![]() | Western boundary currents and transports off french-guiana as inferred from pegasus observations Auteur(s) : Colin, C Bourles, Bernard Éditeur(s) : Gauthier-Villars Résumé : Pegasus current measurements carried out along a section located off French Guiana are presented; the section was repeated five times from September 1989 to June 1991 during the NOE (region Nord-Ouest equatoriale)/STACS (Sub Tropical Atlantic Climate Studies) cruises on board the NOAA (National Oceanographic and Atmospheric Administration) research vessels. The data (vertical and horizontal distributions) show, as suggested by earliest observations, the presence of different currents. At the surface, and in winter, the North Brazil Current (NBC) flows northwestward (positive), is strong (120 cm/s), confined in the first 250 m, coastally trapped (within 250 km) and fed by offshore waters; in summer the NBC strengthens (the velocity increases to 150 cm/s), vertically extends (down to 800 m) and veers offshore; the mean NBC mass flux computed from all the sections available is 34 +/- 9 Sv with absolute maximum and minimum respectively in September 1989 (81 +/- 4 Sv) and February 1990 (13 +/- 1 Sv). Subsurface, a southeastward (negative) undercurrent (herein after named Western Boundary UnderCurrent) is present in winter-spring and located in the layer 250-800 m with similar velocities in February 1990 (- 33 cm/s) and June 1991 (- 29 cm/s) but with largest vertical and horizontal extensions in the latter case; in summer (September 1989 and September 1990) this undercurrent is absent; the mean mTBUC mass flux is - 9 +/- 3 Sv; the maximum is observed in June 1991 (- 19 +/- 2 Sv) and the minimum in February 1990 (- 3 +/- 0.4 Sv) and January 1991 (- 5 +/- I Sv). Deeper, the equatorward Deep Western Boundary Current is trapped against the continental shelf (within 100 km of the shelf break), extends downward from 1 200 to 3 000 m depth with the velocity core centred in the 1 700-2 000 m layer, is maximum (- 50 cm/s) in spring-summer and minimum (- 23 cm/s) in winter; the absolute velocity (- 92 cm/s) has been recorded at 2 000 m depth in September 1989 suggesting a strong variability at this level; the mean equatorward DWBC mass flux is - 30 +/- 14 Sv with absolute maximum and minimum respectively in September 1989 (- 59 +/- 6 Sv) and September 1990 (- 7 +/- 1 Sv). The Integrated Mass, Temperature and Salt Fluxes (IMF, ITF and ISF) with the cumulated errors, computed across the whole section and down to 3 000 m depth for the September 1990, January 1991 and June 1991 cruises, are all positive in September 1990 (respectively 1.9 +/- 19 Sv, 3.1 +/- 30.1 PW and 74 +/- 1 845 Tt/s) but all negative both in January 1991 (- 13.3 +/- 17.0 Sv, - 15.6 +/- 26.5 PW and - 478 +/- 1594 Tt/s) and June 1991 (- 3.8 +/- 10.1 Sv, - 4.0 +/- 16.3 PW, - 130 +/- 989 Tt/s) showing a strong variability between the summer and winter periods. The mean IMF, ITF and ISF values (respectively - 5.1 +/- 46.4 Sv, - 5.2 +/- 73 PW and - 178 +/- 4428 Tt/s) are high and negative, indicating the large influence of the DWBC and the associated North Atlantic Deep Water (upper part) off French Guiana at 5 degrees N. Oceanologica Acta (0399-1784) (Gauthier-Villars), 1994 , Vol. 17 , N. 2 , P. 143-157 Droits : info:eu-repo/semantics/openAccess http://archimer.ifremer.fr/doc/00098/20881/18495.pdf http://archimer.ifremer.fr/doc/00098/20881/ | Partager |
