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...
Main Authors: | , , , |
---|---|
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 |