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| Grodsky, Semyon A.; Kudryavtsev, Vladimir N.; Bentamy, Abderrahim; Carton, James A.; Chapron, Bertrand. |
| Scatterometer radar backscatter depends on the relationship linking surface stress and surface roughness. SST can alter the growth rate of centimeter-scale waves through its impact on air and water density and water viscosity. This SST-dependency has not been included in the standard Geophysical Model Functions. This study uses a radar imaging model to evaluate this SST-dependence and compares the results to observations from QuikScat Ku-band and ASCAT C-band scatterometers. A SST correction could raise wind speeds by up to 0.2 ms(-1) in the storm track region of the Southern Ocean for C-band scatterometers. For the higher frequency Ku-band scatterometers, a SST-induced reduction up to 0.4 ms(-1) is predicted south of 60(-S), where SST is cold and winds... |
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| Ano: 2012 |
URL: https://archimer.ifremer.fr/doc/00088/19898/17552.pdf |
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| Grodsky, Semyon A.; Reul, Nicolas; Lagerloef, Gary; Reverdin, Gilles; Carton, James A.; Chapron, Bertrand; Quilfen, Yves; Kudryavtsev, Vladimir N.; Kao, Hsun-ying. |
| At its seasonal peak the Amazon/Orinoco plume covers a region of 10^6 km2 in the western tropical Atlantic with more than 1m of extra freshwater, creating a near-surface barrier layer (BL) that inhibits mixing and warms the sea surface temperature (SST) to >29oC. Here new sea surface salinity (SSS) observations from the Aquarius/SACD and SMOS satellites help elucidate the ocean response to hurricane Katia, which crossed the plume in early fall, 2011. Its passage left a 1.5psu high haline wake covering >10^5 km2 (in its impact on density, the equivalent of a 3.5oC cooling) due to mixing of the shallow BL. Destruction of this BL apparently decreased SST cooling in the plume, and thus preserved higher SST and evaporation than outside. Combined with SST,... |
| Tipo: Text |
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| Ano: 2012 |
URL: https://archimer.ifremer.fr/doc/00094/20540/18943.pdf |
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| Golubkin, Pavel A.; Chapron, Bertrand; Kudryavtsev, Vladimir N.. |
| Wind-generated waves in the Kara, Laptev, and East-Siberian Seas are investigated using altimeter data from Envisat RA-2 and SARAL-AltiKa. Only isolated ice-free zones had been selected for analysis. Wind seas can be treated as pure wind-generated waves without any contamination by ambient swell. Such zones were identified using ice concentration data from microwave radiometers. Altimeter data, both significant wave height (SWH) and wind speed, for these areas were further obtained for the period 2002-2012 using Envisat RA-2 measurements, and for 2013 using SARAL-AltiKa. Dependencies of dimensionless SWH and wavelength on dimensionless wave generation spatial scale are compared to known empirical dependencies for fetch-limited wind wave development. We... |
| Tipo: Text |
Palavras-chave: Altimetry; Remote sensing; Satellite altimeter; Significant wave height; Wind speed. |
| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00302/41330/40642.pdf |
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| Kudryavtsev, Vladimir N.; Chapron, Bertrand; Myasoedov, Alexander G.; Collard, Fabrice; Johannessen, Johnny A.. |
| An effective methodology using satellite high-resolution polarized information to interpret and quantitatively assess various surface ocean phenomena is suggested. Using a sample RADARSAT-2 quad-polarization ocean synthetic aperture radar (SAR) scene, the dual co-polarization (VV and HH) radar data are combined into polarization difference, polarization ratio, and nonpolarized components. As demonstrated, these field quantities provide means to distinguish Bragg scattering mechanism and radar returns from breaking waves. As shown, quantitative characteristics of the surface manifestation of ocean currents, slicks, and wind field features in these dual co-polarization properties are very different and may be effectively used in the development of new SAR... |
| Tipo: Text |
Palavras-chave: Radar cross sections; Radar signal analysis; Synthetic aperture radar (SAR) imaging. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00149/26042/24890.pdf |
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