Evolution of an oceanic anticyclone in the lee of Madeira Island: In situ and remote sensing survey
Island wakes are areas of a strong eddy activity influencing the availability and transport of organic matter in the ocean which, in turn impact biological productivity. Despite this, eddy formation in the lee of North Atlantic tropical islands is scarcely documented, except for the Canary Islands....
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ftarchimer:oai:archimer.ifremer.fr:30846 2023-05-15T17:36:08+02:00 Evolution of an oceanic anticyclone in the lee of Madeira Island: In situ and remote sensing survey Caldeira, Rui M. A. Stegner, Alexandre Couvelard, Xavier Araujo, Isabel B. Testor, Pierre Lorenzo, Alvaro 2014-02 application/pdf https://archimer.ifremer.fr/doc/00197/30846/29209.pdf https://doi.org/10.1002/2013JC009493 https://archimer.ifremer.fr/doc/00197/30846/ eng eng Amer Geophysical Union https://archimer.ifremer.fr/doc/00197/30846/29209.pdf doi:10.1002/2013JC009493 https://archimer.ifremer.fr/doc/00197/30846/ 2014. American Geophysical Union. All Rights Reserved info:eu-repo/semantics/openAccess restricted use Journal Of Geophysical Research-oceans (0148-0027) (Amer Geophysical Union), 2014-02 , Vol. 119 , N. 2 , P. 1195-1216 boundary-layer inertial instability mode water mixed layer intrathermocline eddies wake text Publication info:eu-repo/semantics/article 2014 ftarchimer https://doi.org/10.1002/2013JC009493 2021-09-23T20:24:41Z Island wakes are areas of a strong eddy activity influencing the availability and transport of organic matter in the ocean which, in turn impact biological productivity. Despite this, eddy formation in the lee of North Atlantic tropical islands is scarcely documented, except for the Canary Islands. Moreover, the occurrence of anticyclones leeward of Madeira has seldom been detected. During the summer of 2011, a multiplatform approach, combining satellite data with in situ measurements, was used to study an anticyclonic eddy generated in the lee of the Madeira Island. The main objective was to confirm recent numerical evidence suggesting that orographically perturbed winds can induce anticyclonic eddies leeward of Madeira, particularly during summer months. The high resolution sampling of the eddy's interior shows a strong downwelling of approximate to 100 m of the isopycnal layer below the mixed layer, typical of intrathermocline eddies. The 25 km radius of this anticyclonic structure exceeds the local deformation radius by a factor of 2. The vortex Rossby number remained moderate (Ro=0.26) even if the relative core vorticity reached a finite value (zeta/f = -0.7). The occurrence of strong trade winds (10-15 m s(-1)) prior to the detection of the first surface eddy signatures (July 2011) concurrent with opposite flowing geostrophic currents, shows that the orographic wind forcing is the main mechanism for generating this mesoscale long-lived eddy. After leaving the shelter of the island, the eddy traveled northwesterly following a perpendicular net Ekman transport pathway at a speed of 5 km/d, for at least 2 months. An interaction with a cyclonic partner generated in the area helped precipitate the northward trajectory. This study presents the first clear evidence of a wind-induced mesoscale anticyclone in the lee of Madeira. Article in Journal/Newspaper North Atlantic Archimer (Archive Institutionnelle de l'Ifremer - Institut français de recherche pour l'exploitation de la mer) Journal of Geophysical Research: Oceans 119 2 1195 1216 |
institution |
Open Polar |
collection |
Archimer (Archive Institutionnelle de l'Ifremer - Institut français de recherche pour l'exploitation de la mer) |
op_collection_id |
ftarchimer |
language |
English |
topic |
boundary-layer inertial instability mode water mixed layer intrathermocline eddies wake |
spellingShingle |
boundary-layer inertial instability mode water mixed layer intrathermocline eddies wake Caldeira, Rui M. A. Stegner, Alexandre Couvelard, Xavier Araujo, Isabel B. Testor, Pierre Lorenzo, Alvaro Evolution of an oceanic anticyclone in the lee of Madeira Island: In situ and remote sensing survey |
