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Registros recuperados: 28 | |
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Weatherly, G; Arhan, Michel; Mercier, Herle; Smethie, W. |
[1] We report evidence of two deep cyclonic and two deep anticyclonic submesoscale eddies from World Oceanographic Circulation Experiment hydrographic casts made in the Brazil Basin. We infer that three of these were likely formed in or near the Deep Western Boundary Current (DWBC) of North Atlantic Deep Water (NADW), and thus had traveled eastward after formation. These eddies appear to be a new way for transporting NADW away from the DWBC to the ocean interior. One of the apparent cyclonic eddies appeared to be laterally in contact with one of the anticyclonic eddies. About 10 days later an attempt was made to resample the apparent eddies that had been in contact. These observations, although limited, are interpreted to indicate that they survived the... |
Tipo: Text |
Palavras-chave: Eddies; Deep Western Boundary Current; Eddy merging. |
Ano: 2002 |
URL: https://archimer.ifremer.fr/doc/00000/10051/7796.pdf |
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Arhan, Michel; Carton, Xavier; Piola, A; Zenk, W. |
[1] Three deep anticyclonic eddies of a species only reported once before [Gordon and Greengrove, 1986] were intersected by hydrographic lines of the World Ocean Circulation Experiment (WOCE) and South Atlantic Ventilation Experiment (SAVE) programs in the Argentine Basin. The vortices are centered near 3500 m depth at the interface between North Atlantic Deep Water and Bottom Water. They have similar to1500-m-thick cores containing Lower Circumpolar Deep Water and a dynamical influence that may span up to two thirds of the water column. As one eddy was observed just downstream of the western termination of the Falkland Escarpment, a destabilization of the deep boundary current by the sudden slope relaxation is suggested as a potential cause of eddy... |
Tipo: Text |
Palavras-chave: Eddies and mesoscale processes; Western boundary currents; Hydrography. |
Ano: 2002 |
URL: https://archimer.ifremer.fr/doc/00000/10057/7797.pdf |
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Wienders, Nicolas; Arhan, Michel; Mercier, Herle. |
Data from a hydrographic section carried out in January-March 1994 offshore from the eastern coast of South America from 50S to 10N, are used to quantify the full-depth exchanges of water between the western boundary currents and the ocean interior. In the upper and intermediate layers, the westward transport associated with the southern branch of the South Equatorial Current was 49 Sv at the time of the cruise. The transports of the central and northern branches in the upper 200 m were 17 Sv and 12 Sv, respectively. After subtraction of the parts that recirculate in the subtropical, subequatorial, and equatorial domains, the fraction of the South Equatorial Current that effectively contributes to the warm water export to the North Atlantic is estimated at... |
Tipo: Text |
Palavras-chave: South equatorial Atlantic; Boundary current; Oceanic circulation. |
Ano: 2000 |
URL: https://archimer.ifremer.fr/doc/2000/publication-803.pdf |
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Blanke, Bruno; Arhan, Michel; Lazar, A; Prevost, Gwenaelle. |
The origins and fates of the Atlantic salinity maximum water (SMW), formed through excess evaporation in the tropics and subtropics of both hemispheres, are studied using monthly mean outputs of a numerical simulation of the world ocean climatological circulation. After defining formation domains from the surface salinity field and the vertical stratification, a Lagrangian technique is used to estimate the formation rates and main pathways in each hemisphere and the role of this water in the framework of the warm water return flow of the meridional overturning cell. Formation rates around 9 and 11 Sv are found in the Southern and Northern Hemispheres, respectively. While the export of the southern SMW from its formation area is realized by the western... |
Tipo: Text |
Palavras-chave: Atlantic ocean; Lagrangian method; Numerical simulation; Salinity; Sea water. |
Ano: 2002 |
URL: https://archimer.ifremer.fr/doc/2002/publication-769.pdf |
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Arhan, Michel; Billant, Andre; Branellec, Pierre; Mercier, Herle; Memery, Laurent; Messias, Marie-josé; Morin, Pascal; Wafar, Mohideen; Alvarez Salgado, Xosé; Aristegui, Javier; Gonzalez-davila, Melchor; Pazo Fernandez, Maria José; Rellan, Trinidad; Rios, Aida; Bingler, Linda; Groupe CITHER 3. |
De mi-janvier à début avril 1995 s'est déroulée la campagne CITHER 3 du programme WOCE-France, dans le but d'étudier les écoulements aux frontières méridiennes du bassin Atlantique Sud-Est: à l'ouest, les échanges avec les Bassins d'Argentine et du Brésil, et à l'est, les écoulements le long du talus continental Africain. Les paramètres hydrologiques et géochimiques requis par le Programme Hydrologique de WOCE (WHP) ont été mesurés de la surface au fond à 242 stations situées le long de deux radiales, l'une à 9° W entre le talus continental Ivoirien et la latitude 45° S, l'autre de Cape Town à la position 40° S - 10° E, puis au talus continental Ghanéen. Ce rapport, qui est le troisième volume de la série des recueils de données CITHER 3, présente les... |
