Tracer distributions and deep circulation in the western tropical Atlantic during CITHER 1 and ETAMBOT cruises, 1993-1996
| Autor: | J.-F. Ternon, Bernard Bourlès, Chantal Andrié, Yves Gouriou, Claude Oudot |
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| Jazyk: | angličtina |
| Rok vydání: | 1999 |
| Předmět: |
BASSIN OCEANIQUE
Atmospheric Science SALINITE VARIATION SAISONNIERE SILICATE OXYGENE DISSOUS Soil Science Zonal and meridional Aquatic Science Tropical Atlantic Oceanography DYNAMIQUE DE L'EAU Geochemistry and Petrology TRACER Earth and Planetary Sciences (miscellaneous) TRACEUR OCEANIQUE Transect DISTRIBUTION SPATIALE TEMPERATURE World Ocean Circulation Experiment Earth-Surface Processes Water Science and Technology ANALYSE PHYSICOCHIMIQUE geography geography.geographical_feature_category Ecology Continental shelf North Atlantic Deep Water Paleontology Forestry CIRCULATION PROFONDE COMPOSE ORGANOCHLORE TOPOGRAPHIE Boundary current MASSE D'EAU GAZ DISSOUS BATHYMETRIE Geophysics PROFIL VERTICAL Space and Planetary Science COURANT MARIN CORRELATION Geology |
| Popis: | This paper presents CFC and nontransient tracer observations in the western equatorial Atlantic Ocean on repeated sections along 7°30′N, the 35°W meridian, and a transect crossing the Ceara Rise. Three World Ocean Circulation Experiment cruises have been carried out in this area, in February-March 1993 (CITHER 1) and September-October 1995 and April-May 1996 (ETAMBOT 1 and 2). Together with the tracer data, the direct current measurements are used to deduce the circulation pathways. The data confirm the principal circulation features of the Upper North Atlantic Deep Water within the area. The Deep Western Boundary Current flows southward along the continental slope, while, adjacent to the DWBC, there is a northward flow corresponding to the DWBC recirculation whose origin appears variable. The largest variability is observed along the 35°W meridional section, where the DWBC bifurcates eastward north of 3°S but the eastward equatorial flow does not appear to be permanent. At the Middle North Atlantic Deep Water level, CFC distributions exhibit the most important contrast between waters of northern and southern origin. The circulation at the Lower North Atlantic Deep Water level, mainly controlled by the topography, looks more permanent because the DWBC is regularly observed during the three cruises, and there is no evidence for a northwestward recirculation along the Mid-Atlantic Ridge. The transient behavior of CFC distributions, which is superimposed on local circulation effects, can be seen clearly through their temporal evolution within the DWBC. The variability of the deep circulation observed during the 1993–1996 interval rules out a dominant variability in response to semi annual forcing. |
| Databáze: | OpenAIRE |
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