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| Registros recuperados: 18 | |
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| Morrow, Rosemary; Fu, Lee-lueng; Ardhuin, Fabrice; Benkiran, Mounir; Chapron, Bertrand; Cosme, Emmanuel; D’ovidio, Francesco; Farrar, J. Thomas; Gille, Sarah T.; Lapeyre, Guillaume; Le Traon, Pierre-yves; Pascual, Ananda; Ponte, Aurelien; Qiu, Bo; Rascle, Nicolas; Ubelmann, Clement; Wang, Jinbo; Zaron, Edward D.. |
| The future international Surface Water and Ocean Topography (SWOT) Mission, planned for launch in 2021, will make high-resolution 2D observations of sea-surface height using SAR radar interferometric techniques. SWOT will map the global and coastal oceans up to 77.6∘ latitude every 21 days over a swath of 120 km (20 km nadir gap). Today’s 2D mapped altimeter data can resolve ocean scales of 150 km wavelength whereas the SWOT measurement will extend our 2D observations down to 15–30 km, depending on sea state. SWOT will offer new opportunities to observe the oceanic dynamic processes at scales that are important in the generation and dissipation of kinetic energy in the ocean, and that facilitate the exchange of energy between the ocean interior and the... |
| Tipo: Text |
Palavras-chave: Ocean mesoscale circulation; Satellite altimetry; SAR-interferometry; Tides and internal tides; Calibration-validation. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00495/60685/64181.pdf |
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| Ponte, Aurelien; Klein, Patrice. |
| The non persistent phase relationship between internal tides and astronomical forcings, also known as incoherence, has been identified as a major question in the context of future wide-swath satellite altimetry. This study addresses this issue using a novel set of numerical experiments where a plane-wave/low-mode internal tide propagates through a turbulent mesoscale eddy field. These experiments demonstrate the emergence of internal tide incoherence as the eddy turbulence is strengthened. In strongly turbulent situations, the internal tide signature on sea level forms complex interference patterns with large amplifications of the initial internal wave. These patterns evolve more rapidly than the signature of the turbulent eddy field on sea level. The... |
| Tipo: Text |
Palavras-chave: Internal tide; Wide-swath altimetry; Mesoscale turbulence; Incoherence. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00254/36571/35109.pdf |
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| González-haro, Cristina; Ponte, Aurelien; Autret, Emmanuelle. |
| The expected amplitude of fixed-point sea surface temperature (SST) fluctuations induced by barotropic and baroclinic tidal flows is estimated from tidal current atlases and SST observations. The fluctuations considered are the result of the advection of pre-existing SST fronts by tidal currents. They are thus confined to front locations and exhibit fine-scale spatial structures. The amplitude of these tidally induced SST fluctuations is proportional to the scalar product of SST frontal gradients and tidal currents. Regional and global estimations of these expected amplitudes are presented. We predict barotropic tidal motions produce SST fluctuations that may reach amplitudes of 0.3 K. Baroclinic (internal) tides produce SST fluctuations that may reach... |
| Tipo: Text |
Palavras-chave: Sea surface temperature; Satellite observations; Tidal currents; Internal tides. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00589/70075/68048.pdf |
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| Yu, Xiaolong; Ponte, Aurelien; Elipot, Shane; Menemenlis, Dimitris; Zaron, Edward D.; Abernathey, Ryan. |
| The surface kinetic energy of a 1/48° global ocean simulation and its distribution as a function of frequency and location are compared with the one estimated from 15,329 globally distributed surface drifter observations at hourly resolution. These distributions follow similar patterns with a dominant low‐frequency component and well‐defined tidal and near‐inertial peaks globally. Quantitative differences are identified with deficits of low‐frequency energy near the equator (factor 2) and at near‐inertial frequencies (factor 3) and an excess of energy at semidiurnal frequencies (factor 4) for the model. Owing to its hourly resolution and its near‐global spatial coverage, the array of surface drifters is an invaluable tool to evaluate the realism of... |
| Tipo: Text |
Palavras-chave: LLC4320; Surface drifter; Rotary spectrum; SWOT. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00514/62517/66817.pdf |
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| Morel, Yves; Gula, Jonathan; Ponte, Aurelien. |
