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.

中文翻译：

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冬季平流层平流层突然变暖后，南极夏季中层斜向传播季风重力波的影响

重力波（GWs）的斜向传播是指从低纬对流层到极地中间层的纬向传播（或远离其源的垂直传播）。当前的引力波参数化方案中不包括这种传播，但可能是整体动力学结构的重要组成部分。先前的研究表明，季风对流的GW假动量通量（GWMF）与北半球的极地中层云（PMC）的观测值之间具有高度相关性。在这项工作中，我们报告了北半球平流层突然变暖（SSWs）对来自南半球热带的GWs斜向传播的影响的数据和模型分析，这反过来又影响了南半球中层的PMC。为了回应SSW，GWs在中纬度冬季半球的传播得到增强。随着高度的增加，这种增强似乎朝着赤道倾斜，并跟随平流层向东喷射。GWs从南部季风区的倾斜传播往往始于较高的高度，向夏季中层有更尖的极向倾斜构造。夏季南半球PMC与50°N至50°S纬向GWMF之间的相关性表现出一种高相关系数的模式，该模式将冬季平流层与夏季中层层联系起来，表明了半球间耦合机制的影响。温度和风的异常表明，冬季半球的动力学会影响赤道区域，进而影响季风GWs的斜向传播。