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A note on the direct injection of turbulence by breaking waves ArchiMer
Rascle, Nicolas; Chapron, Bertrand; Ardhuin, Fabrice; Soloviev, Alexander.
We investigate the turbulence induced by wave-breaking at the ocean surface. Two recent models use a mechanism of direct depth injection of turbulent kinetic energy (TKE) by breaking waves. Those models aim to reproduce the near-surface mean and turbulent properties, in particular the TKE dissipation rates. Of critical importance are the injection depth of each breaking wave and the size distribution of those breaking waves. The models by Sullivan et al. (2007) and by Kudryavtsev et al. (2008) have very different parameterizations, and those differences are reviewed here and compared to available observations. Using realistic parameterizations in these models leads to TKE injections too shallow to compare to observations, in particular for developed seas....
Tipo: Text Palavras-chave: Surface waves; Wave breaking; Wave-induced turbulence; Vertical mixing; Mixed layer; Ekman currents.
Ano: 2013 URL: http://archimer.ifremer.fr/doc/00155/26581/25476.pdf
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Contrasted turbulence intensities in the Indonesian Throughflow: a challenge for parameterizing energy dissipation rate ArchiMer
Bouruet-aubertot, Pascale; Cuypers, Yannis; Ferron, Bruno; Dausse, Denis; Menage, Olivier; Atmadipoera, Agus; Jaya, Indra.
Microstructure measurements were performed along two sections through the Halmahera Sea and the Ombai Strait and at a station in the deep Banda Sea. Contrasting dissipation rates (𝜖) and vertical eddy diffusivities (K z ) were obtained with depth-averaged ranges of ∼[9×10−10−10−5] W kg− 1 and of ∼[1×10−5−2×10−3] m2 s− 1, respectively. Similarly, turbulence intensity, I=ϵ/(νN2) with ν the kinematic viscosity and N the buoyancy frequency, was found to vary seven orders of magnitude with values up to 107. These large ranges of variations were correlated with the internal tide energy level, which highlights the contrast between regions close and far from internal tide generations. Finescale parameterizations of 𝜖 induced by the breaking of...
Tipo: Text Palavras-chave: Turbulence; Internal tides; Vertical mixing; Parameterization; Indonesian seas; Microstructure measurements.
Ano: 2018 URL: https://archimer.ifremer.fr/doc/00441/55240/56792.pdf
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Efectos de la radiación solar sobre el fitoplancton de aguas antárticas y subantárticas OceanDocs
Hernando, M.P..
The increments in the ultraviolet radiation B (RUVB, 280-320 nm) resultants of the destruction of the ozone layer affect diverse echo-physiologic aspects of the marine phytoplankton. On this study were compared the responses of phytoplankton from an ambient Sub-Antarctic (Channel Beagle, 54º 52´S, 68º 18´W) and another Antarctic (Potter Cove, 62º 14´S, 58º 38´W) to the ultraviolet radiation (RUV). The decrease of the photosynthesis on short term (hours) was observed in both places, however inhibition thresholds were present. In the Beagle Channel, these were for RUVB and ultraviolet radiation A (RUVA, 320-400 nm), respectively, 0,2 and 6,2 Wm-2 for communities with more than 70% diatoms and 0,45 and 14,2 Wm-2, respectively, for communities with more than...
Tipo: Theses and Dissertations Palavras-chave: Phytoplankton; Photosynthesis; Ultraviolet radiation; Vertical mixing; Taxonomy; Phytoplankton; Taxonomy; Photosynthesis; Ultraviolet radiation; Http://aims.fao.org/aos/agrovoc/c_13344; Http://aims.fao.org/aos/agrovoc/c_7631; Http://aims.fao.org/aos/agrovoc/c_5812; Http://aims.fao.org/aos/agrovoc/c_8046.
Ano: 2008 URL: http://hdl.handle.net/1834/2868
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Mixed Layer formation and restratification in presence of mesoscale and submesoscale turbulence ArchiMer
Couvelard, Xavier; Dumas, Franck; Garnier, Valerie; Ponte, Aurelien; Talandier, Claude; Treguier, Anne-marie.
