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| Bourles, B; D'Orgeville, Marc; Eldin, G; Gouriou, Y; Chuchla, R; Dupenhoat, Y; Arnault, S. |
| Eastward currents in the thermocline and subthermocline layers of the tropical Atlantic Ocean are described using observations obtained during two boreal summer cruises covering the whole equatorial basin. The analysis focuses on the eastward evolution of zonal currents in the thermocline and sub-thermocline. The Equatorial Undercurrent is not found close to the African coast in boreal summer 2000, maybe because of interannual variability. As observed in the Pacific, the South and North Equatorial Undercurrents are shown to shift poleward from west to east, and the two cruises indicate that the North Equatorial Undercurrent does not enter the Gulf of Guinea. The South and North Intermediate Countercurrents are variable with longitude and, contrarily to the... |
| Tipo: Text |
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| Ano: 2002 |
URL: http://archimer.ifremer.fr/doc/00000/10036/9583.pdf |
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| Arnault, S; Perigaud, C. |
| Tropical oceans play a key role in climatic variations. Ocean-atmosphere interactions induce large-scale and low-frequency variations which, due to the specificity of tropical ocean dynamics, are very difficult to observe with traditional in situ measurements. During the past twenty years, a variety of numerical models of diverse complexity have contributed much to the description, understanding and prediction of ocean variability in the tropics. However, the capacity of these models to simulate adequately the ocean variability heavily depends on the accuracy of the atmospheric forcings and that of initial conditions. Satellite altimetry provides a unique opportunity to avoid the problem of scarce and non-synoptic in situ data coverage for the large-scale... |
| Tipo: Text |
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| Ano: 1992 |
URL: http://archimer.ifremer.fr/doc/00100/21174/18791.pdf |
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| Bourles, B; Arnault, S; Provost, C. |
| We present results of sequential data assimilation of altimetric data in a linear tropical Atlantic model, using an analysis technique that we have developed. We use sea level anomaly fields obtained from altimetric data of the satellite Geosat. Despite the weak amplitudes of the anomaly fields, we obtain marked improvements of the model simulations due to assimilations. Thus, we show that altimetric data may be very useful for improving model simulations when adapted assimilation techniques are applied. |
| Tipo: Text |
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| Ano: 1992 |
URL: http://archimer.ifremer.fr/doc/00101/21179/18796.pdf |
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| Gouriou, Y; Andrie, C; Bourles, B; Freudenthal, S; Arnault, S; Aman, A; Eldin, G; Du Penhoat, Y; Baurand, F; Gallois, F; Chuchla, R. |
| In the Atlantic Ocean, the northward export of warm surface water is compensated by a southward flow of cold North Atlantic Deep Water (NADW). The NADW is transported southward along the American continental margin within the Deep Western Boundary Current (DWBC). Some tracer and float observations have shown that part of the DWBC water flows eastward along the equator. Here we present three meridional velocity sections which give an instantaneous image of the top-to-bottom zonal circulation along the equatorial Atlantic. They reveal the presence of Equatorial Deep Jets (EDJs) between 1 degrees 30'N and 1 degrees 30'S, alternating eastward-westward currents with short vertical scale, surrounded by columns of eastward currents (the Extra Equatorial Jets or... |
| Tipo: Text |
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| Ano: 2001 |
URL: http://archimer.ifremer.fr/doc/00000/10369/9567.pdf |
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| Gourdeau, L; Arnault, S; Menard, Y; Merle, J. |
| We present preliminary results on Geosat altimetric data assimilation in a linear vertical mode model of the tropical Atlantic Ocean. The Kalman filter technique is used to assimilate altimetric data along one track at a time as the satellite over-flies the basin. Sensitivity and validation tests have been performed with simulated data. The results obtained with Geosat data are presented and compared on a monthly basis with objective analysis of altimetric data and oceanic general circulation model results. |
| Tipo: Text |
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| Ano: 1992 |
URL: http://archimer.ifremer.fr/doc/00101/21181/18798.pdf |
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