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| Miramontes, Elda; Jorry, Stephan; Jouet, Gwenael; Counts, John; Courgeon, Simon; Roy, Philippe; Guerin, Charline; Hernández-molina, F. Javier. |
| Subaqueous sand dunes are common bedforms on continental shelves dominated by tidal and geostrophic currents. However, much less is known about sand dunes in deep‐marine settings that are affected by strong bottom currents. In this study, dune fields were identified on drowned isolated carbonate platforms in the Mozambique Channel (south‐west Indian Ocean). The acquired data include multibeam bathymetry, multi‐channel high‐resolution seismic reflection data, sea floor imagery, a sediment sample and current measurements from a moored current meter and hull‐mounted acoustic Doppler current profiler. The dunes are located at water depths ranging from 200 to 600 m on the slope terraces of a modern atoll (Bassas da India Atoll) and within small depressions... |
| Tipo: Text |
Palavras-chave: Bedform; Bottom currents; Contourite; Deep-marine environment; Eddy; Geostrophic current; Oceanic circulation. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00472/58418/60989.pdf |
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| Schulien, Jennifer A.; Della Penna, Alice; Gaube, Peter; Chase, Alison P.; Haëntjens, Nils; Graff, Jason R.; Hair, Johnathan W.; Hostetler, Chris A.; Scarino, Amy Jo; Boss, Emmanuel S.; Karp-boss, Lee; Behrenfeld, Michael J.. |
| Changes in airborne high spectral resolution lidar (HSRL) measurements of scattering, depolarization, and attenuation coincided with a shift in phytoplankton community composition across an anticyclonic eddy in the North Atlantic. We normalized the total depolarization ratio (δ) by the particulate backscattering coefficient (bbp) to account for the covariance in δ and bbp that has been attributed to multiple scattering. A 15% increase in δ/bbp inside the eddy coincided with decreased phytoplankton biomass and a shift to smaller and more elongated phytoplankton cells. Taxonomic changes (reduced dinoflagellate relative abundance inside the eddy) were also observed. The δ signal is thus potentially most sensitive to changes in phytoplankton shape because... |
| Tipo: Text |
Palavras-chave: HSRL; Depolarization; Backscatter; Phytoplankton community composition; Eddy. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00641/75313/75809.pdf |
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| De Marez, Charly; Meunier, Thomas; Morvan, Mathieu; L’hégaret, Pierre; Carton, Xavier. |
| We investigate the stability of a composite cyclone representative of Arabian Sea eddies using a high resolution primitive equation model. We observe that the eddy is unstable with respect to a mixed barotropic/baroclinic instability, leading to the growth of an azimuthal mode 2 perturbation. The latter deforms the eddy, which eventually evolves into a tripole after about 4 months of simulation. The presence of a critical level for the most unstable mode generates sharp fronts in the surface mixed layer where the Rossby number is large. These fronts then become unstable, and this generates submesoscale cyclones and filaments. Near these fronts, diapycnal mixing occurs, causing the potential vorticity to change sign locally, and symmetric instability to... |
| Tipo: Text |
Palavras-chave: Mesoscale; Eddy; Instability; Submesoscale; Vortex. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00598/70967/69196.pdf |
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| Hagen, E; Zulicke, C; Feistel, R. |
| A meso-scale CTD survey was conducted off Cape Ghir (31 degrees N) from 29 September to 3 October 1992, with the inspection of mass-field structures in the 300 dbar layer as its main objective, and relatively large tongue of cold surface water as the subject of investigation. This filament of upwelled water extends about 200 km seaward from the coastal zone of Morocco. Our CTD survey included two zonal transects 213 km in length, sampled synchronously by R/Vs Hudson along 31 degrees 30' N and A. v.Humboldt along 30 degrees 30' N. A meridional section followed the shelf edge at 10 degrees 10' W, and five zigzag sections were carried out above the Cape Ghir Plateau (CGP). Data resulting from an extended transect, sampled ten days earlier between 9 degrees... |
| Tipo: Text |
Palavras-chave: Coastal upwelling; Filament; Northwest Africa; Water mass; Eddy. |
| Ano: 1996 |
URL: http://archimer.ifremer.fr/doc/00096/20728/18365.pdf |
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