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| Delpech, Audrey; Cravatte, S.; Marin, Frederic; Ménesguen, Claire; Morel, Y. |
| At the ocean surface, satellite observations have shown evidence of a large spectrum of waves at low latitudes. However, very little is known about the existence and properties of the deep variability. Most of the subsurface observations rely on localized measurements, which do not allow for a global estimation of this variability. In this study, we use velocity estimates, provided by Argo float drifts at 1,000 m, to analyze the spatial and temporal distribution of the deep eddy kinetic energy (EKE) and its spectral signature with an unprecedented time and space coverage. In the tropical Pacific, high EKE is found along the equator, at the western boundary and poleward of 7°N. EKE meridional distribution is also found to vary at the scale of the... |
| Tipo: Text |
Palavras-chave: Deep ocean; Equatorial and tropical ocean; Eddy kinetic energy; Equatorial waves; Argo floats. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00643/75483/76329.pdf |
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| Assene, Fernand; Morel, Yves; Delpech, Audrey; Aguedjou, Micael; Jouanno, Julien; Cravatte, Sophie; Marin, Frederic; Ménesguen, Claire; Chaigneau, Alexis; Dadou, Isabelle; Alory, Gael; Holmes, Ryan; Bourlès, Bernard; Koch-larrouy, Ariane. |
| In this paper, we analyse the results from a numerical model at high resolution. We focus on the formation and maintenance of subsurface equatorial currents in the Gulf of Guinea and we base our analysis on the evolution of potential vorticity (PV). We highlight the link between submesoscale processes (involving mixing, friction and filamentation), mesoscale vortices and the mean currents in the area. In the simulation, eastward currents, the South and North Equatorial Undercurrents (SEUC and NEUC respectively) and the Guinea Undercurrent (GUC), are shown to be linked to the westward currents located equatorward. We show that east of 20∘ W, both westward and eastward currents are associated with the spreading of PV tongues by mesoscale vortices. The... |
| Tipo: Text |
Palavras-chave: Equatorial atlantic; NEUC (North Equatorial Undercurrents); SEUC (South Equatorial Undercurrents); Vortices; Mixing; Friction. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00645/75697/76601.pdf |
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| Delpech, Audrey; Conchon, Anna; Titaud, Olivier; Lehodey, Patrick. |
| Micronekton – small marine pelagic organisms mostly in the size range 1–10 cm – is a key component of the ocean ecosystem, as it constitutes the main source of forage for all larger predators. Moreover, the mesopelagic component of micronekton that undergoes Diel Vertical Migration (DVM) likely plays a key role in the transfer and storage of CO2 in the deep ocean: the so-called ‘biological pump’ mechanism. SEAPODYM-MTL is a spatially explicit dynamical model of micronekton. It simulates six functional groups of migrant and non-migrant micronekton, in the epipelagic and mesopelagic layers. Coefficients of energy transfer efficiency between primary production and each group are unknown. But they are essential as they control the predicted biomass. Since... |
| Tipo: Text |
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| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00603/71463/69917.pdf |
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| Delpech, Audrey; Cravatte, Sophie; Marin, Frederic; Morel, Yves; Gronchi, Enzo; Kestenare, Elodie. |
| The mid-depth ocean circulation in the tropical Pacific is dominated by sets of alternating eastward and westward jets. The origin and transport properties of these flow features remain in many ways an open question, all the more crucial since their usual underestimation in ocean global circulation model has been identified as a potential bias for the misrepresentation of the oxygen minimum zones. In this study, we analyze the water mass properties associated with these systems of jets using velocity and hydrographic sections. Data acquired during a dedicated cruise carried out in the western part of the basin and supplemented by cross-equatorial sections from historical cruises in the central and eastern parts are analyzed. While it is confirmed that the... |
| Tipo: Text |
Palavras-chave: Pacific Ocean; Tropics; Jets. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00593/70490/68635.pdf |
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