topic_facet |
boundary-layer inertial instability mode water mixed layer intrathermocline eddies wake |
description |
Island wakes are areas of a strong eddy activity influencing the availability and transport of organic matter in the ocean which, in turn impact biological productivity. Despite this, eddy formation in the lee of North Atlantic tropical islands is scarcely documented, except for the Canary Islands. Moreover, the occurrence of anticyclones leeward of Madeira has seldom been detected. During the summer of 2011, a multiplatform approach, combining satellite data with in situ measurements, was used to study an anticyclonic eddy generated in the lee of the Madeira Island. The main objective was to confirm recent numerical evidence suggesting that orographically perturbed winds can induce anticyclonic eddies leeward of Madeira, particularly during summer months. The high resolution sampling of the eddy's interior shows a strong downwelling of approximate to 100 m of the isopycnal layer below the mixed layer, typical of intrathermocline eddies. The 25 km radius of this anticyclonic structure exceeds the local deformation radius by a factor of 2. The vortex Rossby number remained moderate (Ro=0.26) even if the relative core vorticity reached a finite value (zeta/f = -0.7). The occurrence of strong trade winds (10-15 m s(-1)) prior to the detection of the first surface eddy signatures (July 2011) concurrent with opposite flowing geostrophic currents, shows that the orographic wind forcing is the main mechanism for generating this mesoscale long-lived eddy. After leaving the shelter of the island, the eddy traveled northwesterly following a perpendicular net Ekman transport pathway at a speed of 5 km/d, for at least 2 months. An interaction with a cyclonic partner generated in the area helped precipitate the northward trajectory. This study presents the first clear evidence of a wind-induced mesoscale anticyclone in the lee of Madeira. |
format |
Article in Journal/Newspaper |
author |
Caldeira, Rui M. A. Stegner, Alexandre Couvelard, Xavier Araujo, Isabel B. Testor, Pierre Lorenzo, Alvaro |
author_facet |
Caldeira, Rui M. A. Stegner, Alexandre Couvelard, Xavier Araujo, Isabel B. Testor, Pierre Lorenzo, Alvaro |
author_sort |
Caldeira, Rui M. A. |
title |
Evolution of an oceanic anticyclone in the lee of Madeira Island: In situ and remote sensing survey |
title_short |
Evolution of an oceanic anticyclone in the lee of Madeira Island: In situ and remote sensing survey |
title_full |
Evolution of an oceanic anticyclone in the lee of Madeira Island: In situ and remote sensing survey |
title_fullStr |
Evolution of an oceanic anticyclone in the lee of Madeira Island: In situ and remote sensing survey |
title_full_unstemmed |
Evolution of an oceanic anticyclone in the lee of Madeira Island: In situ and remote sensing survey |
title_sort |
evolution of an oceanic anticyclone in the lee of madeira island: in situ and remote sensing survey |
publisher |
Amer Geophysical Union |
publishDate |
2014 |
url |
https://archimer.ifremer.fr/doc/00197/30846/29209.pdf https://doi.org/10.1002/2013JC009493 https://archimer.ifremer.fr/doc/00197/30846/ |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
Journal Of Geophysical Research-oceans (0148-0027) (Amer Geophysical Union), 2014-02 , Vol. 119 , N. 2 , P. 1195-1216 |
op_relation |
https://archimer.ifremer.fr/doc/00197/30846/29209.pdf doi:10.1002/2013JC009493 https://archimer.ifremer.fr/doc/00197/30846/ |
op_rights |
2014. American Geophysical Union. All Rights Reserved info:eu-repo/semantics/openAccess restricted use |
op_doi |
https://doi.org/10.1002/2013JC009493 |
container_title |
Journal of Geophysical Research: Oceans |
container_volume |
119 |
container_issue |
2 |
container_start_page |
1195 |
op_container_end_page |
1216 |
_version_ |
1766135518698930176 |