Propagation of gravity waves and its effects on pseudomomentum flux in a sudden stratospheric warming event

In Sun Song, Changsup Lee, Hye Yeong Chun, Jeong Han Kim, Geonhwa Jee, Byeong Gwon Song, Julio T. Bacmeister

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Abstract

Effects of realistic propagation of gravity waves (GWs) on distribution of GW pseudomomentum fluxes are explored using a global ray-tracing model for the 2009 sudden stratospheric warming (SSW) event. Four-dimensional (4D; x-z and t) and two-dimensional (2D; z and t) results are compared for various parameterized pseudomomentum fluxes. 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 pseudomomentum fluxes are enhanced in the upper troposphere and northern stratosphere due to refraction and curvature effects around fluctuating jet flows. In the northern polar upper mesosphere and lower thermosphere, eastward pseudomomentum fluxes are increased in the 4D. GWs are found to propagate more to the upper atmosphere in the 4D, since horizontal propagation and change in wave numbers 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 effects occur around jet cores, and ray-tube effects appear where the polar stratospheric jets vary substantially in space and time. Enhancement of the structure of zonal wave number 2 in pseudomomentum fluxes in the middle stratosphere begins from the early stage of the SSW evolution. An increase in pseudomomentum fluxes in the upper atmosphere is present even after the onset in the 4D. Significantly enhanced pseudomomentum fluxes, when the polar vortex is disturbed, are related to GWs with small intrinsic group velocity (wave capture), and they would change nonlocally nearby large-scale vortex structures without substantially changing local mean flows.

Original languageEnglish
Pages (from-to)7617-7644
Number of pages28
JournalAtmospheric Chemistry and Physics
Volume20
Issue number12
DOIs
Publication statusPublished - 2020 Jul 1

Bibliographical note

Funding Information:
This research has been supported by the Korea Polar Research Institute (grant nos. PE19020 and PE20100), the National Meteorological Satellite Center of the Korea Meteorological Administration (grant no. NMSC-2016-3137), and the National Research Foundation of Korea (NRF) funded by the Korea government (MSIT) (grant no. 2017R1A2B2008025).

Funding Information:
Acknowledgements. The authors thank the three anonymous reviewers and the editor for their careful reading of the paper. Their comments substantially improved the original paper. This study was supported by the research funds (grant nos. PE19020 and PE20100) from the Korea Polar Research Institute and funded by the Korea Meteorological Administration/National Meteorological Satellite Center (KMA/NMSCs) project (grant no. NMSC-2016-3137). Also, this work was supported by the National Institute of Supercomputing and Network/Korea Institute of Science and Technology Information with supercomputing resources, including technical support (grant no. KSC-2016-C2-0034). Hye-Yeong Chun was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT; grant no. 2017R1A2B2008025).

Funding Information:
Financial support. This research has been supported by the Korea Polar Research Institute (grant nos. PE19020 and PE20100), the National Meteorological Satellite Center of the Korea Meteorological Administration (grant no. NMSC-2016-3137), and the National Research Foundation of Korea (NRF) funded by the Korea government (MSIT) (grant no. 2017R1A2B2008025).

Publisher Copyright:
© Author(s) 2020.

All Science Journal Classification (ASJC) codes

  • Atmospheric Science

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