The Influence of Obliquely Propagating Monsoon Gravity Waves in the Southern Polar Summer Mesosphere After Stratospheric Sudden Warmings in the Winter Stratosphere
The Influence of Obliquely Propagating Monsoon Gravity Waves in the Southern Polar Summer Mesosphere After Stratospheric Sudden Warmings in the Winter Stratosphere
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DOI：
10.1029/2020jd033970
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发表时间：
2021-02
期刊：
影响因子：
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通讯作者：
D. Alexandre;B. Thurairajah;S. England;C. Cullens
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文献类型：
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作者：
D. Alexandre;B. Thurairajah;S. England;C. Cullens
重力波（GW）的斜向传播是指从低纬度对流层到极地中间层的纬度传播（或远离源的垂直传播）。这种传播不包括在当前的重力波参数化方案中，但可能是全局动力结构的重要组成部分。先前的研究表明，季风对流的引力波赝动量通量（GWMF）观测值与北半球极地中层云（PMC）观测值之间存在高度相关性。在这项工作中，我们报告了北半球平流层突然变暖（SSW）对来自南半球热带地区的GW斜向传播的影响的数据和模型分析，这反过来又影响了南部夏季中间层的PMC。响应南海风暴，中纬度冬半球的巨波传播增强。这种增强似乎随着高度的增加而向赤道倾斜，并跟随平流层向东急流。来自南部季风区的重力波的倾斜传播往往从较高的海拔开始，并具有朝向夏季中间层的更尖锐的极地倾斜结构。夏季南半球PMC与50°N至50°S纬向GWMF之间的相关性呈现出连接冬季平流层和夏季中间层的高相关系数模式，表明半球间耦合机制的影响。温度和风异常表明冬半球的动态可以影响赤道地区，进而影响季风引力波的斜向传播。
Oblique propagation of gravity waves (GWs) refers to the latitudinal propagation (or vertical propagation away from their source) from the low‐latitude troposphere to the polar mesosphere. This propagation is not included in current gravity wave parameterization schemes, but may be an important component of the global dynamical structure. Previous studies have revealed a high correlation between observations of GW pseudomomentum flux (GWMF) from monsoon convection and Polar Mesospheric Clouds (PMCs) in the northern hemisphere. In this work, we report on data and model analysis of the effects of stratospheric sudden warmings (SSWs) in the northern hemisphere, on the oblique propagation of GWs from the southern hemisphere tropics, which in turn influence PMCs in the southern summer mesosphere. In response to SSWs, the propagation of GWs at the midlatitude winter hemisphere is enhanced. This enhancement appears to be slanted toward the equator with increasing altitude and follows the stratospheric eastward jet. The oblique propagation of GWs from the southern monsoon regions tends to start at higher altitudes with a sharper poleward slanted structure toward the summer mesosphere. The correlation between PMCs in the summer southern hemisphere and the zonal GWMF from 50°N to 50°S exhibits a pattern of high‐correlation coefficients that connects the winter stratosphere with the summer mesosphere, indicating the influence of Interhemispheric Coupling mechanism. Temperature and wind anomalies suggest that the dynamics in the winter hemisphere can influence the equatorial region, which in turn, can influence the oblique propagation of monsoon GWs.