Formation of maritime convergence zones within cold air outbreaks due to the shape of the coastline or sea ice edge
Abstract Maritime cold air outbreaks often feature convergence zones that provide a conducive environment for the development of polar mesoscale cyclones and polar lows. This study examines the formation mechanisms of these convergence zones in cold air outbreaks downstream of a coastline or sea‐ice...
Published in: | Quarterly Journal of the Royal Meteorological Society |
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crwiley:10.1002/qj.4324 2024-06-02T08:14:17+00:00 Formation of maritime convergence zones within cold air outbreaks due to the shape of the coastline or sea ice edge Watanabe, Shun‐ichi I. Niino, Hiroshi Spengler, Thomas Japan Society for the Promotion of Science 2022 http://dx.doi.org/10.1002/qj.4324 https://onlinelibrary.wiley.com/doi/pdf/10.1002/qj.4324 https://onlinelibrary.wiley.com/doi/full-xml/10.1002/qj.4324 https://rmets.onlinelibrary.wiley.com/doi/pdf/10.1002/qj.4324 en eng Wiley http://creativecommons.org/licenses/by/4.0/ Quarterly Journal of the Royal Meteorological Society volume 148, issue 746, page 2546-2562 ISSN 0035-9009 1477-870X journal-article 2022 crwiley https://doi.org/10.1002/qj.4324 2024-05-03T12:03:02Z Abstract Maritime cold air outbreaks often feature convergence zones that provide a conducive environment for the development of polar mesoscale cyclones and polar lows. This study examines the formation mechanisms of these convergence zones in cold air outbreaks downstream of a coastline or sea‐ice edge. A simplified configuration in which the coastline or sea‐ice edge is approximated by a line featuring a bend with an angle is examined using analytic solutions and idealised numerical simulations. The bend of the coastline causes differences in the fetch over which air parcels travel, causing a warm wedge of air downstream of the bend due to differential airmass transformations. The warm wedge is associated with a pressure trough that leads to convergence in the presence of surface friction. The analytic model captures this mechanism and compares well with the idealised numerical simulations. Condensational heating associated with moist convection enhances vertical motions and thus intensifies the horizontal convergence. The idealised numerical simulations also reproduce an asymmetry in the vertical shear of the horizontal wind across the convergence zone, which explains the transverse cloud streets downstream to the left of the convergence zone. Article in Journal/Newspaper Sea ice Wiley Online Library Quarterly Journal of the Royal Meteorological Society 148 746 2546 2562 |
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Open Polar |
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Wiley Online Library |
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crwiley |
language |
English |
description |
Abstract Maritime cold air outbreaks often feature convergence zones that provide a conducive environment for the development of polar mesoscale cyclones and polar lows. This study examines the formation mechanisms of these convergence zones in cold air outbreaks downstream of a coastline or sea‐ice edge. A simplified configuration in which the coastline or sea‐ice edge is approximated by a line featuring a bend with an angle is examined using analytic solutions and idealised numerical simulations. The bend of the coastline causes differences in the fetch over which air parcels travel, causing a warm wedge of air downstream of the bend due to differential airmass transformations. The warm wedge is associated with a pressure trough that leads to convergence in the presence of surface friction. The analytic model captures this mechanism and compares well with the idealised numerical simulations. Condensational heating associated with moist convection enhances vertical motions and thus intensifies the horizontal convergence. The idealised numerical simulations also reproduce an asymmetry in the vertical shear of the horizontal wind across the convergence zone, which explains the transverse cloud streets downstream to the left of the convergence zone. |
author2 |
Japan Society for the Promotion of Science |
format |
Article in Journal/Newspaper |
author |
Watanabe, Shun‐ichi I. Niino, Hiroshi Spengler, Thomas |
spellingShingle |
Watanabe, Shun‐ichi I. Niino, Hiroshi Spengler, Thomas Formation of maritime convergence zones within cold air outbreaks due to the shape of the coastline or sea ice edge |
author_facet |
Watanabe, Shun‐ichi I. Niino, Hiroshi Spengler, Thomas |
author_sort |
Watanabe, Shun‐ichi I. |
title |
Formation of maritime convergence zones within cold air outbreaks due to the shape of the coastline or sea ice edge |
title_short |
Formation of maritime convergence zones within cold air outbreaks due to the shape of the coastline or sea ice edge |
title_full |
Formation of maritime convergence zones within cold air outbreaks due to the shape of the coastline or sea ice edge |
title_fullStr |
Formation of maritime convergence zones within cold air outbreaks due to the shape of the coastline or sea ice edge |
title_full_unstemmed |
Formation of maritime convergence zones within cold air outbreaks due to the shape of the coastline or sea ice edge |
title_sort |
formation of maritime convergence zones within cold air outbreaks due to the shape of the coastline or sea ice edge |
publisher |
Wiley |
publishDate |
2022 |
url |
http://dx.doi.org/10.1002/qj.4324 https://onlinelibrary.wiley.com/doi/pdf/10.1002/qj.4324 https://onlinelibrary.wiley.com/doi/full-xml/10.1002/qj.4324 https://rmets.onlinelibrary.wiley.com/doi/pdf/10.1002/qj.4324 |
genre |
Sea ice |
genre_facet |
Sea ice |
op_source |
Quarterly Journal of the Royal Meteorological Society volume 148, issue 746, page 2546-2562 ISSN 0035-9009 1477-870X |
op_rights |
http://creativecommons.org/licenses/by/4.0/ |
op_doi |
https://doi.org/10.1002/qj.4324 |
container_title |
Quarterly Journal of the Royal Meteorological Society |
container_volume |
148 |
container_issue |
746 |
container_start_page |
2546 |
op_container_end_page |
2562 |
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1800738072985337856 |