![]() | Algal growth on two sections of a fringing coral reef subject to different levels of eutrophication in Reunion Island Auteur(s) : Semple, S Éditeur(s) : Gauthier-Villars Résumé : The temporal Variations in macroalgal coverage and biomass of two sectors of a fringing reef complex in Reunion Island, subject to different levels of nutrient enrichment, were compared over eight months. Little difference was detected in the back reef zone, but in the narrow coral strip zone the highly enriched site showed significantly higher coverage, biomass and diversity of macroalgae throughout the whole study period. Differences in the levels of nutrient enrichment of the reef waters of the two sites are implicated as potential reasons for the observed differences. The seasonal Variations of macroalgae on the reef, and aspects of several of the dominant algal species encountered are also discussed. Oceanologica Acta (0399-1784) (Gauthier-Villars), 1997 , Vol. 20 , N. 6 , P. 851-861 Droits : info:eu-repo/semantics/openAccess http://archimer.ifremer.fr/doc/00093/20468/18140.pdf http://archimer.ifremer.fr/doc/00093/20468/ | Partager |
![]() | Environmental factors influencing asexual reproductive processes in echinoderms Auteur(s) : Mladenov, Pv Éditeur(s) : Gauthier-Villars Résumé : This review provides a brief update of the occurrence and adaptive significance of asexual reproduction in echinoderms. It then focuses on the state of knowledge of biotic and abiotic factors that influence asexual processes in this group, particularly factors that may play a role in regulating the expression and relative proportion of asexual versus sexual phenotypes within populations of species, as well as factors modulating and triggering asexual processes. The information presented in the review is synthesized into the form of a basic model depicting how environmental factors may interact with physiological factors to regulate asexual reproduction in echinoderms, and to show how such regulatory processes may parallel in some ways those known to regulate sexual reproduction. Since the model is based mainly on correlational evidence derived from comparative field observations, a number of experimental approaches for testing the predictions of the model are discussed briefly. Oceanologica Acta (0399-1784) (Gauthier-Villars), 1996 , Vol. 19 , N. 3-4 , P. 227-235 Droits : info:eu-repo/semantics/openAccess http://archimer.ifremer.fr/doc/00094/20481/18151.pdf http://archimer.ifremer.fr/doc/00094/20481/ | Partager |
![]() | Activité tectonique, magmatique et hydrothermale autour des triples jonctions de16°50'S-173°30'E et de l6°30'S-l76°10E dans le bassin nord fidjien (SWPacifique): Campagne HYFIFLUX Auteur(s) : Auzende, Jean-marie Halbach, P Allspach, A Becker, K Blum, N Bonnier, Olga Van Gerven, M Halbach, M Éditeur(s) : Gauthier-villars Résumé : The aim of the HYFIFLUX-SONNE 99 cruise was the geological, biological and chemical study of the 2 triple-junctions characterizing the oceanic accretion in the North Fiji Basin. Multibeam bathymetric coverage, in situ observations and sampling confirmed the existence of an active spreading ridge immediately west of the Fiji islands (WFR), and gave an evaluation of the magmatic and hydrothermal activity of the central ridge (CSR). New hydrothermal sites have been discovered and sampled. La campagne HYFIFLUX-SONNE 99 a eu pour objectif l'étude géologique, biologique et chimique des 2 triples jonctions qui caractérisent l'accrétion océanique dans le bassin nord fidjien. La couverture bathymétrique multifaisceaux, l'observation in situ et l'échantillonnage ont permis de confirmer l'existence d'un axe d'accrétion actif immédiatement à l'Ouest des îles Fidji (WFR), et d'évaluer l'activité magmatique et hydrothermale à l'extrémité nord de l'axe central (CSR). De nouveaux sites hydrothermaux ont été découverts et échantillonnés. Comptes Rendus de l'Academie des Sciences Serie II Fascicule A-Sciences de la Terre et des Planetes (Gauthier-villars), 1995-08 , Vol. 321 , N. 3 , P. 239-246 Droits : Académie des Sciences http://archimer.ifremer.fr/doc/00183/29453/27843.pdf http://archimer.ifremer.fr/doc/00183/29453/ | Partager Voir aussi SW Pacifique Dorsales Magmatisme Tectonique Hydrothermalisme. SW PACIFIC RIDGES MAGMATISM TECTONISM HYDROTHERMALISM Télécharger |
