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| Dencausse, Guillaume; Arhan, Michel; Speich, Sabrina. |
| Using weekly sea surface height data Agulhas rings from the period October 1992 to December 2006 are detected and tracked from their formation dates and throughout the Cape Basin While 102 of them formed at the Agulhas Current retroflection their subsequent subdivisions and junctions led to 199 trajectories The rings geographical probability of presence shows two maxima One related to numerous ring passages lies in the submarine bight formed by the Erica seamount the Schmitt-Ott seamount and the northeastern tip of the Agulhas Ridge The other one to be ascribed to topographic blocking of the eddies is southeast of the latter obstacle On the basis of topographic effects three routes for Agulhas rings are distinguished a Northern route for rings that enter... |
| Tipo: Text |
Palavras-chave: Agulhas rings; Indo Atlantic exchanges; Altimetry. |
| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00019/13041/11315.pdf |
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| Arhan, Michel; Speich, Sabrina; Messager, Christophe; Dencausse, Guillaume; Fine, Rana; Boye, Marie. |
| Two eddies, one anticyclonic and the other cyclonic, intersected in the Subantarctic Zone south of South Africa during a hydrographic transect, are described using a large set of measurements including full depth hydrography, Acoustic Doppler Current Profiler velocities, biogeochemical tracers, air-sea fluxes and altimetric sea surface height. Both eddies have a subtropical origin. The anticyclone is an Agulhas ring with convected core water of similar to 12 degrees C, and swirl velocities of 1 m s(-1). It was 9.5 months old when sampled and had crossed the Agulhas Ridge. Though sampled in summer, it was releasing similar to 200 W m(-2) (sensible plus latent heat flux) to the atmosphere. It was observed adjacent to the Subantarctic Front, illustrating the... |
| Tipo: Text |
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| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00051/16220/13745.pdf |
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| Dencausse, Guillaume; Arhan, Michel; Speich, Sabrina. |
| A 14.3 year series of weekly absolute sea surface height (SSH) and associated geostrophic velocities is used for a study of the subtropical-to-subantarctic frontal system in the region south of Africa. Detecting the fronts from surface velocity maxima confirms a two-stepped transition in both the southeastern Atlantic Ocean (the Northern and Southern Subtropical fronts (NSTF, SSTF)) and southwestern Indian Ocean (the Agulhas Front and SSTF), as proposed previously from hydrographic data. An additional front associated with westward flow north of the NSTF is indicative of a partial eastern closure of the South Atlantic subtropical gyre between 11°E and 17.5°E. The role of northwestward propagating Agulhas rings in connecting the two fronts explains the... |
| Tipo: Text |
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| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00030/14096/11323.pdf |
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| Rivière, Pascal; Jaud, Thomas; Siegelman, Lia; Klein, Patrice; Cotté, Cedric; Le Sommer, Julien; Dencausse, Guillaume; Guinet, Christophe. |
| Sub‐mesoscale fronts—with scales from 1 to 50 km are ubiquitous in satellite images of the world oceans. They are known to generate strong vertical velocities with significant impacts on biogeochemical fluxes and pelagic ecosystems. Here, we use a unique data set, combining high‐resolution behavioral and physical measurements, to determine the effects of sub‐mesoscale structures on the foraging behavior of 12 instrumented female southern elephant seals. These marine mammals make long voyages (several months over more than 2000 km), diving and feeding continuously in the Antarctic Circumpolar Current. Our results show that elephant seals change their foraging behavior when crossing sub‐mesoscale fronts: They forage more and at shallower depths inside... |
| Tipo: Text |
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| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00584/69636/67497.pdf |
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| Dencausse, Guillaume; Arhan, Michel; Speich, Sabrina. |
| A 12 7-year series of weekly absolute sea surface height (SSH) data in the region south of Africa is used for a statistical characterization of the location of the Agulhas Current retroflection and its variations at periods up to 2 years The highest probability of presence of the retroflection point is at similar to 39 5 S/ 18-20 E The longitudinal probability density is negatively skewed A sharp eastward decrease at 22 E is related to detachments of the Agulhas Current from the continental slope at this longitude The asymmetry in the central part of the distribution might reflect a westward increase of the zonal velocity of the retroflection point during its east-west pulsations The western tail of the distribution reveals larger residence times of the... |
| Tipo: Text |
Palavras-chave: Agulhas Current retroflection; Indo Atlantic exchanges; Altimetry; Spatio temporal variations. |
| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00019/13040/11314.pdf |
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