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Influence of Obliquely Propagating Monsoon Gravity Waves on Southern Polar Summer Mesosphere after Stratospheric Sudden Warmings in Winter Stratosphere
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  • David Alexandre,
  • Brentha Thurairajah,
  • Scott L England,
  • Chihoko Y. Cullens
David Alexandre
Virginia Tech

Corresponding Author:davida49@vt.edu

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Brentha Thurairajah
Virginia Polytechnic Institute and State University
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Scott L England
Virginia Polytechnic Institute and State University
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Chihoko Y. Cullens
University of California, Berkeley
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Abstract

Oblique propagation of gravity waves (GWs) refers to 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 Momentum 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, that in turn influence PMCs in the southern summer mesosphere. In response to SSWs, vertical propagation of GWs from high-latitude winter hemisphere is at mid latitudes and appears more slanted toward the equator with increasing altitude, following the weaker stratospheric eastward jet. The oblique propagation of GWs from southern monsoon regions tends to start at higher altitudes with a sharper poleward slanted structure towards the summer mesosphere. The correlation between PMCs in summer southern hemisphere and the zonal GWMF from 50°N to 50°S exhibits a high-correlation pattern that connects the winter stratosphere with the summer mesosphere, indicating the influence of inter-hemispheric coupling mechanism. Temperature and wind anomalies suggest that the dynamics in winter hemisphere can influence the equatorial region, which in turn, can influence the oblique propagation of monsoon GWs.