![]() | Subduction and Tectonics. Discussion on the Results of the IPOD Program in Active Margins Auteur(s) : Aubouin, J Blanchet, R Éditeur(s) : Gauthier-Villars Résumé : Since the advent of plate tectonics the active margins of the oceans have been studied according to a model whose basis is a piling up of imbrications of oceanic material units, in front of the upper plate, forming a great tectonic accretionary prism. This model is broadly the same for all the authors; it has been largely used for alpine-type or paleo-oceanic mountain chain, all around the world. The authors have directly taken part in the drillings on western and eastern Pacific active margins (Legs 60 and 67) and they have worked on the tectonics of alpine (paleo-oceanic) chains of the peri-mediterranean, peri-caribbean, and peripacific belts. They compare the geological data acumulated from these tow direct sources. The tectonic constraints constraints regime is specified and the consequences of the subduction are looked for. The notions of collison and obduction are discussed in relation to subduction and tectonics. Finally, an anlaysis of the temporal evolution of active margins and of chains, shows the necessity of thinking in terms of superimposed tectonics. Oceanologica Acta, Special issue (0399-1784) (Gauthier-Villars), 1981 Droits : info:eu-repo/semantics/openAccess http://archimer.ifremer.fr/doc/00246/35700/34207.pdf http://archimer.ifremer.fr/doc/00246/35700/ | Partager |
![]() | Traceurs organiques dans les dépôts de la vasière Ouest-Gironde (Golfe de Gascogne) Auteur(s) : Gadel, F Jouanneau, Jm Weber, O Serve, L Comellas, L Éditeur(s) : Gauthier-Villars Résumé : Mud fields located In the inner part of shelves in front of large estuaries are preferential environments for the investigation of the mechanisms and evolution in time of the supply of such sedimentary bodies. The study of different constituents of the particulate organic matter trapped in the sediments of the West Gironde mud patch contributes to the knowledge of the input origins. This study was carried out with different techniques, including pyrolysis-gas chromatography-mass spectrometry and high performance liquid chromatography, on samples from a core collected in the centre of the mud field. At the bottom of the core, the increase of sugars, amino-sugars and some aromatic hydrocarbons may indicate a more marine character of organic components. The same appears to be the case at the top of the core, where, despite a finer sedimentation, biochemical characteristics could show a more pronounced marine influence than in the middle part. In the middle part of the core, on the other hand, the increase in phenols could result from an increase in lignin-derived. terrestrial inputs. The increase in pyrolysis-derived cyclopentenone may indicate the same terrestrial influence, because this component has its origin in aliphatic polycarboxylic acids resulting from sail leaching. The continental character of the sedimentation is also reflected in the increase of the silt-clay fractions representative of suspended matter originating in the Gironde estuary, associated with a slight carbonate decrease. The taxonomic significance of some phenols is noteworthy: this is especially the case of the cinnamyls which, in the middle part of the core, emphasize the input of herbaceous debris and of the hydroxybenzyls which, at the bottom, provide evidence of the algal origin of part of the organic material. Thus, by means of pyrolysis results and HPLC phenol analysis, it is possible to establish the more or less continental signature of organic components trapped in the ''Ouest-Gironde'' mud patch. This study of organic matter, which confirms earlier sedimentological and micropaleontological data, constitutes a new approach, adapted to the identification of the origin of carbon sources. Oceanolica Acta (0399-1784) (Gauthier-Villars), 1997 , Vol. 20 , N. 5 , P. 687-695 Droits : info:eu-repo/semantics/openAccess http://archimer.ifremer.fr/doc/00093/20426/18093.pdf http://archimer.ifremer.fr/doc/00093/20426/ | Partager |
