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| Menkes, Christophe; Kennan, Sc; Flament, Pierre; Dandonneau, Y; Masson, S; Biessy, B; Marchal, E; Eldin, G; Grelet, J; Montel, Y; Morliere, A; Lebourges-dhaussy, A; Moulin, C; Champalbert, G; Herbland, Alain. |
| [1] The equatorial Pacific and Atlantic oceans exhibit remarkable meridional undulations in temperature and chlorophyll fronts visible from space over thousands of kilometers and often referred to as tropical instability waves. Here, we present new observations of an ecosystem ranging through three trophic levels: phytoplankton, zooplankton and small pelagic fish whirling within a tropical vortex of the Atlantic ocean and associated with such undulations. Cold, nutrient and biologically rich equatorial waters are advected northward and downward to form sharp fronts visible in all tracers and trophic levels. The equatorward recirculation experiences upwelling at depth, with the pycnocline and ecosystem progressively moving toward the surface to reconnect... |
| Tipo: Text |
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| Ano: 2002 |
URL: http://archimer.ifremer.fr/doc/00000/10049/9584.pdf |
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| Marchal, E; Gerlotto, F; Stequert, B. |
| A migrating Sound Scattering Layer (SSL) was observed in the Eastern Atlantic equatorial system during warm and cool seasons. Averaged column scattering strength was nearly the same during daytime at 350-400 m depth and during night-time close to the surface. The depth of the nocturnal SSL was correlated with the depth of the thermocline. In the warm stable season, the maximum column scattering strength was found south of the equator in a dome shaped structure. In the cool season, the maximum was found at the northern convergence where the thermocline was well-marked, whereas upwelled waters were acoustically poor. For the warm season, this pattern is consistent with the distribution of chlorophyll, zooplankton and micronekton. For the cool season, it fits... |
| Tipo: Text |
Palavras-chave: SCATTERING LAYERS; EQUATORIAL DYNAMICS; TUNA FISHERIES. |
| Ano: 1993 |
URL: http://archimer.ifremer.fr/doc/00099/21053/18679.pdf |
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