An easterly tip jet off Cape Farewell, Greenland. II: Simulations and dynamics
An easterly tip jet that occurred on 21 February 2007 off Cape Farewell, Greenland, is examined. In Part I of this article aircraft observations were described. Now, in Part II, numerical simulations and an analysis of the dynamical forcing mechanisms are presented. The simulations make use of a lim...
Published in: | Quarterly Journal of the Royal Meteorological Society |
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ftuniveastangl:oai:ueaeprints.uea.ac.uk:24334 2023-05-15T15:51:49+02:00 An easterly tip jet off Cape Farewell, Greenland. II: Simulations and dynamics Outten, SD Renfrew, IA Petersen, GN 2009 application/pdf https://ueaeprints.uea.ac.uk/id/eprint/24334/ https://ueaeprints.uea.ac.uk/id/eprint/24334/1/outten_etal_ETJ_dynamics_QJRMS_2009.pdf https://doi.org/10.1002/qj.531 en eng https://ueaeprints.uea.ac.uk/id/eprint/24334/1/outten_etal_ETJ_dynamics_QJRMS_2009.pdf Outten, SD, Renfrew, IA and Petersen, GN (2009) An easterly tip jet off Cape Farewell, Greenland. II: Simulations and dynamics. Quarterly Journal of the Royal Meteorological Society, 135 (645). pp. 1934-1949. ISSN 1477-870X doi:10.1002/qj.531 Article PeerReviewed 2009 ftuniveastangl https://doi.org/10.1002/qj.531 2023-03-23T23:31:28Z An easterly tip jet that occurred on 21 February 2007 off Cape Farewell, Greenland, is examined. In Part I of this article aircraft observations were described. Now, in Part II, numerical simulations and an analysis of the dynamical forcing mechanisms are presented. The simulations make use of a limited-area 12 km resolution configuration of the Met Office's Unified Model. Sea-surface temperatures and sea-ice concentrations have been replaced using the Operational Sea Surface Temperature and Sea Ice Analysis (OSTIA) product, addressing a boundary-layer temperature bias, while roughness lengths over sea ice have been updated, addressing a wind-speed bias. These modifications ensured a reasonably accurate simulation: generally within 1–2 K and 2–3 m s-1 when compared with dropsonde observations. A momentum-budget analysis along a curved locus through the core of the jet has been derived. Off southeast Greenland, the easterly tip jet was in cross-jet geostrophic balance, but was being accelerated downstream by an along-jet pressure gradient. Over the curved part of the locus, as the jet rounded Cape Farewell, a cross-jet residual suggests that the jet was unbalanced at the height of the jet core. This residual decreases with height so that an approximate gradient wind balance applies in the upper part of the jet. The anticyclonic curvature, characteristic of easterly tip jets, was caused by a dramatic decrease in the cross-jet pressure-gradient force at the end of the barrier, after which the jet aligned with the synoptic-scale isobars and returned to approximate geostrophic balance. The momentum budget is shown to be robust and applicable to other cases. Article in Journal/Newspaper Cape Farewell Greenland Sea ice University of East Anglia: UEA Digital Repository Greenland Quarterly Journal of the Royal Meteorological Society 135 645 1934 1949 |
institution |
Open Polar |
collection |
University of East Anglia: UEA Digital Repository |
op_collection_id |
ftuniveastangl |
language |
English |
description |
An easterly tip jet that occurred on 21 February 2007 off Cape Farewell, Greenland, is examined. In Part I of this article aircraft observations were described. Now, in Part II, numerical simulations and an analysis of the dynamical forcing mechanisms are presented. The simulations make use of a limited-area 12 km resolution configuration of the Met Office's Unified Model. Sea-surface temperatures and sea-ice concentrations have been replaced using the Operational Sea Surface Temperature and Sea Ice Analysis (OSTIA) product, addressing a boundary-layer temperature bias, while roughness lengths over sea ice have been updated, addressing a wind-speed bias. These modifications ensured a reasonably accurate simulation: generally within 1–2 K and 2–3 m s-1 when compared with dropsonde observations. A momentum-budget analysis along a curved locus through the core of the jet has been derived. Off southeast Greenland, the easterly tip jet was in cross-jet geostrophic balance, but was being accelerated downstream by an along-jet pressure gradient. Over the curved part of the locus, as the jet rounded Cape Farewell, a cross-jet residual suggests that the jet was unbalanced at the height of the jet core. This residual decreases with height so that an approximate gradient wind balance applies in the upper part of the jet. The anticyclonic curvature, characteristic of easterly tip jets, was caused by a dramatic decrease in the cross-jet pressure-gradient force at the end of the barrier, after which the jet aligned with the synoptic-scale isobars and returned to approximate geostrophic balance. The momentum budget is shown to be robust and applicable to other cases. |
format |
Article in Journal/Newspaper |
author |
Outten, SD Renfrew, IA Petersen, GN |
spellingShingle |
Outten, SD Renfrew, IA Petersen, GN An easterly tip jet off Cape Farewell, Greenland. II: Simulations and dynamics |
author_facet |
Outten, SD Renfrew, IA Petersen, GN |
author_sort |
Outten, SD |
title |
An easterly tip jet off Cape Farewell, Greenland. II: Simulations and dynamics |
title_short |
An easterly tip jet off Cape Farewell, Greenland. II: Simulations and dynamics |
title_full |
An easterly tip jet off Cape Farewell, Greenland. II: Simulations and dynamics |
title_fullStr |
An easterly tip jet off Cape Farewell, Greenland. II: Simulations and dynamics |
title_full_unstemmed |
An easterly tip jet off Cape Farewell, Greenland. II: Simulations and dynamics |
title_sort |
easterly tip jet off cape farewell, greenland. ii: simulations and dynamics |
publishDate |
2009 |
url |
https://ueaeprints.uea.ac.uk/id/eprint/24334/ https://ueaeprints.uea.ac.uk/id/eprint/24334/1/outten_etal_ETJ_dynamics_QJRMS_2009.pdf https://doi.org/10.1002/qj.531 |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Cape Farewell Greenland Sea ice |
genre_facet |
Cape Farewell Greenland Sea ice |
op_relation |
https://ueaeprints.uea.ac.uk/id/eprint/24334/1/outten_etal_ETJ_dynamics_QJRMS_2009.pdf Outten, SD, Renfrew, IA and Petersen, GN (2009) An easterly tip jet off Cape Farewell, Greenland. II: Simulations and dynamics. Quarterly Journal of the Royal Meteorological Society, 135 (645). pp. 1934-1949. ISSN 1477-870X doi:10.1002/qj.531 |
op_doi |
https://doi.org/10.1002/qj.531 |
container_title |
Quarterly Journal of the Royal Meteorological Society |
container_volume |
135 |
container_issue |
645 |
container_start_page |
1934 |
op_container_end_page |
1949 |
_version_ |
1766387200484704256 |