Characteristics of summer airflow over the Antarctic peninsula in response to recent strengthening of westerly circumpolar winds
International audience Summer near-surface temperatures over the northeast coast of the Antarctic Peninsula have increased by more than 2↓C over the past 40 years, a temperature increase three times greater than that on the northwest coast. Recent analysis has shown a strong correlation between this...
Published in: | Journal of the Atmospheric Sciences |
---|---|
Main Authors: | , , , , , , , |
Other Authors: | , , , , , , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
HAL CCSD
2008
|
Subjects: | |
Online Access: | https://hal.science/hal-00351634 https://doi.org/10.1175/2007JAS2498.1 |
id |
ftunivnantes:oai:HAL:hal-00351634v1 |
---|---|
record_format |
openpolar |
spelling |
ftunivnantes:oai:HAL:hal-00351634v1 2023-05-15T13:46:38+02:00 Characteristics of summer airflow over the Antarctic peninsula in response to recent strengthening of westerly circumpolar winds Orr, Andrew Marshall, Gareth J. Hunt, Julian C. R. Sommeria, Joël Wang, Chang-Gui van Lipzig, Nicole Cresswell, Doug King, John Centre for Polar Observation & Modelling University College of London London (UCL) British Antarctic Survey (BAS) Natural Environment Research Council (NERC) Laboratoire des Écoulements Géophysiques et Industriels Grenoble (LEGI) Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS) Department of Meteorology Reading University of Reading (UOR) Physical and Regional Geography Research Group K. U. Leuven 2008 https://hal.science/hal-00351634 https://doi.org/10.1175/2007JAS2498.1 en eng HAL CCSD American Meteorological Society info:eu-repo/semantics/altIdentifier/doi/10.1175/2007JAS2498.1 hal-00351634 https://hal.science/hal-00351634 doi:10.1175/2007JAS2498.1 ISSN: 0022-4928 EISSN: 1520-0469 Journal of the Atmospheric Sciences https://hal.science/hal-00351634 Journal of the Atmospheric Sciences, 2008, 65, pp.1396-1413. ⟨10.1175/2007JAS2498.1⟩ [PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph] [SPI.MECA.MEFL]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Fluids mechanics [physics.class-ph] [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere info:eu-repo/semantics/article Journal articles 2008 ftunivnantes https://doi.org/10.1175/2007JAS2498.1 2023-02-08T03:24:46Z International audience Summer near-surface temperatures over the northeast coast of the Antarctic Peninsula have increased by more than 2↓C over the past 40 years, a temperature increase three times greater than that on the northwest coast. Recent analysis has shown a strong correlation between this striking warming trend and significant change in the summer Southern Hemisphere Annular Mode (SAM), which has resulted in greatly increased summer westerlies across the northern Peninsula. It has been proposed that the strengthening westerlies have resulted in increased vertical deflection of relatively warm maritime air over the northern Peninsula, contributing significantly to the observed warming and the recent collapse of northern sections of the Larsen Ice Shelf. In this study, laboratory and numerical modeling of airflow incident to the Peninsula is employed to further understand this mechanism. It is shown that the effect of the strengthening westerlies has led to a distinct transition from a 'blocked' regime to a 'flow-over' regime, i.e. confirmation of the proposed warming mechanism. The blocked regime is dominated by flow stagnation upstream (i.e. little vertical deflection) and consequent lateral deflection of flow along the western side of the Peninsula. The flow-over regime is dominated by vertical deflection of mid/upper-level air over the Peninsula, with strong downslope winds following closely to the leeward slope transporting this air (which warms adiabatically as it descends) to the near-surface of the northeast Peninsula. The strong rotation typical of high latitudes considerably increases the flow over the Peninsula, particularly strengthening it over the southern side (verified by aircraft measurements), suggesting that the warming trend is not solely confined to the northeast. Globally, flow regime transitions such as this may be responsible for other local climate variations. Article in Journal/Newspaper Antarc* Antarctic Antarctic Peninsula Ice Shelf Larsen Ice Shelf Université de Nantes: HAL-UNIV-NANTES Antarctic Antarctic Peninsula Larsen Ice Shelf ENVELOPE(-62.500,-62.500,-67.500,-67.500) The Antarctic Journal of the Atmospheric Sciences 65 4 1396 1413 |
institution |
Open Polar |
collection |
Université de Nantes: HAL-UNIV-NANTES |
op_collection_id |
ftunivnantes |
language |
English |
topic |
[PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph] [SPI.MECA.MEFL]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Fluids mechanics [physics.class-ph] [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere |
spellingShingle |
[PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph] [SPI.MECA.MEFL]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Fluids mechanics [physics.class-ph] [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere Orr, Andrew Marshall, Gareth J. Hunt, Julian C. R. Sommeria, Joël Wang, Chang-Gui van Lipzig, Nicole Cresswell, Doug King, John Characteristics of summer airflow over the Antarctic peninsula in response to recent strengthening of westerly circumpolar winds |
topic_facet |
[PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph] [SPI.MECA.MEFL]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Fluids mechanics [physics.class-ph] [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere |
description |
International audience Summer near-surface temperatures over the northeast coast of the Antarctic Peninsula have increased by more than 2↓C over the past 40 years, a temperature increase three times greater than that on the northwest coast. Recent analysis has shown a strong correlation between this striking warming trend and significant change in the summer Southern Hemisphere Annular Mode (SAM), which has resulted in greatly increased summer westerlies across the northern Peninsula. It has been proposed that the strengthening westerlies have resulted in increased vertical deflection of relatively warm maritime air over the northern Peninsula, contributing significantly to the observed warming and the recent collapse of northern sections of the Larsen Ice Shelf. In this study, laboratory and numerical modeling of airflow incident to the Peninsula is employed to further understand this mechanism. It is shown that the effect of the strengthening westerlies has led to a distinct transition from a 'blocked' regime to a 'flow-over' regime, i.e. confirmation of the proposed warming mechanism. The blocked regime is dominated by flow stagnation upstream (i.e. little vertical deflection) and consequent lateral deflection of flow along the western side of the Peninsula. The flow-over regime is dominated by vertical deflection of mid/upper-level air over the Peninsula, with strong downslope winds following closely to the leeward slope transporting this air (which warms adiabatically as it descends) to the near-surface of the northeast Peninsula. The strong rotation typical of high latitudes considerably increases the flow over the Peninsula, particularly strengthening it over the southern side (verified by aircraft measurements), suggesting that the warming trend is not solely confined to the northeast. Globally, flow regime transitions such as this may be responsible for other local climate variations. |
author2 |
Centre for Polar Observation & Modelling University College of London London (UCL) British Antarctic Survey (BAS) Natural Environment Research Council (NERC) Laboratoire des Écoulements Géophysiques et Industriels Grenoble (LEGI) Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS) Department of Meteorology Reading University of Reading (UOR) Physical and Regional Geography Research Group K. U. Leuven |
format |
Article in Journal/Newspaper |
author |
Orr, Andrew Marshall, Gareth J. Hunt, Julian C. R. Sommeria, Joël Wang, Chang-Gui van Lipzig, Nicole Cresswell, Doug King, John |
author_facet |
Orr, Andrew Marshall, Gareth J. Hunt, Julian C. R. Sommeria, Joël Wang, Chang-Gui van Lipzig, Nicole Cresswell, Doug King, John |
author_sort |
Orr, Andrew |
title |
Characteristics of summer airflow over the Antarctic peninsula in response to recent strengthening of westerly circumpolar winds |
title_short |
Characteristics of summer airflow over the Antarctic peninsula in response to recent strengthening of westerly circumpolar winds |
title_full |
Characteristics of summer airflow over the Antarctic peninsula in response to recent strengthening of westerly circumpolar winds |
title_fullStr |
Characteristics of summer airflow over the Antarctic peninsula in response to recent strengthening of westerly circumpolar winds |
title_full_unstemmed |
Characteristics of summer airflow over the Antarctic peninsula in response to recent strengthening of westerly circumpolar winds |
title_sort |
characteristics of summer airflow over the antarctic peninsula in response to recent strengthening of westerly circumpolar winds |
publisher |
HAL CCSD |
publishDate |
2008 |
url |
https://hal.science/hal-00351634 https://doi.org/10.1175/2007JAS2498.1 |
long_lat |
ENVELOPE(-62.500,-62.500,-67.500,-67.500) |
geographic |
Antarctic Antarctic Peninsula Larsen Ice Shelf The Antarctic |
geographic_facet |
Antarctic Antarctic Peninsula Larsen Ice Shelf The Antarctic |
genre |
Antarc* Antarctic Antarctic Peninsula Ice Shelf Larsen Ice Shelf |
genre_facet |
Antarc* Antarctic Antarctic Peninsula Ice Shelf Larsen Ice Shelf |
op_source |
ISSN: 0022-4928 EISSN: 1520-0469 Journal of the Atmospheric Sciences https://hal.science/hal-00351634 Journal of the Atmospheric Sciences, 2008, 65, pp.1396-1413. ⟨10.1175/2007JAS2498.1⟩ |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1175/2007JAS2498.1 hal-00351634 https://hal.science/hal-00351634 doi:10.1175/2007JAS2498.1 |
op_doi |
https://doi.org/10.1175/2007JAS2498.1 |
container_title |
Journal of the Atmospheric Sciences |
container_volume |
65 |
container_issue |
4 |
container_start_page |
1396 |
op_container_end_page |
1413 |
_version_ |
1766244729103581184 |