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- Title
Propagation of gravity waves and its effects on pseudomomentum flux in a sudden stratospheric warming event.
- Authors
In-Sun Song; Changsup Lee; Hye-Yeong Chun; Jeong-Han Kim; Geonhwa Jee; Byeong-Gwon Song; Bacmeister, Julio T.
- Abstract
Effects of realistic propagation of gravity waves (GWs) on distribution of GW pseudomomentum fluxes (Fps) are explored using a global ray-tracing model for the 2009 sudden stratospheric warming (SSW). Four-dimensional (4D) (x-z, t) and two-dimensional (2D) (z, t) results are compared for various parameterized Fps. In ray-tracing equations, refraction due to horizontal wind shear and curvature effects are found important and comparable to one another in magnitude. In the 4D, westward Fps are enhanced in the upper troposphere and northern stratosphere, due to refraction and curvature effects around fluctuating jet flows associated with large-scale waves. In the northern polar upper mesosphere and lower thermosphere, eastward Fps are increased in the 4D. GWs are found to propagate more to the upper atmosphere in the 4D, since horizontal propagation and change in wavenumbers due to refraction and curvature effects can make it more possible that GWs elude critical-level filtering and saturation in the lower atmosphere. GW focusing and ray-tube effects have some impacts on changes in Fps. Focusing effects occur around jet cores, and ray-tube effects appear where the polar stratospheric jets vary substantially in space and time. Increase in the Fps in the northern upper stratosphere and the lower thermosphere begins from the early stage of the SSW evolution, and it is present even after the onset in the 4D. Significantly enhanced Fps in the northern stratosphere are likely related to GWs with small intrinsic group velocity (wave capture), and they would change nonlocally nearby large-scale vortex structure without changing substantially local mean flows.
- Subjects
GRAVITY waves; THEORY of wave motion; UPPER atmosphere; ATMOSPHERIC boundary layer; JETS (Fluid dynamics); ROSSBY waves; MESOSPHERE
- Publication
Atmospheric Chemistry & Physics Discussions, 2020, p1
- ISSN
1680-7367
- Publication type
Article
- DOI
10.5194/acp-2019-1046