A tropospheric pathway of the stratospheric quasi-biennial oscillation (QBO) impact on the boreal winter polar vortex

<p>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 kn...

Full description

Bibliographic Details
Main Authors: K. Yamazaki, T. Nakamura, J. Ukita, K. Hoshi
Format: Article
Language:English
Published: Copernicus Publications 2020-04-01
Series:Atmospheric Chemistry and Physics
Online Access:https://www.atmos-chem-phys.net/20/5111/2020/acp-20-5111-2020.pdf
id doaj-ee37fd52145f493584d3f8ba34705569
record_format Article
spelling doaj-ee37fd52145f493584d3f8ba347055692020-11-25T02:38:16ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242020-04-01205111512710.5194/acp-20-5111-2020A tropospheric pathway of the stratospheric quasi-biennial oscillation (QBO) impact on the boreal winter polar vortexK. Yamazaki0K. Yamazaki1T. Nakamura2J. Ukita3K. Hoshi4Faculty of Environmental Earth Science, Hokkaido University, Sapporo, 060-0810, Japannow at: Arctic Research Center, Hokkaido University, Sapporo, 001-0021, JapanFaculty of Environmental Earth Science, Hokkaido University, Sapporo, 060-0810, JapanFaculty of Science, Niigata University, Niigata, 950-2181, JapanGraduate School of Science and Technology, Niigata University, Niigata, 950-2181, Japan<p>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.</p>https://www.atmos-chem-phys.net/20/5111/2020/acp-20-5111-2020.pdf
collection DOAJ
language English
format Article
sources DOAJ
author K. Yamazaki
K. Yamazaki
T. Nakamura
J. Ukita
K. Hoshi
spellingShingle K. Yamazaki
K. Yamazaki
T. Nakamura
J. Ukita
K. Hoshi
A tropospheric pathway of the stratospheric quasi-biennial oscillation (QBO) impact on the boreal winter polar vortex
Atmospheric Chemistry and Physics
author_facet K. Yamazaki
K. Yamazaki
T. Nakamura
J. Ukita
K. Hoshi
author_sort K. Yamazaki
title A tropospheric pathway of the stratospheric quasi-biennial oscillation (QBO) impact on the boreal winter polar vortex
title_short A tropospheric pathway of the stratospheric quasi-biennial oscillation (QBO) impact on the boreal winter polar vortex
title_full A tropospheric pathway of the stratospheric quasi-biennial oscillation (QBO) impact on the boreal winter polar vortex
title_fullStr A tropospheric pathway of the stratospheric quasi-biennial oscillation (QBO) impact on the boreal winter polar vortex
title_full_unstemmed A tropospheric pathway of the stratospheric quasi-biennial oscillation (QBO) impact on the boreal winter polar vortex
title_sort tropospheric pathway of the stratospheric quasi-biennial oscillation (qbo) impact on the boreal winter polar vortex
publisher Copernicus Publications
series Atmospheric Chemistry and Physics
issn 1680-7316
1680-7324
publishDate 2020-04-01
description <p>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.</p>
url https://www.atmos-chem-phys.net/20/5111/2020/acp-20-5111-2020.pdf
work_keys_str_mv AT kyamazaki atroposphericpathwayofthestratosphericquasibiennialoscillationqboimpactontheborealwinterpolarvortex
AT kyamazaki atroposphericpathwayofthestratosphericquasibiennialoscillationqboimpactontheborealwinterpolarvortex
AT tnakamura atroposphericpathwayofthestratosphericquasibiennialoscillationqboimpactontheborealwinterpolarvortex
AT jukita atroposphericpathwayofthestratosphericquasibiennialoscillationqboimpactontheborealwinterpolarvortex
AT khoshi atroposphericpathwayofthestratosphericquasibiennialoscillationqboimpactontheborealwinterpolarvortex
AT kyamazaki troposphericpathwayofthestratosphericquasibiennialoscillationqboimpactontheborealwinterpolarvortex
AT kyamazaki troposphericpathwayofthestratosphericquasibiennialoscillationqboimpactontheborealwinterpolarvortex
AT tnakamura troposphericpathwayofthestratosphericquasibiennialoscillationqboimpactontheborealwinterpolarvortex
AT jukita troposphericpathwayofthestratosphericquasibiennialoscillationqboimpactontheborealwinterpolarvortex
AT khoshi troposphericpathwayofthestratosphericquasibiennialoscillationqboimpactontheborealwinterpolarvortex
_version_ 1724791721920823296