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Registros recuperados: 11
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On Growth Rate of Wind Waves: Impact of Short-Scale Breaking Modulations ArchiMer
Kudryavtsev, Vladimir; Chapron, Bertrand.
The wave generation model based on the rapid distortion concept significantly underestimates empirical values of the wave growth rate. As suggested before, inclusion of the aerodynamic roughness modulations effect on the amplitude of the slope-correlated surface pressure could potentially reconcile this model approach with observations. This study explores the role of short-scale breaking modulations to amplify the growth rate of modulating longer waves. As developed, airflow separations from modulated breaking waves result in strong modulations of the turbulent stress in the inner region of the modulating waves. In turn, this leads to amplifying the slope-correlated surface pressure anomalies. As evaluated, such a mechanism can be very efficient for...
Tipo: Text Palavras-chave: Atm; Ocean Structure; Phenomena; Atmosphere-ocean interaction.
Ano: 2016 URL: http://archimer.ifremer.fr/doc/00313/42414/41759.pdf
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Measurements of Enhanced Near-Surface Turbulence Under Windrows ArchiMer
Zippel, Seth F.; Maksym, Ted; Scully, Malcolm; Sutherland, Peter; Dumont, Dany.
Observations of waves, winds, turbulence, and the geometry and circulation of windrows were made in a shallow bay in the winter of 2018 outside of Rimouski, Québec. Water velocities measured from a forward-looking pulse-coherent ADCP mounted on a small zodiac show spanwise (cross-windrow) convergence, streamwise (downwind) velocity enhancement, and downwelling in the windrows, consistent with the view that windrows are the result of counter-rotating pairs of wind-aligned vortices. The spacing of windrows, measured with acoustic backscatter and with surface imagery, was measured to be approximately twice the water depth, which suggests an aspect ratio of 1. The magnitude and vertical distribution of turbulence measured from the ADCP are consistent with a...
Tipo: Text Palavras-chave: Ocean; Atmosphere-ocean interaction; Boundary layer; Langmuir circulation; In situ oceanic observations; Surface observations.
Ano: 2020 URL: https://archimer.ifremer.fr/doc/00593/70552/68722.pdf
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Heat balance in the Nordic Seas in a global 1/12° coupled model ArchiMer
Treguier, Anne-marie; Mathiot, Pierre; Graham, Tim; Copsey, Dan; Lique, Camille; Sterlin, Jean.
The Nordic Seas are a gateway to the Arctic Ocean, where Atlantic water undergoes a strong cooling during its transit. Here we investigate the heat balance of these regions in the high resolution Met Office Global Coupled Model GC3 with a 1/12_ grid. The GC3 model reproduces resolution Met Office Global Coupled Model GC3 with a 1/12_ grid. The GC3 model reproduces the contrasted ice conditions and ocean heat loss between the eastern and western regions of the Nordic Seas. In the west (Greenland and Iceland seas), the heat loss experienced by the ocean is stronger than the atmospheric heat gain, because of the cooling by ice melt. The latter is a major contribution to the heat loss over the path of the East Greenland Current and west of Svalbard. In the...
Tipo: Text Palavras-chave: Arctic; Atmosphere-ocean interaction; Ocean dynamics; Eddies; Climate models; Oceanic variability.
Ano: 2021 URL: https://archimer.ifremer.fr/doc/00654/76590/77739.pdf
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Sea Surface Salinity from French RESearcH Vessels : Delayed mode dataset, annual release ArchiMer
Gaillard, Fabienne; Diverres, Denis; Jacquin, Stéphane; Gouriou, Yves; Grelet, Jacques; Le Menn, Marc; Tassel, Joelle; Reverdin, Gilles.
French Research vessels have been collecting thermo-salinometer (TSG) data since the early 2000 in contribution to the GOSUD programme. The set of homogeneous instruments is permanently monitored and regularly calibrated. Water samples are taken on a daily basis by the crew and later analysed in the laboratory. We present here the delayed mode processing of the 2001-2013 dataset and an overview of the resulting quality. The careful calibration and instrument maintenance, complemented with a rigorous adjustment on water samples lead to reach an accuracy of a few 10-² PSS in salinity or evenless. Global comparison with the ISAS13 ARGO gridded product shows an excellent agreement of the datasets. The SSS-Fresh dataset appears as highly valuable for the...