![]() | Structure et organisation de l'étang de Thau d'après la faune benthique (macrofaune, méiofaune). Relations avec le confinement Auteur(s) : Guelorget, O Perthuisot, Jp Lamy, N Lefebvre, A Éditeur(s) : Gauthier-Villars Résumé : The biogeological organization of Thau lagoon was investigated through the granulometric analysis of surficial sediments and study of the qualitative and the quantitative distribution of benthic macrofauna and meiofauna. These show clearly that the lagoonal system is organized according to confinement as conceived by Guelorget and Perthuisot (1983 a; 1992), which depends upon the rate of exchanges with the open sea and the hydrodynamic pattern of the basin. The latter appears to be composed of a pair of lagoonal subsystems separated by a hydrodynamically unstable barrier. The northern subsystem displays the classical concentric organization of Mediterranean lagoons with a clearly defined hydraulic umbilicus. The southern subsystem displays a transverse original organization due to a large zone of exchanges with the sea through the sand bar. The basin is globally subject to only slight confinement, but displays signs of organic matter accumulation due to the intensification of shellfish culture. Oceanologica Acta (0399-1784) (Gauthier-Villars), 1994 , Vol. 17 , N. 1 , P. 105-114 Droits : info:eu-repo/semantics/openAccess http://archimer.ifremer.fr/doc/00098/20880/18494.pdf http://archimer.ifremer.fr/doc/00098/20880/ | Partager |
![]() | Répartition des Noelaerhabdaceae (nannofossiles calcaires) dans le Quaternaire moyen et supérieur des océans Atlantique et Pacifique Auteur(s) : Pujos, A Giraudeau, J Éditeur(s) : Gauthier-Villars Résumé : Calcareous nannofossil assemblages of the family Noelaerhabdaceae have been studied in sediments of seventeen Quaternary cores raised from various climatic areas of the Atlantic and Pacific oceans. These sections display a regular, hiatus-free sedimentation for the last 500000 years. They have been dated using oxygen-isotopic measurements, variations of calcium carbonate content, variations of total nannofossil abundance, thorium measurements and volcanic ash horizons. Coccoliths of the genus Gephyrocapsa have been placed in three distinct taxonomic groups, based on morphological criteria inferred from light-microscope observations. Their acmes, as well as the acme of Emiliania huxleyi, are considered as stratigraphic markers. These markers characterize most of the last thirteen glacial-interglacial climatic stages, as well as some climatic events of lower magnitude (8.5 and 6.5). Most of these markers have global stratigraphic significance: acme of ''closed'' Gephyrocapsa during stages 13,11 and 9, and during event 8.5; acme of ''small'' Gephyrocapsa during stage 7 and event 6.5; acme of ''open'' Gephyrocapsa at top of event 6.5, and during stages 5 and 3; acme of E. huxleyi during stages 3 and 1. Others are only valid south of the southernmost latitude reached by the North-Atlantic polar front during the Quaternary: acme of ''closed'' Gephyrocapsa during stage 12; acme of ''small'' Gepkyrocapsa in early and middle stage 5; acme of E. huxleyi during stage 2. Others are only valid south of 20-degrees-S: acme of ''small'' Gephyrocapsa at the 10/9 stage boundary; acme of ''open'' Gephyrocapsa during stage 6. Oceanologica Acta (0399-1784) (Gauthier-Villars), 1993 , Vol. 16 , N. 4 , P. 349-362 Droits : info:eu-repo/semantics/openAccess http://archimer.ifremer.fr/doc/00099/21061/18687.pdf http://archimer.ifremer.fr/doc/00099/21061/ | Partager |