| Taking advantage of alternative expressions for potential vorticity (PV) in divergence forms, we derive balances between volume integral of PV and boundary conditions, that are then applied to practical computations of PV: • we propose a new method for diagnosing the Ertel potential vorticity from model output, that preserves the balances; • we show how the expression of PV can be derived in general coordinate systems. This is here emphasised with isopycnic coordinates by generalising the PV expression to the general Navier-Stokes equations; • we propose a generalised derivation for the Haynes-McIntyre impermeability theorem, which highlights the role of the bottom boundary condition choice (e.g. no-slip vs free-slip) and mixing near the bottom boundary... |
| Tipo: Text |
Palavras-chave: Potential vorticity; Boundary conditions; General circulation; Vortex; Fronts; Boundary layers. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00494/60525/63988.pdf |
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| Rascle, Nicolas; Nouguier, Frederic; Chapron, Bertrand; Mouche, Alexis; Ponte, Aurelien. |
| At times, high resolution images of sea surface roughness can provide stunning details of submesoscale upper ocean dynamics. As interpreted, transformations of short scale wind waves by horizontal current gradients are responsible for those spectacular observations. Those observations could prove particularly useful to validate numerical ocean models which reach increasingly high resolutions. Focusing on surface roughness at optical wavelengths, two steps have recently been performed in that direction. First, it was shown by Rascle et al. (2014, Journal of Physical Oceanography) that surface roughness variations not only trace surface current divergence but also other characteristics of the current gradient tensor, mainly the strain in the wind direction.... |
| Tipo: Text |
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| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00358/46878/46759.pdf |
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| Eynard-bontemps, Guillaume; Abernathey, Ryan; Hamman, Joseph; Ponte, Aurelien; Rath, Willi. |
| Pangeo[1] is a community-driven effort for open-source big data initially focused on the Earth System Sciences. One of its primary goals is to enable scientists in analyzing petascale datasets both on classical high-performance computing (HPC) and on public cloud infrastructure. In only a few years, Pangeo has grown into a very productive community collaborating on the development of open-source analysis tools for science. It provides a set of example deployments based on open-source Scientific Python packages like Jupyter[2], Dask[3], and Xarray[4] that bring together scientists and developer with their actual use-cases. In this paper, we first describe Pangeo ecosystem and community. We then present its impact on the work of scientists from CNES on the... |
| Tipo: Text |
Palavras-chave: Pangeo; Dask; Jupyter; HPC; Cloud; Big Data; Analysis; Open Source. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00503/61441/65160.pdf |
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| Yu, Xiaolong; Ponte, Aurelien; Lahaye, Noe; Caspar-cohen, Zoe; Menemenlis, Dimitris. |
| urrent satellite altimeters map sea surface height (SSH) with an effective spatial scale of O(100 km) and, as a result, surface ocean velocity can be appropriately estimated from merged SSH fields by assuming geostrophic equilibrium. The validity of the geostrophic assumption down to the spatial scale of O(10 km) that will be newly resolved by the next generation of satellite altimeters, such as the Surface Water Ocean Topography (SWOT) mission, remains unknown. In this study, the accuracy of geostrophy for the estimation of surface currents from a knowledge of instantaneous sea level is quantified using the hourly fields from a tide- and eddy-resolving global numerical simulation. Geostrophic balance is found to be the leading-order balance in frontal... |
| Tipo: Text |
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| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00688/79962/82890.pdf |
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| Ponte, Aurelien; Klein, Patrice; Capet, Xavier; Le Traon, Pierre-yves; Chapron, Bertrand; Lherminier, Pascale. |
| High-resolution numerical experiments of ocean mesoscale eddy turbulence show that the wind-driven mixed layer (ML) dynamics affects mesoscale motions in the surface layers at scales lower than O(60 km). At these scales, surface horizontal currents are still coherent to, but weaker than, those derived from sea surface height using geostrophy. Vertical motions, on the other hand, are stronger than those diagnosed using the adiabatic quasigeotrophic (QG) framework. An analytical model, based on a scaling analysis and on simple dynamical arguments, provides a physical understanding and leads to a parameterization of these features in terms of vertical mixing. These results are valid when the wind-driven velocity scale is much smaller than that associated with... |
