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A tropospheric pathway of the stratospheric quasi-biennial oscillation (QBO) impact on the boreal winter polar vortex
| Title: | A tropospheric pathway of the stratospheric quasi-biennial oscillation (QBO) impact on the boreal winter polar vortex |
| Authors: | Yamazaki, Koji Browse this author →KAKEN DB | | Nakamura, Tetsu Browse this author →KAKEN DB | | Ukita, Jinro Browse this author →KAKEN DB | | Hoshi, Kazuhira Browse this author |
| Issue Date: | 30-Apr-2020 |
| Publisher: | European Geosciences Union |
| Journal Title: | Atmospheric Chemistry and Physics |
| Volume: | 20 |
| Issue: | 8 |
| Start Page: | 5111 |
| End Page: | 5127 |
| Publisher DOI: | 10.5194/acp-20-5111-2020 |
| Abstract: | The quasi-biennial oscillation (QBO) is quasi-periodic oscillation of the tropical zonal wind in the stratosphere. When the tropical lower stratospheric wind is easterly (westerly), the winter Northern Hemisphere (NH) stratospheric polar vortex tends to be weak (strong). This relation is known as the Holton–Tan relationship. Several mechanisms for this relationship have been proposed, especially linking the tropics with high latitudes through stratospheric pathway. Although QBO impacts on the troposphere have been extensively discussed, a tropospheric pathway of the Holton–Tan relationship has not been explored previously. Here, we propose a tropospheric pathway of the QBO impact, which may partly account for the Holton–Tan relationship in early winter, especially in the November–December period. The study is based on analyses of observational data and results from a simple linear model and atmospheric general circulation model (AGCM) simulations. The mechanism is summarized as follows: the easterly phase of the QBO is accompanied with colder temperature in the tropical tropopause layer, which enhances convective activity over the tropical western Pacific and suppresses it over the Indian Ocean, thus enhancing the Walker circulation. This convection anomaly generates a Rossby wave train, propagating into the midlatitude troposphere, which constructively interferences with the climatological stationary waves, especially in wavenumber 1, resulting in enhanced upward propagation of the planetary wave and a weakened polar vortex. |
| Type: | article |
| URI: | http://hdl.handle.net/2115/84223 |
| Appears in Collections: | 環境科学院・地球環境科学研究院 (Graduate School of Environmental Science / Faculty of Environmental Earth Science) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)
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Submitter: 山崎 孝治
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