How does the low-frequency Equatorial Kelvin Wave activity, local ocean stratification, and coastal winds modulate the south-eastern interannual Atlantic variability ? [résumé]
ICAWA : International Conference AWA, Lanzarote, ESP, 17-/04/2018 - 20/04/2018 The objective of this study is to describe the low-frequency modulation of the Equatorial Kelvin Wave (EKW) activity in the tropical Atlantic as well as the low-frequency modulation of the local stratification and coastal...
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Language: | English |
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2018
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Online Access: | https://hal.science/hal-02777723 |
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ftunivnantes:oai:HAL:hal-02777723v1 |
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openpolar |
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Open Polar |
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Université de Nantes: HAL-UNIV-NANTES |
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ftunivnantes |
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English |
topic |
AFRIQUE SUBSAHARIENNE ANGOLA NAMIBIE ATLANTIQUE [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [SDE.MCG]Environmental Sciences/Global Changes |
spellingShingle |
AFRIQUE SUBSAHARIENNE ANGOLA NAMIBIE ATLANTIQUE [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [SDE.MCG]Environmental Sciences/Global Changes Bachelery, M.L. Illig, Serena Rouault, M. How does the low-frequency Equatorial Kelvin Wave activity, local ocean stratification, and coastal winds modulate the south-eastern interannual Atlantic variability ? [résumé] |
topic_facet |
AFRIQUE SUBSAHARIENNE ANGOLA NAMIBIE ATLANTIQUE [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [SDE.MCG]Environmental Sciences/Global Changes |
description |
ICAWA : International Conference AWA, Lanzarote, ESP, 17-/04/2018 - 20/04/2018 The objective of this study is to describe the low-frequency modulation of the Equatorial Kelvin Wave (EKW) activity in the tropical Atlantic as well as the low-frequency modulation of the local stratification and coastal winds along the coast of south-western Africa. We aim at investigating the control of these forcings in modulating the oceanic interannual variability off the coasts of Angola/Namibia and the phenomenology of Benguela Niño/Niña events. The methodology is based on the development of a high resolution (1/12°) long-term (1958 - 2008) numerical simulation of the South-Atlantic Ocean using the Regional Ocean Modeling System (ROMS). The evaluation of the model performances show that the model is skilful in reproducing the mean state and the interannual variability. The evaluation of the equatorial forcing reveals a low-frequency modulation of the EKW activity with a significant reduction of the EKW energy from 1958 to 1990, then re-energized up to 2008. Variations are associated with change in EKW baroclinic mode contribution to interannual sea level anomalies: from 1958 the second baroclinic mode dominate, and is then balance by the third baroclinic mode after the late 1990's. Concomitantly, further analyses show a decrease of the wind stress forcing and a modulation of the magnitude of wind projection coefficients according to the oceanic baroclinic modes in the Guinea gulf with in particular a strong increase of the third EKW mode. Changes are associated with the increase (decrease) of the intensity (maximum depth) of the equatorial stratification. Our results suggest that the change in the remote equatorial forcing may play an important role in the modulation of the variability off the coasts of South-West Africa. These results will be confronted to the low frequency modulation of local wind variations and Coastal Trapped Waves (CTW) signature due to different stratification state along the south-eastern coast of ... |
author2 |
Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS) Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3) Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP) Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS) Brehmer, Patrice (ed.) Diogoul, N. (collab.) Ekau, W. (collab.) Mbaye, A. (collab.) Fall. A. (collab.) Monteiro, I. (collab.) Kouassi, A.M. (collab.) Silva, O. (collab.) Brochier, Timothée (collab.) Sall. M. (collab.) Mayif, M. (collab.) Koné, V. (collab.) Zenk, C. (collab.) Gorgues, Thomas (collab.) Ferreira Santos, C. (collab.) Bamy, I.L. (collab.) Barry, I. (collab.) Sidibe, M. (collab.) Diadhou, H. (collab.) Vareilles, M. de (collab.) Keenlyside, N. (collab.) Nascimento, J.M. (collab.) Ramos, V. M. (collab.) Sow, B.A. (collab.) Fock, H. (collab.) Schmidt, J. (collab.) |
format |
Conference Object |
author |
Bachelery, M.L. Illig, Serena Rouault, M. |
author_facet |
Bachelery, M.L. Illig, Serena Rouault, M. |
author_sort |
Bachelery, M.L. |
title |
How does the low-frequency Equatorial Kelvin Wave activity, local ocean stratification, and coastal winds modulate the south-eastern interannual Atlantic variability ? [résumé] |
title_short |