Tipo: Dataset Palavras-chave: Sea surface salinity; Climate variability; Fresh water cycle; Atmosphere-ocean interaction.
Ano: 2015 URL: http://dx.doi.org/10.17882/39475
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Locations and mechanisms of ocean ventilation in the high-latitude North Atlantic in an eddy-permitting ocean model ArchiMer
Macgilchrist, Graeme A.; Johnson, Helen L.; Marshall, David P.; Lique, Camille; Thomas, Matthew; Jackson, Laura C.; Wood, Richard A..
A substantial fraction of the deep ocean is ventilated in the high-latitude North Atlantic. Consequently, the region plays a crucial role in transient climate change through the uptake of carbon dioxide and heat. However, owing to the Lagrangian nature of the process, many aspects of deep Atlantic Ocean ventilation and its representation in climate simulations remain obscure. We investigate the nature of ventilation in the high latitude North Atlantic in an eddy-permitting numerical ocean circulation model using a comprehensive set of Lagrangian trajectory experiments. Backwards-in-time trajectories from a model-defined ‘North Atlantic DeepWater’ (NADW) reveal the locations of subduction from the surface mixed layer at high spatial resolution. The major...
Tipo: Text Palavras-chave: North Atlantic Ocean; Atmosphere-ocean interaction; Lagrangian circulation/transport; Ocean circulation; Boundary currents; Diapycnal mixing.
Ano: 2020 URL: https://archimer.ifremer.fr/doc/00646/75833/76825.pdf
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Wave-Current Interactions at Meso and Submesoscales: Insights from Idealized Numerical Simulations ArchiMer
Villas Bôas, Ana B.; Cornuelle, Bruce. D.; Mazloff, Matthew. R.; Gille, Sarah. T.; Ardhuin, Fabrice.
Surface gravity waves play a major role in the exchange of momentum, heat, energy, and gases between the ocean and the atmosphere. The interaction between currents and waves can lead to variations in the wave direction, frequency, and amplitude. In the present work, we use an ensemble of synthetic currents to force the wave model WAVEWATCH III and assess the relative impact of current divergence and vorticity in modifying several properties of the waves, including direction, period, directional spreading, and significant wave height (Hs). We find that the spatial variability of Hs is highly sensitive to the nature of the underlying current and that refraction is the main mechanism leading to gradients of Hs. The results obtained using synthetic currents...
Tipo: Text Palavras-chave: Ocean; Sea/ocean surface; Atmosphere-ocean interaction; Mesoscale processes; Waves; Oceanic; Numerical analysis/modeling.
Ano: 2020 URL: https://archimer.ifremer.fr/doc/00654/76592/77740.pdf
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Insights into decadal North Atlantic sea surface temperature and ocean heat content variability from an eddy-permitting coupled climate model ArchiMer
Moat, B. I.; Sinha, B.; Josey, S. A.; Robson, J.; Ortega, P.; Sévellec, Florian; Holliday, N. P.; Mccarthy, G. D.; New, A. L.; Hirschi, J. J.-m..
An ocean mixed layer heat budget methodology is used to investigate the physical processes determining subpolar North Atlantic (SPNA) sea surface temperature (SST) and ocean heat content (OHC) variability on decadal-multidecadal timescales using the state-of-the-art climate model HadGEM3-GC2. New elements include development of an equation for evolution of anomalous SST for interannual and longer timescales in a form analogous to that for OHC, parameterization of the diffusive heat flux at the base of the mixed layer and analysis of a composite AMOC event. Contributions to OHC and SST variability from two sources are evaluated i) net ocean-atmosphere heat flux and ii) all other processes, including advection, diffusion and entrainment for SST. Anomalies in...
Tipo: Text Palavras-chave: Atmosphere-ocean interaction; Climate variability; Energy budget; Balance; Fluxes; Heat budgets; Fluxes; Surface temperature.
Ano: 2019 URL: https://archimer.ifremer.fr/doc/00502/61395/65060.pdf
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Effects of the submesoscale on the potential vorticity budget of ocean mode waters ArchiMer
Wenegrat, Jacob O.; Thomas, Leif N.; Gula, Jonathan; Mcwilliams, James C..
