Climate change impact on ecosystems of Prince Edward Islands : role of oceanic mesoscale processes
The subantarctic Prince Edward Islands lie in the Antarctic Circumpolar Current, between the Subantarctic Front (SAF) and the Polar Front (PF). These fronts positions were found to be highly variable at interannual and monthly time scales and revealed a significant long-term southward trend in the r...
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ftunivbrest:oai:HAL:tel-01892140v1 2024-04-14T08:01:42+00:00 Climate change impact on ecosystems of Prince Edward Islands : role of oceanic mesoscale processes Impact du changement climatique sur les écosystèmes des îles du Prince Édouard : rôle des processus océaniques mésoéchelle Asdar, Sarah Laboratoire d'Océanographie Physique et Spatiale (LOPS) Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS) Université de Bretagne occidentale - Brest University of Cape Town Pierrick Penven 2018-07-06 https://theses.hal.science/tel-01892140 https://theses.hal.science/tel-01892140/document https://theses.hal.science/tel-01892140/file/These-2018-SML-Oceanographie_physique-ASDAR_Sarah.pdf en eng HAL CCSD NNT: 2018BRES0037 tel-01892140 https://theses.hal.science/tel-01892140 https://theses.hal.science/tel-01892140/document https://theses.hal.science/tel-01892140/file/These-2018-SML-Oceanographie_physique-ASDAR_Sarah.pdf info:eu-repo/semantics/OpenAccess https://theses.hal.science/tel-01892140 Earth Sciences. Université de Bretagne occidentale - Brest; University of Cape Town, 2018. English. ⟨NNT : 2018BRES0037⟩ Subantarctic islands Mesoscale eddy Subantarctic front Climate change Idealised ocean modelling Îles subantarctiques Tourbillon mésoéchelle Front subantarctique Changement climatique Modélisation idéalisée [SDU.STU]Sciences of the Universe [physics]/Earth Sciences info:eu-repo/semantics/doctoralThesis Theses 2018 ftunivbrest 2024-03-21T16:27:25Z The subantarctic Prince Edward Islands lie in the Antarctic Circumpolar Current, between the Subantarctic Front (SAF) and the Polar Front (PF). These fronts positions were found to be highly variable at interannual and monthly time scales and revealed a significant long-term southward trend in the region. The intense mesoscale activity, observed upstream the islands at the South West Indian Ridge, also showed an interannual and intra-annual variability as well a decrease in eddy kinetic energy over 24 years. At a more local scale, we highlighted that the archipelago’s environment was impacted by the mesoscale features produced upstream.Tides appeared to be another important driver of variability of the circulation in between the two islands.An idealised model configuration was designed for the Prince Edward Islands region to study the mesoscale eddy properties and the physical mechanisms of their formation at the ridge. The Eddy Available Potential Energy revealed a maximum of energy around 800 m depth, confirming the deep reaching characteristic of the eddy originated in the region and suggested the presence of a local energy source at this depth. This eddies activity was shown to be the result of a combination of barotropic and baroclinic instabilities occurring at the ridge.Finally, we investigated on the potential consequences of a southward shift of the SAF in the region of the islands.Because the model was idealised, it allowed us to simulate an SAF southward shift by shifting the initial and boundary conditions. The main result was the clear decrease of mesoscale activity in the region which could potentially impact the ecosystems of the Prince Edward Islands. L’archipel du Prince Édouard est situé dans le Courant Circumpolaire Antarctique, entre le Front Subantarctique (SAF) et le front polaire (PF). Les positions de ces fronts se sont révélées très variables aux échelles interannuelles et mensuelles et ont montré une tendance à long terme à migrer vers le sud dans la région. L'activité ... Doctoral or Postdoctoral Thesis Antarc* Antarctic Antarctique* Prince Edward Islands Université de Bretagne Occidentale: HAL Antarctic Indian The Antarctic |
institution |
Open Polar |
collection |
Université de Bretagne Occidentale: HAL |
op_collection_id |
ftunivbrest |
language |
English |
topic |
Subantarctic islands Mesoscale eddy Subantarctic front Climate change Idealised ocean modelling Îles subantarctiques Tourbillon mésoéchelle Front subantarctique Changement climatique Modélisation idéalisée [SDU.STU]Sciences of the Universe [physics]/Earth Sciences |
spellingShingle |
