifts equatorward. During the QBO westerly phase, gravity wave activity is weaker when the polar vortex contracts and the polar night jet moves poleward. Nine years of lidar data (2011–2019) exhibit the mean E_pm winter maxima being ~43% higher during QBO easterly than westerly. The June polar vortex edge at 45 km altitude moves equatorward/poleward during QBO easterly/westerly phases with ~8° latitude differences (39.7°S vs. 47.7°S) as revealed in 21 years of MERRA‐2 data (1999–2019). We hypothesize that an equatorward shifted polar vortex corresponds to less critical level filtering of gravity waves and thus higher E_pm at McMurdo. The critical level filtering is characterized by wind rotation angle (WRA), and we find a linear correlation between the WRA and E_pm interannual variations. The results suggest that the QBO is likely controlling the interannual variations of the E_pm winter maxima over McMurdo via the critical level filtering. This observationally based study lays the groundwork for a rigorous numerical study that will provide robust statistics to better understand the mechanisms that link the tropical QBO to extratropical waves.

中文翻译：

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通过对南极极涡的调制，准两年一次振荡引起的麦克默多重力波势能密度的年际变化的首次激光雷达观测。

这项工作是南极麦克默多（77.84°S，166.67°E）平流层重力波势能密度（E _pm在30–50 km）年际变化中准双年度振荡（QBO）的首次激光雷达观测。本文还报告了在McMurdo与极地涡旋边缘之间的距离中QBO信号的首次识别。六月初的极地涡旋扩张且极地的夜间喷射向赤道移动时，冬季初的平流层重力波活动在QBO东风期间更强。在QBO西风阶段，当极地涡旋收缩且极地夜流向极移时，重力波活动较弱。激光雷达的九年数据（2011-2019年）显示出平均E _pm在QBO偏东，冬季最大值比西风高约43％。在MERRA-2数据的21年（1999-2019年）中揭示，在45 km高度的6月极地涡旋边缘在QBO东/西风期间向赤道/极向移动，纬度差约为8°（39.7°S与47.7°S）。 。我们假设赤道偏移的极地涡旋对应于重力波的临界级过滤较少，因此在McMurdo处的E _pm较高。临界水平滤波的特征在于风的旋转角度（WRA），我们发现WRA和E _pm年际变化之间存在线性关系。结果表明，QBO可能控制了E _pm的年际变化。通过临界水平过滤，使麦克默多的冬季最大值达到最大值。这项基于观察的研究为进行严格的数值研究奠定了基础，该研究将提供可靠的统计信息，以更好地理解将热带QBO与温带波动联系起来的机制。