Spatio-temporal characteristics of Agulhas leakage: a model inter-comparison study
International audience Investigating the variability of Agulhas leakage, the volume transport of water from the Indian Ocean to the South Atlantic Ocean, is highly relevant due to its potential contribution to the Atlantic Meridional Overturning Circulation as well as the global circulation of heat...
Published in: | Climate Dynamics |
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Main Authors: | , , , , , |
Other Authors: | , , , , , , , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
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HAL CCSD
2017
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Subjects: | |
Online Access: | https://hal.science/hal-01491458 https://doi.org/10.1007/s00382-016-3193-5 |
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ftmuseumnhn:oai:HAL:hal-01491458v1 |
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Open Polar |
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Muséum National d'Histoire Naturelle (MNHM): HAL |
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ftmuseumnhn |
language |
English |
topic |
Agulhas system Ocean variability Agulhas leakage ClimateModel inter-comparison [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph] |
spellingShingle |
Agulhas system Ocean variability Agulhas leakage ClimateModel inter-comparison [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph] Holton, L. Deshayes, Julie Backeberg, B. C. Loveday, B. R. Hermes, J. C. Reason, C. J. C. Spatio-temporal characteristics of Agulhas leakage: a model inter-comparison study |
topic_facet |
Agulhas system Ocean variability Agulhas leakage ClimateModel inter-comparison [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph] |
description |
International audience Investigating the variability of Agulhas leakage, the volume transport of water from the Indian Ocean to the South Atlantic Ocean, is highly relevant due to its potential contribution to the Atlantic Meridional Overturning Circulation as well as the global circulation of heat and salt and hence global climate. Quantifying Agulhas leakage is challenging due to the non-linear nature of this process; current observations are insufficient to estimate its variability and ocean models all have biases in this region, even at high resolution . An Eulerian threshold integration method is developed to examine the mechanisms of Agulhas leakage variability in six ocean model simulations of varying resolution. This intercomparison, based on the circulation and thermohaline structure at the Good Hope line, a transect to the south west of the southern tip of Africa , is used to identify features that are robust regardless of the model used and takes into account the thermohaline biases of each model. When determined by a passive tracer method, 60 % of the magnitude of Agulhas leakage is captured and more than 80 % of its temporal fluctuations, suggesting that the method is appropriate for investigating the variability of Agulhas leakage. In all simulations but one, the major driver of variability is associated with mesoscale features passing through the section. High resolution (<1/10∘) hindcast models agree on the temporal (2–4 cycles per year) and spatial (300–500 km) scales of these features corresponding to observed Agulhas Rings. Coarser resolution models (<1/4∘) reproduce similar time scale of variability of Agulhas leakage in spite of their difficulties in representing the Agulhas rings properties. A coarser resolution climate model (2∘) does not resolve the spatio-temporal mechanism of variability of Agulhas leakage. Hence it is expected to underestimate the contribution of Agulhas Current System to climate variability. |
author2 |
ICEMASA University of Cape Town Nucleus for European Modeling of the Ocean (NEMO R&D ) Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN) Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)) École normale supérieure - Paris (ENS-PSL) Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL) Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)) Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS) Department of Oceanography Nansen-Tutu Centre for Marine Environmental Research |
format |
Article in Journal/Newspaper |
author |
Holton, L. Deshayes, Julie Backeberg, B. C. Loveday, B. R. Hermes, J. C. Reason, C. J. C. |
author_facet |
Holton, L. Deshayes, Julie Backeberg, B. C. Loveday, B. R. Hermes, J. C. Reason, C. J. C. |
author_sort |
Holton, L. |
title |
Spatio-temporal characteristics of Agulhas leakage: a model inter-comparison study |
title_short |
Spatio-temporal characteristics of Agulhas leakage: a model inter-comparison study |
