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| Registros recuperados: 211 | |
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| Zabolotskikh, Elizaveta V.; Gurvich, Irina A.; Chapron, Bertrand. |
| With the sea-ice decline over the eastern part of the Eurasian Arctic (EEA), polar mesocyclones (MCs) and their most intensive representatives-polar lows (PLs)-can occur over more open-water areas. Visible and infrared MODIS images, active and passive microwave spaceborne instruments, and ERA Interim reanalysis data are combined and used to analyze the synoptic situations and to infer the factors influencingMC appearance and evolution over the Kara Sea, the Laptev Sea, the East Siberian Sea, and the Chukchi Sea. In recent years, the Arctic more often loses its summer sea-ice cover, and PLs may more commonly emerge within open-water Eastern Arctic regions during fall and summer months. This conclusion is derived basing on the analysis of more than 150 MCs... |
| Tipo: Text |
Palavras-chave: Arctic; Geoscience; Mesoscale cyclones. |
| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00358/46870/48388.pdf |
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| Hanafin, Jennifer; Quilfen, Yves; Ardhuin, Fabrice; Sienkiewicz, Joseph; Queffeulou, Pierre; Obrebski, Mathias; Chapron, Bertrand; Reul, Nicolas; Collard, Fabrice; Corman, David; De Azevedo, Eduardo B.; Vandemark, Doug; Stutzmann, Eleonore. |
| Tipo: Text |
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| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00094/20538/18197.pdf |
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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... |
| Tipo: Text |
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| Ano: 2012 |
URL: https://archimer.ifremer.fr/doc/00088/19898/17552.pdf |
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| Kudryavtsev, Vladimir; Myasoedov, Alexander; Chapron, Bertrand; Johannessen, Johnny A.; Collard, Fabrice. |
| A synergetic approach for quantitative analysis of high-resolution ocean synthetic aperture radar (SAR) and imaging spectrometer data, including the infrared (IR) channels, is suggested. This approach first clearly demonstrates that sea surface roughness anomalies derived from Sun glitter imagery compare very well to SAR roughness anomalies. As further revealed using these fine-resolution (similar to 1 km) observations, the derived roughness anomaly fields are spatially correlated with sharp gradients of the sea surface temperature (SST) field. To quantitatively interpret SAR and optical (in visible and IR ranges) images, equations are derived to relate the "surface roughness" signatures to the upper ocean flow characteristics. As developed, a direct link... |
| Tipo: Text |
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| Ano: 2012 |
URL: https://archimer.ifremer.fr/doc/00079/18999/16570.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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| Kudryavtsev, V; Akimov, D; Johannessen, Johnny; Chapron, Bertrand. |
| [1] A new radar imaging model of ocean current features is proposed. The simulated normalized radar cross section ( NRCS) takes into account scattering from "regular'' surfaces ( by means of resonant Bragg scattering and specular reflections) and scattering from breaking waves. The description of background wind waves and their transformation in nonuniform medium is based on solution of the wave action conservation equation. Wave breaking plays a key role in the radar imaging model. Breaking waves scatter radio waves ( thus directly contributing to the NRCS), provide energy dissipation in wind waves ( thus defining the wave spectrum of intermediate scale waves), and generate short surface waves ( thus affecting Bragg scattering). Surface current,... |
| Tipo: Text |
Palavras-chave: Breaking waves; Scattering; Radar imaging model; Ocean surface current. |
| Ano: 2005 |
URL: http://archimer.ifremer.fr/doc/2005/publication-762.pdf |
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| Nouguier, Frederic; Chapron, Bertrand; Guerin, Charles-antoine. |
| We revisit and supplement the description of gravity waves based on perturbation expansions in Lagrangian coordinates. A general analytical framework is developed to derive a second-order Lagrangian solution to the motion of arbitrary surface gravity wave fields in a compact and vectorial form. The result is shown to be consistent with the classical second-order Eulerian expansion by Longuet-Higgins (J. Fluid Mech., vol. 17, 1963, pp. 459-480) and is used to improve the original derivation by Pierson (1961 Models of random seas based on the Lagrangian equations of motion. Tech. Rep. New York University) for long-crested waves. As demonstrated, the Lagrangian perturbation expansion captures nonlinearities to a higher degree than does the corresponding... |
| Tipo: Text |
Palavras-chave: Surface gravity waves; Waves/free-surface flows. |
| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00274/38476/37042.pdf |
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| Tran, Ngan; Chapron, Bertrand; Vandemark, D. |
| This letter uses a large ocean satellite data set to document relationships between Ku-band radar backscatter (sigma-0) of the sea surface, near-surface wind speed (U), and ocean wave height (SWH). The observations come from satellite crossovers of the Tropical Rainfall Mapping Mission (TRMM) Precipitation Radar (PR) and two satellite altimeters, namely: 1) Jason-1 and 2) ENVISAT. At these nodes, we obtain TRMM clear-air normalized radar cross-section data along with coincident altimeter-derived significant wave height. Wind speed estimates come from the European Centre for Medium-Range Weather Forecast. TRMM PR is the first satellite to measure low incidence Ku-band ocean backscatter at a continuum of incidence angles from 0 degrees to 18 degrees. This... |
