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| D'Ovidio, Francesco; Isern-fontanet, Jordi; Lopez, Cristobal; Hernandez Garcia, Emilio; Garcia Ladona, Emilio. |
| Transport and mixing properties of surface currents can be detected from altimetric data by both Eulerian and Lagrangian diagnostics. In contrast with Eulerian diagnostics, Lagrangian tools like the local Lyapunov exponents have the advantage of exploiting both spatial and temporal variability of the velocity field and are in principle able to unveil subgrid filaments generated by chaotic stirring. However, one may wonder whether this theoretical advantage is of practical interest in real-data, mesoscale and sub-mesoscale analysis, because of the uncertainties and resolution of altimetric products, and the non-passive nature of biogeochemical tracers. Here we compare the ability of standard Eulerian diagnostics and the finite-size Lyapunov exponent in... |
| Tipo: Text |
Palavras-chave: Lagrangian dynamics; Mediterranean circulation; Altimetry; Filaments; Sub mesoscale. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/2009/publication-6136.pdf |
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| Turiel, A.; Isern-fontanet, Jordi; Garcia-ladona, E.; Young, J. A.. |
| We demonstrate the potential of monitoring coherent wave fronts on the tropical ocean surface using an advanced detection algorithm applied to visible sunglintaffected imagery from geostationary satellites. Data from MeteoSat are processed with the advanced analysis technique to reveal transient wave activity near and to the west of the Mascarene Ridge of the western Indian Ocean. The technique is based on a wavelet-based singularity analysis which enhances the subtle but highly coherent wave patterns in the meteorological satellite data. It is likely that the patterns represent internal ocean waves, a pathway to ocean mixing and climate. The prospect for using this detection algorithm in greatly expanded satellite global surveys of wave activity is... |
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| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/publication-3078.pdf |
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| Klein, Patrice; Isern-fontanet, Jordi; Lapeyre, Guillaume; Roullet, G.; Danioux, Eric; Chapron, Bertrand; Le Gentil, Sylvie; Sasaki, H.. |
| A surface Quasi-Geostrophy based (eSQG) method to diagnose the vertical velocity field from Sea Surface Height (SSH) is assessed using high resolution simulations. These simulations concern a turbulent eddy field with large Rossby numbers and energetic wind-driven motions. Results indicate that low-frequency vertical velocities (and also horizontal motions) can be reconstructed within a range of scales between 20 km and 400 km from the surface down to 500 m. The only information needed is a single high-resolution SSH snapshot and information on the large-scale vertical stratification. Inertial motions are naturally filtered because they do not contaminate SSH as we demonstrate. These results are encouraging and further strengthen previous studies using the... |
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| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/00000/11094/7418.pdf |
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| Isern-fontanet, Jordi; Turiel, A; Garcia Ladona, E; Font, J. |
| In this paper we investigate the validity of the multifractal formalism to study sea surface temperature ( SST). It is shown that SST patterns observed in moderate resolution SST images have anomalous scaling properties characteristic of a multifractal structure. The most probable origin of the observed structures is the turbulent character of the oceanic flow as they evolve slowly and are very persistent in times compatible with ocean mesoscale dynamics ( several days). The spectrum of singularity exponents indicates that the dynamics of the processes leading to the geometrical arrangement of the SST patterns is quite general over the available range of scales. As a consequence, multifractal techniques can be used to extract properties of the underlying... |
| Tipo: Text |
Palavras-chave: Operational oceanography; Remote sensing; MSS method. |
| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/publication-2644.pdf |
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| Isern-fontanet, Jordi; Chapron, Bertrand; Lapeyre, Guillaume; Klein, Patrice. |