Non-conservative processes change the potential vorticity (PV) of the upper ocean, and later, through the subduction of surface waters into the interior, affect the general ocean circulation. Here we focus on how boundary layer turbulence, in the presence of submesoscale horizontal buoyancy gradients, generates a source of potential vorticity at the ocean surface through a balance known as the Turbulent ThermalWind. This source of PV injection at the submesoscale can be of similar magnitude to PV fluxes from the wind and surface buoyancy fluxes, and hence can lead to a net injection of PV onto outcropped isopycnals even during periods of surface buoyancy loss. The significance of these dynamics is illustrated using a high-resolution realistic model of the...
Tipo: Text Palavras-chave: Ageostrophic circulations; Atmosphere-ocean interaction; Fronts; Ocean dynamics; Potential vorticity; Boundary layer.
Ano: 2018 URL: http://archimer.ifremer.fr/doc/00452/56347/57937.pdf
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Subantarctic Mode Water Formation, Destruction, and Export in the Eddy-Permitting Southern Ocean State Estimate ArchiMer
Cerovecki, Ivana; Talley, Lynne D.; Mazloff, Matthew R.; Maze, Guillaume.
Subantarctic Mode Water (SAMW) is examined using the data-assimilating, eddy-permitting Southern Ocean State Estimate, for 2005 and 2006. Surface formation due to air–sea buoyancy flux is estimated using Walin analysis, and diapycnal mixing is diagnosed as the difference between surface formation and transport across 30°S, accounting for volume change with time. Water in the density range 26.5 < σθ < 27.1 kg m−3 that includes SAMW is exported northward in all three ocean sectors, with a net transport of (18.2, 17.1) Sv (1 Sv ≡ 106 m3 s−1; for years 2005, 2006); air–sea buoyancy fluxes form (13.2, 6.8) Sv, diapycnal mixing removes (−14.5, −12.6) Sv, and there is a volume loss of (−19.3, −22.9) Sv mostly occurring in the strongest SAMW formation...
Tipo: Text Palavras-chave: Atmosphere-ocean interaction; Buoyancy; Fluxes; Ocean circulation.
Ano: 2013 URL: http://archimer.ifremer.fr/doc/00154/26487/24596.pdf
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Surface Roughness Imaging of Currents Shows Divergence and Strain in the Wind Direction ArchiMer
Rascle, Nicolas; Chapron, Bertrand; Ponte, Aurelien; Ardhuin, Fabrice; Klein, Patrice.
Images of sea surface roughness-for example, obtained by synthetic aperture radars (SAR) or by radiometers viewing areas in and around the sun glitter-at times provide clear observations of meso- and sub-mesoscale oceanic features. Interacting with the surface wind waves, particular deformation properties of surface currents are responsible for those manifestations. Ignoring other sources of surface roughness variations, the authors limit their discussion to the mean square slope (mss) variability. This study confirms that vortical currents and currents with shear in the wind direction shall not be expressed in surface roughness images. Only divergent currents or currents with no divergence but strained in the wind direction can exhibit surface roughness...
Tipo: Text Palavras-chave: Circulation/ Dynamics; Ageostrophic circulations; Atmosphere-ocean interaction; Mesoscale processes; Wind waves; Atm/Ocean Structure/ Phenomena; Boundary layer; Sea state.
Ano: 2014 URL: https://archimer.ifremer.fr/doc/00210/32170/30619.pdf
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CMIP5 Model Intercomparison of Freshwater Budget and Circulation in the North Atlantic ArchiMer
Deshayes, Julie; Curry, Ruth; Msadek, Rym.
The subpolar North Atlantic is a center of variability of ocean properties, wind stress curl, and air-sea exchanges. Observations and hindcast simulations suggest that from the early 1970s to the mid-1990s the subpolar gyre became fresher while the gyre and meridional circulations intensified. This is opposite to the relationship of freshening causing a weakened circulation, most often reproduced by climate models. The authors hypothesize that both these configurations exist but dominate on different time scales: a fresher subpolar gyre when the circulation is more intense, at interannual frequencies (configuration A), and a saltier subpolar gyre when the circulation is more intense, at longer periods (configuration B). Rather than going into the detail of...
Tipo: Text Palavras-chave: Atmosphere-ocean interaction; Freshwater; Climate models; Model comparison; Climate variability; North Atlantic Oscillation.
Ano: 2014 URL: http://archimer.ifremer.fr/doc/00199/31024/29429.pdf
Registros recuperados: 11
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