Recent realistic high resolution modeling studies show a net increase of submesoscale activity in fall and winter when the mixed layer depth is at its maximum. This submesoscale activity increase is associated with a reduced deepening of the mixed layer. Both phenomena can be related to the development of mixed layer instabilities, which convert available potential energy into submesoscale eddy kinetic energy and contribute to a fast restratification by slumping the horizontal density gradient in the mixed layer. In the present work, the mixed layer formation and restratification was studied by uniformly cooling a fully turbulent zonal jet in a periodic channel at different resolutions, from eddy resolving (10 km) to submesoscale permitting (2 km). The...
Tipo: Text Palavras-chave: Barticlinic jet; Mixed layer instabilities; Restratification; Mixedlayer depth; Vertical mixing; NEMO.
Ano: 2015 URL: http://archimer.ifremer.fr/doc/00286/39714/38169.pdf
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Mixing parameterization: Impacts on rip currents and wave set-up ArchiMer
Bennis, Anne-claire; Dumas, Franck; Ardhuin, Fabrice; Blanke, Bruno.
Wave set-up is often underestimated by the models (e.g. Raubenheimer et al., 2001). Our paper discusses how the wave set-up may be changed by the inclusion of turbulent mixing in the bottom shear stress. The parameterization developed in Mellor (2002) for phase-averaged oscillatory boundary layer is used for this purpose. Two studies are carried out. The dependence of the parameterization on the vertical discretization and on the magnitude of the near-bottom wave orbital velocity is investigated. The function that distributes the turbulent terms over the vertical is modified, giving a good agreement with the average of the phase-resolved velocities, but an overestimation of the turbulent phase-resolved velocities. Applying that parameterization to simulate...
Tipo: Text Palavras-chave: Bottom friction; Vertical mixing; Wave set-up; Nearshore processes.
Ano: 2014 URL: http://archimer.ifremer.fr/doc/00188/29970/28482.pdf
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On the seasonal variations of salinity of the tropical Atlantic mixed layer ArchiMer
Camara, I.; Kolodziejczyk, Nicolas; Mignot, Juliette; Lazar, Alban; Gaye, Amadou T..
The physical processes controlling the mixed layer salinity (MLS) seasonal budget in the tropical Atlantic Ocean are investigated using a regional configuration of an ocean general circulation model. The analysis reveals that the MLS cycle is generally weak in comparison of individual physical processes entering in the budget because of strong compensation. In evaporative regions, around the surface salinity maxima, the ocean acts to freshen the mixed layer against the action of evaporation. Poleward of the southern SSS maxima, the freshening is ensured by geostrophic advection, the vertical salinity diffusion and, during winter, a dominant contribution of the convective entrainment. On the equatorward flanks of the SSS maxima, Ekman transport mainly...
Tipo: Text Palavras-chave: Salinity; Seasonal variation; Tropical Atlantic; Vertical mixing.
Ano: 2015 URL: https://archimer.ifremer.fr/doc/00624/73563/73200.pdf
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SAR observing large-scale nonlinear internal waves in the White Sea ArchiMer
Kozlov, Igor; Romanenkov, Dmitry; Zimin, Alexei; Chapron, Bertrand.
The compiled archive of synthetic aperture radar (SAR) images acquired by the Advanced SAR (ASAR) onboard the Envisat satellite over the White Sea during the extended summer periods (May-September) between 2007 and 2011, provides the first detailed analysis of 2-D patterns of internal waves (IWs) in the White Sea. Unambiguously, the primary region of IW activity is the southwestern (SW) Gorlo Strait (GS). LW packets emerging from this area are regularly observed to reach crest lengths up to 200 km, and also to propagate a few hundred kilometers from their origin. Model results confirm that large-scale IWs can be generated every tidal cycle and are able to cross the entire sea. As suggested, the source of these packets is governed by the intense dynamics of...