![]() | Nannoplankton and foraminifera biostratigraphy and microfacies of the Cretaceous to Cenozoic post-platform series (Mazagan Escarpment, Morocco) Auteur(s) : Cepek, P Hagn, H Éditeur(s) : Gauthier-Villars Résumé : The paper summarizes the biostratigraphic results of eighteen dives of the French submersible Cyana at the Mazagan Escarpment (CYAMAZ cruise), based on calcareous nannoplankton and foraminifera. This paper is restricted to the study of the Early Cretaceous to Quaternary post-platform series. Most of the stratigraphical data are based on the determination of calcareous nannofossils (P. Cepek) which, however, are mostly poorly preserved and of rare occurrence. From the 170 studied subsamples 49 are barren of calcareous samples are listed according to the species epithets, separated for the Cretaceous and Tertiary. The biostratigraphy based on foraminifera and the microfacies was studied in thin-section (H. hagn). Foraminiferal microfaunas of Late Cretaceous, Paleocene, Eocene-Oligocene and Quaternary age are described and shown in Plates. Oceanologica Acta, Special issue (0399-1784) (Gauthier-Villars), 1985 Droits : info:eu-repo/semantics/openAccess http://archimer.ifremer.fr/doc/00247/35827/34337.pdf http://archimer.ifremer.fr/doc/00247/35827/ | Partager |
![]() | Biomasse du mesozooplancton au large de la Guyane française Auteur(s) : Razouls, C Éditeur(s) : Gauthier-Villars Oceanologica Acta (0399-1784) (Gauthier-Villars), 1985 , Vol. 8 , N. 1 , P. 125-129 Droits : info:eu-repo/semantics/openAccess http://archimer.ifremer.fr/doc/00112/22297/19972.pdf http://archimer.ifremer.fr/doc/00112/22297/ | Partager |
![]() | ENSO signals in the vicinity of New Caledonia, South Western Pacific Auteur(s) : Delcroix, T Lenormand, O Éditeur(s) : Gauthier-Villars Résumé : Data collected in an area enclosing New Caledonia are analysed both for the open ocean (17 degrees S-27 degrees S, 169 degrees E-170 degrees E; 1972-1992) and for one point in its lagoon (1967-1993), in order to improve our knowledge of the regional environment, with emphasis on seasonal and interannual (i.e. ENSO) variability. Long-term means and seasonal changes in surface wind, sea-surface temperature and salinity, and 0-400 m temperature, salinity and zonal geostrophic current are first described to Set the context. Through comparisons with the Southern Oscillation Index (SOI), it is demonstrated that there are signals in these parameters that are connected with ENSO. During the warm phase of ENSO (SOI < 0, El Nino), we observed saltier-than-average anomalies in sea-surface salinity (similar to 0.2), 0-50 m cold temperature anomalies (similar to 0.5 degrees C) contrasting with the well-known warm eastern equatorial Pacific anomalies, together with westerly (similar to 10 m(2) s(-2)) and southerly (similar to 4 m(2) s-2) wind anomalies over a large part of the studied area. Conversely, anomalies of similar magnitude but of opposite sign were detected during the cold phase of ENSO (SOI > 0; La Nina). The mechanisms which connect these regional anomalies to ENSO evolution at low-latitudes are qualitatively discussed. Oceanolica Acta (0399-1784) (Gauthier-Villars), 1997 , Vol. 20 , N. 3 , P. 481-491 Droits : info:eu-repo/semantics/openAccess http://archimer.ifremer.fr/doc/00093/20410/18077.pdf http://archimer.ifremer.fr/doc/00093/20410/ | Partager |
![]() | Recyclage des sels nutritifs par le macroplancton-micronecton dans le Pacifique tropical Sud-Ouest Auteur(s) : Roger, C Éditeur(s) : Gauthier-Villars Oceanologica Acta (0399-1784) (Gauthier-Villars), 1988-01 , Vol. 11 , N. 1 , P. 107-116 Droits : info:eu-repo/semantics/openAccess http://archimer.ifremer.fr/doc/00108/21886/19477.pdf http://archimer.ifremer.fr/doc/00108/21886/ | Partager |
![]() | Le récif-barrière et le lagon du Grand Cul-de-Sac Marin (Guadeloupe, Antilles françaises). Géomorphologie et sédiments Auteur(s) : Guilcher, A Marec, A Éditeur(s) : Gauthier-Villars Oceanologica Acta (0399-1784) (Gauthier-Villars), 1978 , Vol. 1 , N. 4 , P. 435-444 Droits : info:eu-repo/semantics/openAccess http://archimer.ifremer.fr/doc/00123/23398/21225.pdf http://archimer.ifremer.fr/doc/00123/23398/ | Partager |