| Tipo: Text |
Palavras-chave: Space borne radar; Scattering; Radar cross section; Altimetry. |
| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/publication-3299.pdf |
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| Husson, R.; Ardhuin, Fabrice; Collard, Fabrice; Chapron, Bertrand; Balanche, Abel. |
| Swells radiating across ocean basins are fingerprints of the large ocean storms that generated them, which are otherwise poorly observed. Here we analyze the signature of one swell event in the seismic noise recorded all around the Pacific and we show that it is a natural complement to the global coverage provided by the Synthetic Aperture Radar wave mode data from ENVISAT. In particular the seismic stations are much more sensitive to low frequency and amplitude signals than buoys and SAR, capturing swell forerunners a couple of days before they can be detected from space or in situ data. This information helps detect in the SAR measurements the presence of very long swell, with periods of 22 s in our case example, that were otherwise excluded. Citation:... |
| Tipo: Text |
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| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00092/20328/17977.pdf |
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| Quilfen, Yves; Prigent, C; Chapron, Bertrand; Mouche, Alexis; Houti, N. |
| The physics of remote sensing sea surface measurements is still poorly understood under severe weather conditions. Wind vector algorithms are usually developed for non-precipitating atmospheres and for wind speeds less than 20 m/s. In this study, we analyze observations from the QuikSCAT Ku-band scatterometer collocated with the WindSat full polarimetric microwave radiometer to estimate the potential of these two instruments for sea surface wind retrieval under severe weather conditions. The Jason altimeter provides independent measurements of wind speed and rain rate for comparison purposes. The sensitivity of the radar cross-sections and brightness temperatures to the wind speed and direction is directly studied from the observations and compared with... |
| Tipo: Text |
Palavras-chave: Winds; Scatterometer; Radiometer. |
| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/publication-6393.pdf |
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| Bentamy, Abderrahim; Grodsky, Semyon A.; Chapron, Bertrand; Carton, James A.. |
| Global winds provided by satellite scatterometry are an important aspect of the ocean observing system. Many applications require well-calibrated time series of winds over time periods spanned by multiple missions. But sensors on individual satellites differ, introducing differences in wind estimates. This study focuses on global winds from two scatterometers, ERS-2 (1996-2001) and QuikSCAT (1999-2009) that show persistent differences during their period of overlap (July-1999 to January 2001). We examine a set of collocated observations during this period to evaluate the causes of these differences. The use of different operating frequencies leads to differences that depend on rain rate, wind velocity, and SST. The enhanced sensitivity to rain rate of the... |
| Tipo: Text |
Palavras-chave: Scatterometer winds; SST; Inter-instrument bias. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00139/25071/23190.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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| Reul, Nicolas; Tenerelli, Joseph; Chapron, Bertrand; Vandemark, Doug; Quilfen, Yves; Kerr, Yann. |
| The Soil Moisture and Ocean Salinity (SMOS) mission currently provides multiangular L-band (1.4 GHz) brightness temperature images of the Earth. Because upwelling radiation at 1.4 GHz is significantly less affected by rain and atmospheric effects than at higher microwave frequencies, these new SMOS measurements offer unique opportunities to complement existing ocean satellite high wind observations that are often contaminated by heavy rain and clouds. To illustrate this new capability, we present SMOS data over hurricane Igor, a tropical storm that developed to a Saffir-Simpson category 4 hurricane from 11 to 19 September 2010. Thanks to its large spatial swath and frequent revisit time, SMOS observations intercepted the hurricane 9 times during this... |
| Tipo: Text |
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| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00067/17805/15330.pdf |
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| 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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| 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... |
| Tipo: Text |
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| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/00000/11094/7418.pdf |
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| Johannessen, Ja; Chapron, Bertrand; Collard, F; Rio, Mh; Piolle, Jean-francois; Gaultier, Lucile; Quartly, G; Shutler, J; Escola, R; Raj, Rp; Donlon, C; Danielson, R; Korosov, Anton; Nencioli, F; Roca, M; Hansen, M. |
| Tipo: Text |
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| Ano: 2018 |
URL: http://archimer.ifremer.fr/doc/00450/56152/57695.pdf |
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| Registros recuperados: 211 | |
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