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Gravity Wave Morphology During the 2018 Sudden Stratospheric Warming Simulated by a Whole Neutral Atmosphere General Circulation Model
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  • Shingo Watanabe,
  • Dai Koshin,
  • Shunsuke Noguchi,
  • Kaoru Sato
Shingo Watanabe
Japan Agency for Marine-Earth Science and Technology

Corresponding Author:wnabe@jamstec.go.jp

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Dai Koshin
The University of Tokyo
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Shunsuke Noguchi
Japan Agency for Marine-Earth Science and Technology
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Kaoru Sato
University of Tokyo
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Atmospheric gravity waves (GWs) during the February 2018 sudden stratospheric warming (SSW) were simulated using the T639L340 whole neutral atmosphere general circulation model. Their characteristic morphology around the drastically evolving polar vortex was revealed by three-dimensional (3D) visualization and ray-tracing analyses. The 3D morphology of simulated GWs was described for the three key days that represent the pre-SSW, the mature stage for the vortex splitting, and the late SSW. The combination of strong winds along the polar vortex edge and underneath the tropospheric winds with similar wind directions consisted of the deep waveguide for the upward-propagating GWs, forming GW hot spots in the middle atmosphere. The GW hot spots associated with the development of the SSW were limited to North America and Greenland, and they included the typical upward-propagating orographic GWs with relatively long vertical wavelengths. Different types of characteristic GW signatures were also recognized around the Canadian sub-vortex (CV). The GWs having short vertical wavelengths formed near the surface and obliquely propagated over long distances along the CV winds. The non-orographic GWs with short vertical wavelengths formed in the middle stratosphere through the spontaneous adjustment of flow imbalance around the CV. Those GWs cyclonically ascended into the mesosphere along CV winds.