![]() | Aspects of the steroid geochemistry of an interfacial sediment from the peruvian upwelling Auteur(s) : Smith, Dj Eglinton, G Morris, Rj Poutanen, El Éditeur(s) : Gauthier-Villars Oceanologica Acta (0399-1784) (Gauthier-Villars), 1983 , Vol. 6 , N. 2 , P. 211-219 Droits : info:eu-repo/semantics/openAccess http://archimer.ifremer.fr/doc/00114/22476/20157.pdf http://archimer.ifremer.fr/doc/00114/22476/ | Partager |
![]() | Biogenic silica in the Bay of Bengal during the southwest monsoon Auteur(s) : Gupta, Gvm Sarma, Vv Éditeur(s) : Gauthier-Villars Résumé : During RV Gaveshani cruise No. 235 (August-September, 1993), particulate matter was collected from euphotic and deeper waters in the Bay of Bengal and analysed for biogenic silica (BSi), lithogenic silica (LSi) and particulate organic carbon (POC). Mean depth profiles of BSi showed a minimum in the surface waters and a maximum in the middle depths of the euphotic zone. The deepening of BSi maxima from north to south coincides with the deepening of the thermocline and thickening of the surface layer. In coastal waters, the contribution of BSi to total particulate silica was high (> 80 %); in offshore waters it was 60-70 %. BSi/POC (0.086) and LSi/POC (0.023) ratios show that particulate matter consists mostly of biogenic material, while the BSi/LSi (1.61) ratio revealed the dominance of siliceous phytoplankton in the euphotic zone. High concentrations of BSi (0.49 mu mol l(-1)) and LSi (1.89 mu mol l(-1)) in deeper waters are due to a high sedimentation rate, the resuspension of bottom sediments and the flow of large amounts of riverine siliceous material. Oceanologica Acta (0399-1784) (Gauthier-Villars), 1997 , Vol. 20 , N. 3 , P. 493-500 Droits : info:eu-repo/semantics/openAccess http://archimer.ifremer.fr/doc/00093/20459/18131.pdf http://archimer.ifremer.fr/doc/00093/20459/ | Partager |
![]() | On the variability of yellow substance in the skagerrak and the kattegat Auteur(s) : Karabashev, Gs Khanaev, Sa Kuleshov, Af Éditeur(s) : Gauthier-Villars Résumé : The variability of ''yellow substance'' in waters of the Skagerrak and the Kattegat was studied during the international Skagex programme in 1990 and 1991. Data on attenuation of light and fluorescence of dissolved organic matter (DOM) in sea water were collected with a spectral transmissiometer and a submersible fluorometer within a depth range of 0-250 m at several stations. More than fifty-fold variations of fluorescence intensity over space and time were due to the combined action of different sources of DOM in the straits. The surface maximum of fluorescing DOM, related to river outflow, was spreading from Oslo fjord to the central Skagerrak in late spring. This maximum may be ecologically important because it diminishes shortwave PAR. In the autumn the brightest DOM fluorescence was found in the Kattegat and along the Norwegian coast in accordance with earlier studies. The local minima of DOM fluorescence are associated with the Jutland current. Both the instability of the current and a ten-fold difference in DOM content between deep layers of the Skagerrak and Kattegat resulted in strong synoptic variability of fluorescence in the transitional area between the straits. Seasonal and synoptic variabilities of ''yellow substance'' were minimal in the southern Kattegat. The vertical gradients of DOM fluorescence were mostly negative at the depth of the thermocline of the open Skagerrak in spring, reaching values of 40-50 % m-1. Fine structure and complex shape were inherent to fluorescence profiles from areas of intensive water mixing. DOM fluorescence closely covaried with attenuation of UV light: the correlation coefficient was + 0.9 for wavelength w <= 350 nm regardless of season. The inverse dependence between wavelength derivative and magnitude of UV attenuation in the straits did not change with season. DOM fluorescence and water salinity were negatively correlated at depths of 25-50 m but they varied independently in