Some effects of meridional shear and spherical geometry on long stratospheric waves
Abstract Forced, low‐wavenumber disturbances of normal‐mode form are determined for zonal flows with meridional shear, but no vertical shear, using the linearized primitive equations with spherical geometry. Results are presented both for stationary waves in the winter westerlies and for travelling,...
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crwiley:10.1002/qj.49710444105 2024-06-02T08:13:30+00:00 Some effects of meridional shear and spherical geometry on long stratospheric waves Simmons, A. J. 1978 http://dx.doi.org/10.1002/qj.49710444105 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fqj.49710444105 https://rmets.onlinelibrary.wiley.com/doi/pdf/10.1002/qj.49710444105 en eng Wiley http://onlinelibrary.wiley.com/termsAndConditions#vor Quarterly Journal of the Royal Meteorological Society volume 104, issue 441, page 595-614 ISSN 0035-9009 1477-870X journal-article 1978 crwiley https://doi.org/10.1002/qj.49710444105 2024-05-03T11:43:58Z Abstract Forced, low‐wavenumber disturbances of normal‐mode form are determined for zonal flows with meridional shear, but no vertical shear, using the linearized primitive equations with spherical geometry. Results are presented both for stationary waves in the winter westerlies and for travelling, equatorially trapped modes. For flow profiles representative of the winter lower stratosphere results are in agreement with some earlier studies, curvature effects giving a maximum geopotential perturbation close to the axis of the polar night jet. Wave structure is more variable for upper stratospheric profiles of larger meridional scale, and more sensitive to zonal wavenumber, spherical geometry and ageostrophy. Geopotential maxima are typically located polewards of mean flow maxima, and meridional structures are in general agreement with observation. The vertical penetration of disturbances to these broader flows is significantly reduced by singular‐line absorption. Equatorial wave solutions show the vertical wavelength of the Rossby–gravity wave to be sensitive to the meridional scale of the mean flow, and for and asymmetric jet the wave structure is approximately symmetric about the latitude of zero zonal mean absolute vorticity. The Kelvin wave is much less sensitive to meridional shear. A simple expression is given for the zonal mean acceleration due to waves dissipated by Newtonian cooling, and results confirm a suggestion that asymmetries in the zonal mean flow profile will be enhanced by the presence of such waves. Article in Journal/Newspaper polar night Wiley Online Library Quarterly Journal of the Royal Meteorological Society 104 441 595 614 |
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Open Polar |
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Wiley Online Library |
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crwiley |
language |
English |
description |
Abstract Forced, low‐wavenumber disturbances of normal‐mode form are determined for zonal flows with meridional shear, but no vertical shear, using the linearized primitive equations with spherical geometry. Results are presented both for stationary waves in the winter westerlies and for travelling, equatorially trapped modes. For flow profiles representative of the winter lower stratosphere results are in agreement with some earlier studies, curvature effects giving a maximum geopotential perturbation close to the axis of the polar night jet. Wave structure is more variable for upper stratospheric profiles of larger meridional scale, and more sensitive to zonal wavenumber, spherical geometry and ageostrophy. Geopotential maxima are typically located polewards of mean flow maxima, and meridional structures are in general agreement with observation. The vertical penetration of disturbances to these broader flows is significantly reduced by singular‐line absorption. Equatorial wave solutions show the vertical wavelength of the Rossby–gravity wave to be sensitive to the meridional scale of the mean flow, and for and asymmetric jet the wave structure is approximately symmetric about the latitude of zero zonal mean absolute vorticity. The Kelvin wave is much less sensitive to meridional shear. A simple expression is given for the zonal mean acceleration due to waves dissipated by Newtonian cooling, and results confirm a suggestion that asymmetries in the zonal mean flow profile will be enhanced by the presence of such waves. |
format |
Article in Journal/Newspaper |
author |
Simmons, A. J. |
spellingShingle |
Simmons, A. J. Some effects of meridional shear and spherical geometry on long stratospheric waves |
author_facet |
Simmons, A. J. |
author_sort |
Simmons, A. J. |
title |
Some effects of meridional shear and spherical geometry on long stratospheric waves |
title_short |
Some effects of meridional shear and spherical geometry on long stratospheric waves |
title_full |
Some effects of meridional shear and spherical geometry on long stratospheric waves |
title_fullStr |
Some effects of meridional shear and spherical geometry on long stratospheric waves |
title_full_unstemmed |
Some effects of meridional shear and spherical geometry on long stratospheric waves |
title_sort |
some effects of meridional shear and spherical geometry on long stratospheric waves |
publisher |
Wiley |
publishDate |
1978 |
url |
http://dx.doi.org/10.1002/qj.49710444105 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fqj.49710444105 https://rmets.onlinelibrary.wiley.com/doi/pdf/10.1002/qj.49710444105 |
genre |
polar night |
genre_facet |
polar night |
op_source |
Quarterly Journal of the Royal Meteorological Society volume 104, issue 441, page 595-614 ISSN 0035-9009 1477-870X |
op_rights |
http://onlinelibrary.wiley.com/termsAndConditions#vor |
op_doi |
https://doi.org/10.1002/qj.49710444105 |
container_title |
Quarterly Journal of the Royal Meteorological Society |
container_volume |
104 |
container_issue |
441 |
container_start_page |
595 |
op_container_end_page |
614 |
_version_ |
1800737038747566080 |