| In this paper, we examine the emerging potential offered by satellite microwave radiometer SST measurements to complement altimeter data to quantitatively derive surface ocean currents. The proposed methodology does not follow standard sequential temporal analysis but follows the application of the Surface Quasi-Geostrophic (SQG) theory. Accordingly, under favourable environmental conditions, the implementation for this methodology is simple and robust, and most importantly, solely requires a single SST image. For the present demonstration, altimetric measurements are used to infer a necessary adjustment to match the kinetic energy level for length scales smaller than 300 km. This helps to derive a regional effective Brunt-Vaisala frequency to produce SQG... |
| Tipo: Text |
Palavras-chave: Microwave radiometers; Sea surface temperature; Surface quasi geostrophy. |
| Ano: 2006 |
URL: http://archimer.ifremer.fr/doc/2006/publication-2177.pdf |
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| Gommenginger, Christine; Chapron, Bertrand; Hogg, Andy; Buckingham, Christian; Fox-kemper, Baylor; Eriksson, Leif; Soulat, Francois; Ubelmann, Clément; Ocampo-torres, Francisco; Nardelli, Bruno Buongiorno; Griffin, David; Lopez-dekker, Paco; Knudsen, Per; Andersen, Ole; Stenseng, Lars; Stapleton, Neil; Perrie, William; Violante-carvalho, Nelson; Schulz-stellenfleth, Johannes; Woolf, David; Isern-fontanet, Jordi; Ardhuin, Fabrice; Klein, Patrice; Mouche, Alexis; Pascual, Ananda; Capet, Xavier; Hauser, Daniele; Stoffelen, Ad; Morrow, Rosemary; Aouf, Lotfi; Breivik, Øyvind; Fu, Lee-lueng; Johannessen, Johnny A.; Aksenov, Yevgeny; Bricheno, Lucy; Hirschi, Joel; Martin, Adrien Ch; Martin, Adiran P; Nurser, George; Polton, Jeff; Wolf, Judith; Johnsen, Harald; Soloviev, Alexander; Jacobs, Gregg A.; Collard, Fabrice; Groom, Steve; Kudryavtsev, Vladimir; Wilkin, John; Navarro, Victor; Babanin, Alex; Martin, Matthew; Siddorn, John; Saulter, Andrew; Rippeth, Tom; Emery, Bill; Maximenko, Nikolai; Romeiser, Roland; Graber, Hans; Azcarate, Aida Alvera; Hughes, Chris W.; Vandemark, Doug; Silva, Jose Da; Leeuwen, Peter Jan Van; Naveira-garabato, Alberto; Gemmrich, Johannes; Mahadevan, Amala; Marquez, Jose; Munro, Yvonne; Doody, Sam; Burbidge, Geoff. |
| High-resolution satellite images of ocean color and sea surface temperature reveal an abundance of ocean fronts, vortices and filaments at scales below 10 km but measurements of ocean surface dynamics at these scales are rare. There is increasing recognition of the role played by small scale ocean processes in ocean-atmosphere coupling, upper-ocean mixing and ocean vertical transports, with advanced numerical models and in situ observations highlighting fundamental changes in dynamics when scales reach 1 km. Numerous scientific publications highlight the global impact of small oceanic scales on marine ecosystems, operational forecasts and long-term climate projections through strong ageostrophic circulations, large vertical ocean velocities and mixed layer... |
| Tipo: Text |
Palavras-chave: Satellite; Air sea interactions; Upper ocean dynamics; Submesoscale; Coastal; Marginal ice zone; Radar; Along-track interferometry. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00510/62121/66325.pdf |
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| Isern-fontanet, Jordi; Lapeyre, Guillaume; Klein, Patrice; Chapron, Bertrand; Hecht, M. |
| The ability to reconstruct the three-dimensional (3D) dynamics of the ocean by an effective version of Surface Quasi-Geostrophy (eSQG) is examined. Using the fact that surface density plays an analogous role as interior potential vorticity (PV), the eSQG method consists in inverting the QG PV generated by sea-surface density only. We also make the extra assumption that sea-surface temperature (SST) anomalies fully represent surface density anomalies. This approach requires a single snapshot of SST and the setup of two parameters: the mean Brunt-Vaisala frequency and a parameter that determines the energy level at the ocean surface. The validity of this approach is tested using an Ocean General Circulation Model simulation representing the North Atlantic in... |
| Tipo: Text |
Palavras-chave: 3D dynamics reconstruction; SST; Surface Quasi Geostrophy. |
| Ano: 2008 |
URL: http://archimer.ifremer.fr/doc/2008/publication-4620.pdf |
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