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| Johannessen, J; Chapron, Bertrand; Collard, F; Kudryavtsev, V; Mouche, Alexis; Akimov, D; Dagestad, K. |
| Previous analysis of Advanced Synthetic Aperture Radar (ASAR) signals collected by ESA's Envisat has demonstrated a very valuable source of high-resolution information, namely, the line-of-sight velocity of the moving ocean surface. This velocity is estimated from a Doppler frequency shift, consistently extracted within the ASAR scenes. The Doppler shift results from the combined action of near surface wind on shorter waves, longer wave motion, wave breaking and surface current. Both kinematic and dynamic properties of the moving ocean surface roughness can therefore be derived from the ASAR observations. The observations are compared to simulations using a radar imaging model extended to include a Doppler shift module. The results are promising.... |
| Tipo: Text |
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| Ano: 2008 |
URL: http://archimer.ifremer.fr/doc/2008/publication-5168.pdf |
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| Johannessen, J; Balmino, G; Le Provost, C; Rummel, R; Sabadini, R; Sunkel, H; Tscherning, C; Visser, P; Woodworth, P; Hughes, C; Le Grand, Pascal; Sneeuw, N; Perosanz, F; Aguirre Fernandez, M; Rebhan, H; Drinkwater, M. |
| Current knowledge of the Earth's gravity field and its geoid, as derived from various observing techniques and sources, is incomplete. Within a reasonable time, substantial improvement will come by exploiting new approaches based on spaceborne gravity observation. Among these, the European Space Agency (ESA) Gravity field and steady-state Ocean Circulation Explorer (GOCE) satellite mission concept has been conceived and designed taking into account multi-disciplinary research objectives in solid Earth physics, oceanography and geodesy. Based on the unique capability of a gravity gradiometer combined with satellite-to-satellite high-low tracking techniques, an accurate and detailed global model of the Earth's gravity field and its corresponding geoid will... |
| Tipo: Text |
Palavras-chave: M1; M1; M1. |
| Ano: 2003 |
URL: https://archimer.ifremer.fr/doc/2003/publication-493.pdf |
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| Johannessen, J; Kudryavtsev, V; Akimov, D; Eldevik, T; Winther, N; Chapron, Bertrand. |
| [1] The surface signatures of meandering fronts and eddies have been regularly observed and documented in synthetic aperture radar (SAR) images. Wave-current interactions, the suppression of short wind waves by natural film, and the varying wind field resulting from atmospheric boundary layer changes across an oceanic temperature front all contribute to the radar image manifestation of such mesoscale features. The corresponding imaging mechanisms are quantitatively explored using a new radar imaging model (Kudryavtsev et al., 2005) that solves the energy balance equation where wind forcing, viscous and wave breaking dissipation, wave-wave interactions, and generation of short waves by breaking waves are taken into account. High-quality and synoptic in situ... |
| Tipo: Text |
Palavras-chave: Mesoscale feature detection; Imaging radar model. |
| Ano: 2005 |
URL: http://archimer.ifremer.fr/doc/2005/publication-1352.pdf |
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