Subantarctic islands Mesoscale eddy Subantarctic front Climate change Idealised ocean modelling Îles subantarctiques Tourbillon mésoéchelle Front subantarctique Changement climatique Modélisation idéalisée [SDU.STU]Sciences of the Universe [physics]/Earth Sciences Asdar, Sarah Climate change impact on ecosystems of Prince Edward Islands : role of oceanic mesoscale processes |
topic_facet |
Subantarctic islands Mesoscale eddy Subantarctic front Climate change Idealised ocean modelling Îles subantarctiques Tourbillon mésoéchelle Front subantarctique Changement climatique Modélisation idéalisée [SDU.STU]Sciences of the Universe [physics]/Earth Sciences |
description |
The subantarctic Prince Edward Islands lie in the Antarctic Circumpolar Current, between the Subantarctic Front (SAF) and the Polar Front (PF). These fronts positions were found to be highly variable at interannual and monthly time scales and revealed a significant long-term southward trend in the region. The intense mesoscale activity, observed upstream the islands at the South West Indian Ridge, also showed an interannual and intra-annual variability as well a decrease in eddy kinetic energy over 24 years. At a more local scale, we highlighted that the archipelago’s environment was impacted by the mesoscale features produced upstream.Tides appeared to be another important driver of variability of the circulation in between the two islands.An idealised model configuration was designed for the Prince Edward Islands region to study the mesoscale eddy properties and the physical mechanisms of their formation at the ridge. The Eddy Available Potential Energy revealed a maximum of energy around 800 m depth, confirming the deep reaching characteristic of the eddy originated in the region and suggested the presence of a local energy source at this depth. This eddies activity was shown to be the result of a combination of barotropic and baroclinic instabilities occurring at the ridge.Finally, we investigated on the potential consequences of a southward shift of the SAF in the region of the islands.Because the model was idealised, it allowed us to simulate an SAF southward shift by shifting the initial and boundary conditions. The main result was the clear decrease of mesoscale activity in the region which could potentially impact the ecosystems of the Prince Edward Islands. L’archipel du Prince Édouard est situé dans le Courant Circumpolaire Antarctique, entre le Front Subantarctique (SAF) et le front polaire (PF). Les positions de ces fronts se sont révélées très variables aux échelles interannuelles et mensuelles et ont montré une tendance à long terme à migrer vers le sud dans la région. L'activité ... |
author2 |
Laboratoire d'Océanographie Physique et Spatiale (LOPS) Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS) Université de Bretagne occidentale - Brest University of Cape Town Pierrick Penven |
format |
Doctoral or Postdoctoral Thesis |
author |
Asdar, Sarah |
author_facet |
Asdar, Sarah |
author_sort |
Asdar, Sarah |
title |
Climate change impact on ecosystems of Prince Edward Islands : role of oceanic mesoscale processes |
title_short |
Climate change impact on ecosystems of Prince Edward Islands : role of oceanic mesoscale processes |
title_full |
Climate change impact on ecosystems of Prince Edward Islands : role of oceanic mesoscale processes |
title_fullStr |
Climate change impact on ecosystems of Prince Edward Islands : role of oceanic mesoscale processes |
title_full_unstemmed |
Climate change impact on ecosystems of Prince Edward Islands : role of oceanic mesoscale processes |
title_sort |
climate change impact on ecosystems of prince edward islands : role of oceanic mesoscale processes |
publisher |
HAL CCSD |
publishDate |
2018 |
url |
https://theses.hal.science/tel-01892140 https://theses.hal.science/tel-01892140/document https://theses.hal.science/tel-01892140/file/These-2018-SML-Oceanographie_physique-ASDAR_Sarah.pdf |
geographic |
Antarctic Indian The Antarctic |
geographic_facet |
Antarctic Indian The Antarctic |
genre |
Antarc* Antarctic Antarctique* Prince Edward Islands |
genre_facet |
Antarc* Antarctic Antarctique* Prince Edward Islands |
op_source |
https://theses.hal.science/tel-01892140 Earth Sciences. Université de Bretagne occidentale - Brest; University of Cape Town, 2018. English. ⟨NNT : 2018BRES0037⟩ |
op_relation |
NNT: 2018BRES0037 tel-01892140 https://theses.hal.science/tel-01892140 https://theses.hal.science/tel-01892140/document https://theses.hal.science/tel-01892140/file/These-2018-SML-Oceanographie_physique-ASDAR_Sarah.pdf |
op_rights |
info:eu-repo/semantics/OpenAccess |
_version_ |
1796310399799263232 |