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| Vianello, Patrick; Ternon, Jean-francois; Demarcq, Herve; Herbette, Steven; Roberts, Michael J.. |
| This work is part of the MADRidge Project special issue which aims to describe pelagic ecosystems in the vicinity of three prominent shallow seamounts in the South West Indian Ocean: one here named MAD-Ridge (240 m below the surface) plus Walters Shoal (18 m) on the Madagascar Ridge, and La Pérouse (60 m) on the abyssal plain east of Madagascar. The three span latitudes 20°S and 33°S, some 1500 km. The study provides the background oceanography for the once-off, multidisciplinary snapshot cruise studies around the seamounts. As life on seamounts is determined by factors such as summit depth, proximity to the light layers of the ocean, and the ambient circulation, a first description of regional spatial-field climatologies (16–22 years) and monthly... |
| Tipo: Text |
Palavras-chave: South West Indian Ocean; Madagascar Ridge; Seamounts; Walters shoal; Sea surface temperature; Eddy kinetic energy; Mixed layer depth; Chlorophyll-a; Geostrophic currents. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00634/74581/74476.pdf |
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| Helber, Robert W.; Kara, A. Birol; Richman, James G.; Carnes, Michael R.; Barron, Charlie N.; Hurlburt, Harley E.; Boyer, Timothy. |
| We characterize the global ocean seasonal variability of the temperature versus salinity gradients in the transition layer just below the mixed layer using observations of conductivity temperature and depth and profiling float data from the National Ocean Data Center's World Ocean Data set. The balance of these gradients determines the temperature versus salinity control at the mixed layer depth (MLD). We define the MLD as the shallowest of the isothermal, isohaline, and isopycnal layer depths (ITLD, IHLD, and IPLD), each with a shared dependence on a 0.2 degrees C temperature offset. Data are gridded monthly using a variational technique that minimizes the squared analysis slope and data misfit. Surface layers of vertically uniform temperature, salinity,... |
| Tipo: Text |
Palavras-chave: Density compensation; Mixed layer depth; Transition layer. |
| Ano: 2012 |
URL: https://archimer.ifremer.fr/doc/00383/49452/49917.pdf |
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| Dossa, A. N.; Da-allada, C. Y.; Herbert, G; Bourles, Bernard. |
| The region located in the far northeast of the Gulf of Guinea (NEGG), eastern tropical Atlantic, remains poorly documented due to a lack of available in situ ocean data. Heavy rainfall and intense river discharges observed in this region induce a strong salinity stratification that may have a significant impact on the mixed layer depth and on sea surface temperatures, through the so-called barrier-layer effect. By using recent in situ data and climatological outputs from a numerical simulation, we reveal the existence of a barrier layer in the NEGG and describe its seasonal occurrence. In the NEGG, the barrier layer limits the mixed layer depth. From January to March, significant values for the barrier-layer thickness are observed mostly due to the... |
| Tipo: Text |
Palavras-chave: Mixed layer depth; Niger River discharge; Numerical model; Oceanography; Sea surface salinity; Tropical Atlantic; Vertical stratification. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00509/62103/66273.pdf |
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