How does the low-frequency Equatorial Kelvin Wave activity, local ocean stratification, and coastal winds modulate the south-eastern interannual Atlantic variability ? [résumé] |
title_full |
How does the low-frequency Equatorial Kelvin Wave activity, local ocean stratification, and coastal winds modulate the south-eastern interannual Atlantic variability ? [résumé] |
title_fullStr |
How does the low-frequency Equatorial Kelvin Wave activity, local ocean stratification, and coastal winds modulate the south-eastern interannual Atlantic variability ? [résumé] |
title_full_unstemmed |
How does the low-frequency Equatorial Kelvin Wave activity, local ocean stratification, and coastal winds modulate the south-eastern interannual Atlantic variability ? [résumé] |
title_sort |
how does the low-frequency equatorial kelvin wave activity, local ocean stratification, and coastal winds modulate the south-eastern interannual atlantic variability ? [résumé] |
publisher |
HAL CCSD |
publishDate |
2018 |
url |
https://hal.science/hal-02777723 |
op_coverage |
Lanzarote, Spain |
genre |
South Atlantic Ocean |
genre_facet |
South Atlantic Ocean |
op_source |
ICAWA : International Conference AWA https://hal.science/hal-02777723 ICAWA : International Conference AWA, Apr 2018, Lanzarote, Spain. p. 63 |
op_relation |
hal-02777723 https://hal.science/hal-02777723 IRD: fdi:010078256 |
_version_ |
1766200509617668096 |
spelling |
ftunivnantes:oai:HAL:hal-02777723v1 2023-05-15T18:21:19+02:00 How does the low-frequency Equatorial Kelvin Wave activity, local ocean stratification, and coastal winds modulate the south-eastern interannual Atlantic variability ? [résumé] Bachelery, M.L. Illig, Serena Rouault, M. Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS) Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3) Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP) Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS) Brehmer, Patrice (ed.) Diogoul, N. (collab.) Ekau, W. (collab.) Mbaye, A. (collab.) Fall. A. (collab.) Monteiro, I. (collab.) Kouassi, A.M. (collab.) Silva, O. (collab.) Brochier, Timothée (collab.) Sall. M. (collab.) Mayif, M. (collab.) Koné, V. (collab.) Zenk, C. (collab.) Gorgues, Thomas (collab.) Ferreira Santos, C. (collab.) Bamy, I.L. (collab.) Barry, I. (collab.) Sidibe, M. (collab.) Diadhou, H. (collab.) Vareilles, M. de (collab.) Keenlyside, N. (collab.) Nascimento, J.M. (collab.) Ramos, V. M. (collab.) Sow, B.A. (collab.) Fock, H. (collab.) Schmidt, J. (collab.) Lanzarote, Spain 2018-04-17 https://hal.science/hal-02777723 en eng HAL CCSD SRFC/CSRP IRD hal-02777723 https://hal.science/hal-02777723 IRD: fdi:010078256 ICAWA : International Conference AWA https://hal.science/hal-02777723 ICAWA : International Conference AWA, Apr 2018, Lanzarote, Spain. p. 63 AFRIQUE SUBSAHARIENNE ANGOLA NAMIBIE ATLANTIQUE [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [SDE.MCG]Environmental Sciences/Global Changes info:eu-repo/semantics/conferenceObject Conference papers 2018 ftunivnantes 2023-02-22T05:35:18Z ICAWA : International Conference AWA, Lanzarote, ESP, 17-/04/2018 - 20/04/2018 The objective of this study is to describe the low-frequency modulation of the Equatorial Kelvin Wave (EKW) activity in the tropical Atlantic as well as the low-frequency modulation of the local stratification and coastal winds along the coast of south-western Africa. We aim at investigating the control of these forcings in modulating the oceanic interannual variability off the coasts of Angola/Namibia and the phenomenology of Benguela Niño/Niña events. The methodology is based on the development of a high resolution (1/12°) long-term (1958 - 2008) numerical simulation of the South-Atlantic Ocean using the Regional Ocean Modeling System (ROMS). The evaluation of the model performances show that the model is skilful in reproducing the mean state and the interannual variability. The evaluation of the equatorial forcing reveals a low-frequency modulation of the EKW activity with a significant reduction of the EKW energy from 1958 to 1990, then re-energized up to 2008. Variations are associated with change in EKW baroclinic mode contribution to interannual sea level anomalies: from 1958 the second baroclinic mode dominate, and is then balance by the third baroclinic mode after the late 1990's. Concomitantly, further analyses show a decrease of the wind stress forcing and a modulation of the magnitude of wind projection coefficients according to the oceanic baroclinic modes in the Guinea gulf with in particular a strong increase of the third EKW mode. Changes are associated with the increase (decrease) of the intensity (maximum depth) of the equatorial stratification. Our results suggest that the change in the remote equatorial forcing may play an important role in the modulation of the variability off the coasts of South-West Africa. These results will be confronted to the low frequency modulation of local wind variations and Coastal Trapped Waves (CTW) signature due to different stratification state along the south-eastern coast of ... Conference Object South Atlantic Ocean Université de Nantes: HAL-UNIV-NANTES |