Characteristics of summer airflow over the Antarctic Peninsula in response to recent strengthening of westerly circumpolar winds
Summer near-surface temperatures over the northeast coast of the Antarctic Peninsula have increased by more than 2 degrees C over the past 40 years, a temperature increase 3 times greater than that on the northwest coast. Recent analysis has shown a strong correlation between this striking warming t...
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Online Access: | https://lirias.kuleuven.be/handle/123456789/260715 https://doi.org/10.1175/2007JAS2498.1 |
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ftunivleuven:oai:lirias.kuleuven.be:123456789/260715 2023-05-15T14:02:22+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, Joel Wang, Chang-Gui Van Lipzig, Nicole Cresswell, Doug King, John C 2008-04 https://lirias.kuleuven.be/handle/123456789/260715 https://doi.org/10.1175/2007JAS2498.1 en eng Amer meteorological soc Journal of the atmospheric sciences vol:65 issue:4 pages:1396-1413 https://lirias.kuleuven.be/handle/123456789/260715 0022-4928 doi:10.1175/2007JAS2498.1 hemisphere annular mode stratified flow orographic drag climate-change laboratory simulation 3-dimensional hill stagnation points stable flows temperatures variability Antarctic Peninsula summer warming trend strengthening winds SAM Larsen Ice Shelf Description (Metadata) only IT article 2008 ftunivleuven https://doi.org/10.1175/2007JAS2498.1 2017-06-02T19:18:07Z Summer near-surface temperatures over the northeast coast of the Antarctic Peninsula have increased by more than 2 degrees C over the past 40 years, a temperature increase 3 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 are 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, that is, 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. status: published Article in Journal/Newspaper Antarc* Antarctic Antarctic Peninsula Ice Shelf Larsen Ice Shelf KU Leuven: Lirias 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 |
KU Leuven: Lirias |
op_collection_id |
ftunivleuven |
language |
English |
topic |
hemisphere annular mode stratified flow orographic drag climate-change laboratory simulation 3-dimensional hill stagnation points stable flows temperatures variability Antarctic Peninsula summer warming trend strengthening winds SAM Larsen Ice Shelf |
spellingShingle |
hemisphere annular mode stratified flow orographic drag climate-change laboratory simulation 3-dimensional hill stagnation points stable flows temperatures variability Antarctic Peninsula summer warming trend strengthening winds SAM Larsen Ice Shelf Orr, Andrew Marshall, Gareth J Hunt, Julian C. R Sommeria, Joel Wang, Chang-Gui Van Lipzig, Nicole Cresswell, Doug King, John C Characteristics of summer airflow over the Antarctic Peninsula in response to recent strengthening of westerly circumpolar winds |
topic_facet |
hemisphere annular mode stratified flow orographic drag climate-change laboratory simulation 3-dimensional hill stagnation points stable flows temperatures variability Antarctic Peninsula summer warming trend strengthening winds SAM Larsen Ice Shelf |
description |
Summer near-surface temperatures over the northeast coast of the Antarctic Peninsula have increased by more than 2 degrees C over the past 40 years, a temperature increase 3 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 are 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, that is, 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. status: published |
format |
Article in Journal/Newspaper |
author |
Orr, Andrew Marshall, Gareth J Hunt, Julian C. R Sommeria, Joel Wang, Chang-Gui Van Lipzig, Nicole Cresswell, Doug King, John C |
author_facet |
Orr, Andrew Marshall, Gareth J Hunt, Julian C. R Sommeria, Joel Wang, Chang-Gui Van Lipzig, Nicole Cresswell, Doug King, John C |
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 |
Amer meteorological soc |
publishDate |
2008 |
url |
https://lirias.kuleuven.be/handle/123456789/260715 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_relation |
Journal of the atmospheric sciences vol:65 issue:4 pages:1396-1413 https://lirias.kuleuven.be/handle/123456789/260715 0022-4928 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_ |
1766272601177456640 |