title_full |
Spatio-temporal characteristics of Agulhas leakage: a model inter-comparison study |
title_fullStr |
Spatio-temporal characteristics of Agulhas leakage: a model inter-comparison study |
title_full_unstemmed |
Spatio-temporal characteristics of Agulhas leakage: a model inter-comparison study |
title_sort |
spatio-temporal characteristics of agulhas leakage: a model inter-comparison study |
publisher |
HAL CCSD |
publishDate |
2017 |
url |
https://hal.science/hal-01491458 https://doi.org/10.1007/s00382-016-3193-5 |
genre |
South Atlantic Ocean |
genre_facet |
South Atlantic Ocean |
op_source |
ISSN: 0930-7575 EISSN: 1432-0894 Climate Dynamics https://hal.science/hal-01491458 Climate Dynamics, 2017, 48 (7-8), pp.2107-2121. ⟨10.1007/s00382-016-3193-5⟩ |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1007/s00382-016-3193-5 hal-01491458 https://hal.science/hal-01491458 doi:10.1007/s00382-016-3193-5 |
op_doi |
https://doi.org/10.1007/s00382-016-3193-5 |
container_title |
Climate Dynamics |
container_volume |
48 |
container_issue |
7-8 |
container_start_page |
2107 |
op_container_end_page |
2121 |
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1799466863334260736 |
spelling |
ftmuseumnhn:oai:HAL:hal-01491458v1 2024-05-19T07:48:34+00:00 Spatio-temporal characteristics of Agulhas leakage: a model inter-comparison study Holton, L. Deshayes, Julie Backeberg, B. C. Loveday, B. R. Hermes, J. C. Reason, C. J. C. ICEMASA University of Cape Town Nucleus for European Modeling of the Ocean (NEMO R&D ) Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN) Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)) École normale supérieure - Paris (ENS-PSL) Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL) Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)) Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS) Department of Oceanography Nansen-Tutu Centre for Marine Environmental Research 2017 https://hal.science/hal-01491458 https://doi.org/10.1007/s00382-016-3193-5 en eng HAL CCSD Springer Verlag info:eu-repo/semantics/altIdentifier/doi/10.1007/s00382-016-3193-5 hal-01491458 https://hal.science/hal-01491458 doi:10.1007/s00382-016-3193-5 ISSN: 0930-7575 EISSN: 1432-0894 Climate Dynamics https://hal.science/hal-01491458 Climate Dynamics, 2017, 48 (7-8), pp.2107-2121. ⟨10.1007/s00382-016-3193-5⟩ Agulhas system Ocean variability Agulhas leakage ClimateModel inter-comparison [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph] info:eu-repo/semantics/article Journal articles 2017 ftmuseumnhn https://doi.org/10.1007/s00382-016-3193-5 2024-04-25T00:54:19Z International audience Investigating the variability of Agulhas leakage, the volume transport of water from the Indian Ocean to the South Atlantic Ocean, is highly relevant due to its potential contribution to the Atlantic Meridional Overturning Circulation as well as the global circulation of heat and salt and hence global climate. Quantifying Agulhas leakage is challenging due to the non-linear nature of this process; current observations are insufficient to estimate its variability and ocean models all have biases in this region, even at high resolution . An Eulerian threshold integration method is developed to examine the mechanisms of Agulhas leakage variability in six ocean model simulations of varying resolution. This intercomparison, based on the circulation and thermohaline structure at the Good Hope line, a transect to the south west of the southern tip of Africa , is used to identify features that are robust regardless of the model used and takes into account the thermohaline biases of each model. When determined by a passive tracer method, 60 % of the magnitude of Agulhas leakage is captured and more than 80 % of its temporal fluctuations, suggesting that the method is appropriate for investigating the variability of Agulhas leakage. In all simulations but one, the major driver of variability is associated with mesoscale features passing through the section. High resolution (<1/10∘) hindcast models agree on the temporal (2–4 cycles per year) and spatial (300–500 km) scales of these features corresponding to observed Agulhas Rings. Coarser resolution models (<1/4∘) reproduce similar time scale of variability of Agulhas leakage in spite of their difficulties in representing the Agulhas rings properties. A coarser resolution climate model (2∘) does not resolve the spatio-temporal mechanism of variability of Agulhas leakage. Hence it is expected to underestimate the contribution of Agulhas Current System to climate variability. Article in Journal/Newspaper South Atlantic Ocean Muséum National d'Histoire Naturelle (MNHM): HAL Climate Dynamics 48 7-8 2107 2121 |