Tipo: Text Palavras-chave: SAR imaging; Nonlinear internal waves; The White Sea; Vertical mixing.
Ano: 2014 URL: http://archimer.ifremer.fr/doc/00195/30617/29216.pdf
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Simulating vertical mixing in a shelf-break region: addition of a shear instability model, accounting for the overall effect of internal tides, on top of a one-dimensional turbulence closure mixed layer model ArchiMer
Druon, Jean-noel; Langlois, G; Le Fevre, J.
A simple parameterization of eddy diffusivity is used to simulate the shear mixing from tidally induced internal waves generated in the continental slope region southwest of Brittany. Near the edge of the shelf, the seasonal thermocline oscillates under the forcing of the barotropic tide which propagates over the shelf break. A composite model is constructed to simulate the mixing of the upper ocean from both external (wind stress) and internal (internal waves) sources. A simple one-dimensional eddy kinetic energy model, which predicts the temperature profile from heat flux and wind stress inputs, is validated with respect to regional hydroelimatic conditions, then coupled with a two-layer model of non-linear internal waves, to simulate the mixing...
Tipo: Text Palavras-chave: 6 degrees W); Bay of Biscay (47 degrees N; ECWMF fluxes; Internal waves; Wind stress; Shelf break; Vertical mixing.
Ano: 2001 URL: http://archimer.ifremer.fr/doc/2001/publication-5295.pdf
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Spatial variability in autumnal equatorial upwelling intensity within the Gulf of Guinea as inferred from in situ measurements ArchiMer
Nubi, O. A.; Oyatola, O.o; Bonou, F.
In attempt to study the spatial differences in autumnal equatorial upwelling intensity relative to bio-productivity in the eastern equatorial Atlantic, oceanographic in situ data along regions 10°W, 0°E, 2.5°E and 6°E, collected in the Gulf of Guinea during autumn cruise carried out in September 2007 were analyzed. The surface mean values for temperature along 10°W, 0°E, 2.5°E and 6°E are 25.02, 26.15, 26.88 and 25.60°C, respectively. There was eastward weakening of the equatorial undercurrent from 10°W until its complete disappearance at 6°E. The highest concentration of nitrate recorded at the surface at 10°W was attributed to the shoaling pycnocline observed at this region. The surface mean values for nitrate along 10°W, 0°E, 2.5°E and 6°E are 0.37,...
Tipo: Text Palavras-chave: Vertical mixing; Zonal advection; Equatorial undercurrent; Equatorial upwelling; Gulf of Guinea; Nutrients; Phytoplankton biomass; Surface enrichment..
Ano: 2019 URL: https://archimer.ifremer.fr/doc/00621/73318/72485.pdf
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Thermal structure of the Poraquê lake, Central Amazonian, Brazil - doi: 10.4025/actascibiolsci.v33i2.5150 Biological Sciences
Aprile, Fabio Marques; Laboratório Max Planck - INPA.
Thermal gradient of a Central Amazonian lake was studied to establish a link between seasonal variations in the water level, temperature, suspended particulate matter (SPM) and thermal stratification. Bimonthly measurements of temperature and PAR radiation were made at 0.25 m intervals from the surface to bottom from February 2004 to July 2006. Daily occurs full vertical mixing of the water column, and classic thermal stratification was not observed in the period. The effect of the winds associated to flood-pulse and the penetrative convection, transported the turbulent kinetic energy (TKE) into the lake mixing the column of water. This phenomenon was more expressive in the rainfall seasons when is generally higher contributing to the circulation of the...
Tipo: Estudos morfológicos e físico-químicos Palavras-chave: 2.05.02.00-1 Stratification; Vertical mixing; Hydrological cycle; TKE; Tropical lake; Amazon floodplain Ecologia de Ecossistemas Stratification; Vertical mixing; Hydrological cycle; TKE; Tropical lake; Amazon floodplain.
Ano: 2011 URL: http://periodicos.uem.br/ojs/index.php/ActaSciBiolSci/article/view/5150
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