Tipo: Text |
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Ano: 1998 |
URL: http://archimer.ifremer.fr/doc/00238/34920/33291.pdf |
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Memery, Laurent; Messias, Marie-josé; Arhan, Michel; Billant, Andre; Branellec, Pierre; Mercier, Herle; Alvarez Salgado, Xosé; Gonzales Castro, Carmen; Rios, Aida F.; Roson, Gabriel; Arlen, Linda; Bingler, Linda; Groupe CITHER 2. |
De janvier à Mars 1994 s'est déroulée la campagne CITHER 2 du programme WOCE-France, dans le but d'étudier les écoulements le long du bord Ouest de l'Océan Atlantique Sud. Les paramètres hydrologiques et géochimiques requis par le Programme Hydrologique de WOCE (WHP) ont été mesurés de la surface au fond, à 235 stations situées le long d'une radiale quasi-méridienne allant de 52° S à 10° N à environ 600 km du talus continental et, transversalement à cette radiale, le long de trois segments allant jusqu'au talus continental à environ 35° S, 13° S, et 10° N. Ce rapport, qui est le troisième volume de la série des recueils de données CITHER 2, présente les mesures des paramètres géochimiques mesurés sur prélèvements d'eau (salinité, oxygène dissous, sels... |
Tipo: Text |
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Ano: 1996 |
URL: http://archimer.ifremer.fr/doc/00238/34907/33185.pdf |
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Arhan, Michel; Colin De Verdiere, Alain; Memery, L. |
A quasi-meridional hydrographic section carried out between 60-degrees and 20-degrees-N offshore from the European and African continental slopes is analyzed in terms of water masses and zonal transports in and out of the eastern boundary. Outstanding features of the meridional distribution of water masses are focused on, such as the transition between North Atlantic and South Atlantic Central Waters at 20-degrees-25-degrees-N, the properties and anticyclonic circulation of the Rockall Channel mode water, and the northern boundary of the large-scale Mediterranean Water plume at about 50-degrees-N. An eastward transport of about 11 X 10(6) m3 s-1 is found to enter the eastern boundary layer at densities lower than 27.25 and feed southward alongshore... |
Tipo: Text |
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Ano: 1994 |
URL: http://archimer.ifremer.fr/doc/00196/30717/29449.pdf |
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Arhan, Michel; Plaisted, Ro. |
The present paper is a study of the nonlinear deformations of sea-wave profiles in intermediate (20 m depth) and shallow (4 m) water, based on wave staff and bottom pressure in situ measurements. The nonlinear deformations have been decomposed into two elementary classes : asymmetry with respect to the mean water surface and asymmetry with respect to a vertical line passed through the wave crest. The extend of the deformation of the first kind is estimated by computing the experimental statistical distributions of wave crest heights and through depths. These distributions are shown to deviate from the Rayleigh law (applicable to linear sea states), and are well fitted by a second order perturbation model deduced from the Stokes theory. The second kind of... |
Tipo: Text |
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Ano: 1981 |
URL: http://archimer.ifremer.fr/doc/1981/publication-5322.pdf |
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Gladyshev, S; Arhan, Michel; Sokov, A; Speich, Sabrina. |
The properties and circulation of water masses leaving and entering the Atlantic Ocean south of Africa are examined using data from a hydrographic and Lowered acoustic Doppler current profiler section from South Africa to the southern limit of the Antarctic Circumpolar Current (ACC). At the upper levels, the ACC fronts are well determined using either classical water mass definitions or gradient-based criteria. While the locations of the Subantarctic Front (SAF), Polar Front (PF), and Southern ACC Front (SACCF) seem controlled by the neighbouring ridges, that of the Subtropical Front (STF) is much influenced in this region (similar to 10 degrees E) by northwestward propagating Agulhas rings. No large amount of Subantarctic Mode Water (SAMW) is observed,... |
Tipo: Text |
Palavras-chave: Water masses; Fronts; Bottom circulation; Transport; Agulhas eddies; Antarctic Circumpolar Current. |
Ano: 2008 |
URL: http://archimer.ifremer.fr/doc/2008/publication-6097.pdf |
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Chever, Fanny; Bucciarelli, Eva; Sarthou, G.; Speich, Sabrina; Arhan, Michel; Penven, Pierrick; Tagliabue, A.. |