| Tipo: Text |
Palavras-chave: Mesoscale processes; Ocean dynamics; Turbulence. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00170/28076/26291.pdf |
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| Odaka, Tina; Banihirwe, Anderson; Eynard-bontemps, Guillaume; Ponte, Aurelien; Maze, Guillaume; Paul, Kevin; Baker, Jared; Abernathey, Ryan. |
| The Pangeo ecosystem is an interactive computing software stack for HPC and public cloud infrastructures. In this paper, we show benchmarking results of the Pangeo platform on two di erent HPC sys- tems. Four di erent geoscience operations were considered in this bench- marking study with varying chunk sizes and chunking schemes. Both strong and weak scaling analyses were performed. Chunk sizes between 64MB to 512MB were considered, with the best scalability obtained for 512MB. Compared to certain manual chunking schemes, the auto chunk- ing scheme scaled well. |
| Tipo: Text |
Palavras-chave: Pangeo; Interactive computing; HPC; Cloud; Benchmarking; Dask; Xarray. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00597/70946/69187.pdf |
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| Ponte, Aurelien; Klein, Patrice; Dunphy, Michael; Le Gentil, Sylvie. |
| The performance of a tentative method that disentangles the contributions of a low-mode internal tide on sea level from that of the balanced mesoscale eddies is examined using an idealized high resolution numerical simulation. This disentanglement is essential for proper estimation from sea level of the ocean circulation related to balanced motions. The method relies on an independent observation of the sea surface water density whose variations are 1/dominated by the balanced dynamics and 2/correlate with variations of potential vorticity at depth for the chosen regime of surface-intensified turbulence. The surface density therefore leads via potential vorticity inversion to an estimate of the balanced contribution to sea level fluctuations. The... |
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| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00374/48487/48761.pdf |
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| Dunphy, Michael; Ponte, Aurelien; Klein, Patrice; Le Gentil, Sylvie. |
| Understanding how internal tides distort and lose coherence as they propagate through the ocean has been identified as a key issue for interpreting data from the upcoming wide-swath altimeter mission SWOT. This study addresses that issue through the analysis of numerical experiments where a low mode internal tide propagates through a quasi-geostrophic turbulent jet. We present a set of reduced equations based on vertical mode projections that describe the dynamics of the low-mode internal tides as they propagate through the slower turbulent field. Diagnostics of the terms responsible for the interaction between the wave and the slow circulation are computed from the numerical outputs. The large scale change of stratification, on top of eddies and jet... |
| Tipo: Text |
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| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00342/45364/44853.pdf |
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| Ponte, Aurelien; Cornuelle, Bruce D.. |
| The propagation of remotely generated superinertial internal tides constitutes a difficulty for the modelling of regional ocean tidal variability which we illustrate in several ways. First, the M2 tidal solution inside a control region located along the Southern California Bight coastline is monitored while the extent of the numerical domain is increased (up to 512 x 512 km). While the amplitude and phase of sea level averaged over the region is quasi-insensitive to domain size, a steady increase of kinetic energy, predominantly baroclinic, is observed with increasing domain size. The increasing flux of energy into the control region suggests that this trend is explained by the growing contribution from remote generation sites of internal tide which can... |
| Tipo: Text |
Palavras-chave: Barotropic tide; Baroclinic tide; Internal tide; Coastal dynamics; Domain size sensitivity; Energy budgets. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00124/23566/21467.pdf |
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| Registros recuperados: 18 | |
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