the upper 10 m. No significant correlation between fluorescence and nitrates has been found. Estimates of correlation with phosphates ranged from 0.7 to 0.8. In general, the changes of fluorescence were due to variations of DOM content in sea water but not to variability of DOM composition or state. The properties of DOM fluorescence in the Skagerrak-Kattegat area make it a useful natural tracer of water movements suitable for active remote sensing with airborne lidar. Oceanologica Acta (0399-1784) (Gauthier-Villars), 1993 , Vol. 16 , N. 2 , P. 115-125 Droits : info:eu-repo/semantics/openAccess http://archimer.ifremer.fr/doc/00099/21041/18667.pdf http://archimer.ifremer.fr/doc/00099/21041/ | Partager |
![]() | Bioturbation récente au large de la Nouvelle-Calédonie. Premiers résultats de la campagne Biocal Auteur(s) : Gaillard, C Éditeur(s) : Gauthier-Villars Oceanologica Acta (0399-1784) (Gauthier-Villars), 1988-10 , Vol. 11 , N. 4 , P. 389-399 Droits : info:eu-repo/semantics/openAccess http://archimer.ifremer.fr/doc/00106/21768/19342.pdf http://archimer.ifremer.fr/doc/00106/21768/ | Partager |
![]() | Microheterotrophic utilization of dissolved free amino-acids in depth profiles of southern-california borderland basin waters Auteur(s) : Carlucci, Af Craven, Db Robertson, Kj Henrichs, Sm Éditeur(s) : Gauthier-Villars Oceanologica Acta (0399-1784) (Gauthier-Villars), 1986-01 , Vol. 9 , N. 1 , P. 89-96 Droits : info:eu-repo/semantics/openAccess http://archimer.ifremer.fr/doc/00112/22280/19955.pdf http://archimer.ifremer.fr/doc/00112/22280/ | Partager |
![]() | Western boundary current variability off french-guiana as observed from moored current measurements Auteur(s) : Colin, C Bourles, B Chuchla, R Dangu, F Éditeur(s) : Gauthier-Villars Résumé : Moored current measurements carried out from 31 March 1990 to 15 September 1991 in two stages at a point (near 6 degrees N) located over the mid-continental slope off French Guiana are presented. Six current meters were positioned between 200 and 2700 m depth. Upper level mean current data showed a northwestward flowing North Brazil Current (NBC) with mean velocity values decreasing from 10 cm/s in the range 200-250 m to almost zero at 800 m depth, the level of the Antarctic Intermediate Waters. In the range 500-800 m, the current reversed in spring in the presence of the southeastward Western Boundary Under Current (WBUC); the mean velocity from February to June 1991 is around 2 cm/s. Deep currents over the continental rise show a strong southeastward Deep Western Boundary Current extending from around 1000 m depth to the bottom (3000 m depth in this case) with mean core speeds of 20 cm/s at 2000-2070 m depth. Transport estimates based on these data and a few Pegasus sections for the mean vertical and lateral extensions of the DWBC yield a value of 21 x 10(6) m(3)/s at that location. Low-frequency current fluctuations were dominated by a well-defined 50- to 70-day period oscillation with peak-to-peak northwestward velocity amplitude of around 90 cm/s at the upper level. The mean vertical eddy kinetic energy distribution showed an abrupt decrease of the energy down to 800 m depth and a slight decrease below and down to the bottom. Oceanologica Acta (0399-1784) (Gauthier-Villars), 1994 , Vol. 17 , N. 4 , P. 345-354 Droits : info:eu-repo/semantics/openAccess http://archimer.ifremer.fr/doc/00098/20897/18510.pdf http://archimer.ifremer.fr/doc/00098/20897/ | Partager |
![]() | Temporal changes of aeolian saharan input in the cape verde abyssal-plain since the last glacial period Auteur(s) : Grousset, F Buatmenard, P Boust, D Tian, Rc Baudel, S Pujol, C Vergnaudgrazzini, C Éditeur(s) : Gauthier-Villars Oceanologica Acta (0399-1784) (Gauthier-Villars), 1989-04 , Vol. 12 , N. 2 , P. 177-185 Droits : info:eu-repo/semantics/openAccess http://archimer.ifremer.fr/doc/00131/24229/22222.pdf http://archimer.ifremer.fr/doc/00131/24229/ | Partager |