[1] Distributions of total dissolvable iron (TDFe; unfiltered), dissolved iron (DFe; 0.2 mu m filtered), and soluble iron (SFe; 0.02 mu m filtered) were investigated during the BONUS-GoodHope cruise in the Atlantic sector of the Southern Ocean (34 degrees S/17 degrees E-57 degrees S/0 degrees, February-March 2008). In the mixed layer, mean values of 0.43 +/- 0.28 and 0.22 +/- 0.18 nmol L-1 were measured for TDFe and DFe, respectively. In deeper waters, TDFe and DFe concentrations were 1.07 +/- 0.68 and 0.52 +/- 0.30 nmol L-1, respectively. DFe concentrations decreased from the north (subtropical waters) to the south (Weddell Sea Gyre). In the subtropical domain, dusts coming from Patagonia and southern Africa and inputs from the African continental margin... |
Tipo: Text |
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Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00017/12808/9763.pdf |
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Memery, Laurent; Arhan, Michel; Billant, Andre; Branellec, Pierre; Mercier, Herle; Groupe CITHER 2. |
De janvier à Mars 1994 s'est déroulée la campagne CITHER 2 du programme WOCE-France, dans le but d'étudier les écoulements le long du bord Ouest de l'Océan Atlantique Sud. Les paramètres hydrologiques et géochimiques requis par le Programme Hydrologique de WOCE (WHP) ont été mesurés de la surface au fond, à 235 stations situées le long d'une radiale quasi-méridienne allant de 52° S à 10° N à environ 600 km du talus continental et, transversalement à cette radiale, le long de trois segments allant jusqu'au talus continental à environ 35° S, 13° S, et 10° N. Ce rapport, qui est le deuxième volume de la série des recueils de données CITHER 2, présente les mesures des paramètres de la bathysonde (pression, température, salinité, et oxygène dissous). Les... |
Tipo: Text |
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Ano: 1995 |
URL: http://archimer.ifremer.fr/doc/00238/34906/33180.pdf |
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Mercier, Herle; Arhan, Michel; Lutjeharms, Johann. |
The upper-layer circulation in the eastern basin of the South Atlantic was studied from hydrographic and direct velocity measurements along WOCE lines A11, A13 and A14. A13 and A14 provide quasi-meridional samplings of the equatorial, subequatorial and subtropical circulation regimes. A13 was carried out along the African coast at about 600 km offshore from it, and A 14 along the nominal longitude 9degreesW. A11 intersects the Cape Basin between 46degreesS in the west and 30degreesS in the east. Transport estimates were derived from direct velocity measurements and a box inverse model. In the equatorial eastern Atlantic, the Equatorial Undercurrent (EUC) transport decreases from 25x10(6) m(3) s(-1) at 9degreesW to 13x10(6) m(3) s(-1) at 5degreesE.... |
Tipo: Text |
Palavras-chave: Hydrography; Current; Circulation; South Atlantic; Equatorial Atlantic. |
Ano: 2003 |
URL: https://archimer.ifremer.fr/doc/2003/publication-460.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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Faure, Vincent; Arhan, Michel; Speich, Sabrina; Gladyshev, Sergey. |
ARGO hydrographic profiles, two hydrographic transects and satellite measurements of air-sea exchange parameters were used to characterize the properties and seasonal heat budget variations of the Surface Mixed Layer (SML) south of Africa. The analysis distinguishes the Subtropical domain (STZ) and the Subantarctic Zone (SAZ), Polar Frontal Zone (PFZ) and Antarctic Zone (AZ) of the Antarctic Circumpolar Current. While no Subantarctic Mode Water forms in that region, occurrences of deep SML (up to similar to 450 m) are observed in the SAZ in anticyclones detached from the Agulhas Current retroflection or Agulhas Return Current. These are present latitudinally throughout the SAZ, but preferentially at longitudes 10-20A degrees E where, according to previous... |
Tipo: Text |
Palavras-chave: Ocean surface mixed layer; Heat budget; Southern Ocean; Agulhas Current retroflection. |
Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00048/15953/15833.pdf |
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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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Memery, Laurent; Arhan, Michel; Daniault, Nathalie; Hemon, Catherine; Mercier, Herle; Chipman, David W.; Groupe CITHER 2. |
De janvier à Mars 1994 s'est déroulée la campagne CITHER 2 du programme WOCE-France, dans le but d'étudier les écoulements le long du bord Ouest de l'Océan Atlantique Sud. Les paramètres hydrologiques et géochimiques requis par le Programme Hydrologique de WOCE (WHP) ont été mesurés de la surface au fond, à 235 stations situées le long d'une radiale quasi-méridienne allant de 52° S à 10° N à environ 600 km du talus continental et, transversalement à cette radiale, le long de trois segments allant jusqu'au talus continental à environ 35° S, 13° S, et 10° N. Ce rapport, qui est le premier des trois recueils de données CITHER 2, contient une brève description générale du programme CITHER et de la campagne CITHER 2, suivie d'une présentation des paramètres "en... |
Tipo: Text |
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Ano: 1996 |
URL: http://archimer.ifremer.fr/doc/00238/34905/33175.pdf |
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Registros recuperados: 28 | |
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