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| Registros recuperados: 39 | |
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| Bentamy, Abderrahim; Katsaros, Kristina; Queffeulou, Pierre. |
| This chapter addresses the estimation of global surface winds, surface wind stress, latent heat flux, and sensible heat flux over the oceans with high spatial and temporal resolution using satellite radar and radiometer measurements. An overview of the physics of remotely sensed data, of methods and algorithms used to retrieve surface fluxes is provided. The retrievals are used to estimate regular in space and time surface parameters, requested for oceanic forcing function, over global ocean. The characteristics of the former are investigated at global and regional scales. |
| Tipo: Text |
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| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00030/14101/11333.pdf |
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| Bentamy, Abderrahim; Grodsky, Semyon A.; Katsaros, Kristina; Mestas-nunez, Alberto M.; Blanke, Bruno; Desbiolles, Fabien. |
| A new method is developed to estimate daily turbulent airsea fluxes over the global ocean on a 0.25 degrees grid. The required surface wind speed (w(10)) and specific air humidity (q(10)) at 10m height are both estimated from remotely sensed measurements. w(10) is obtained from the SeaWinds scatterometer on board the QuikSCAT satellite. A new empirical model relating brightness temperatures (T-b) from the Special Sensor Microwave Imager (SSM/I) and q(10) is developed. It is an extension of the author's previous q(10) model. In addition to T-b, the empirical model includes sea surface temperature (SST) and airsea temperature difference data. The calibration of the new empirical q(10) model utilizes q(10) from the latest version of the National Oceanography... |
| Tipo: Text |
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| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00137/24825/23575.pdf |
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| Grodsky, Semyon A.; Carton, James A.; Bentamy, Abderrahim. |
| In the presence of stable near-surface haline stratification, intermittent cold sea surface temperature (SST, upwelling) events produced by gap winds off the Central American Pacific coast should be accompanied by uplifts of saltier water. We illustrate that Aquarius satellite sea surface salinity (SSS) captures these high SSS events. In boreal winter when the intense gap winds are frequent, two tongues of anomalously salty water develop off the Gulfs of Tehuantepec and Papagayo. During that season the average SSS in the meridionally oriented Tehuantepec tongue is about 0.4 psu saltier than the background SSS. The zonally elongated Papagayo tongue stands out even more strongly, being 1-2 psu saltier than SSS in the neighbouring Panama Bight. The spatial... |
| Tipo: Text |
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| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00211/32184/30751.pdf |
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| Desbiolles, Fabien; Blanke, Bruno; Bentamy, Abderrahim; Grima, Nicolas. |
| Numerous studies have shown the primary importance of wind stress curl in coastal upwelling dynamics. The main goal of this new analysis is to describe the QuikSCAT surface wind stress curl at various scales in the Benguela and Canary upwelling systems. The dominant spatial pattern is characterized by cyclonic curl near continental boundaries and anticyclonic curl offshore, in association with equatorward alongshore (upwelling favorable) wind stress. At a smaller scale, we demonstrate the sensitivity of the QuikSCAT wind stress curl to coastal processes related to sea surface temperature (SST) mesoscale fluctuations by presenting a linear relationship between the curl and crosswind SST gradients. Despite the spatial and temporal sensitivity of the... |
| Tipo: Text |
Palavras-chave: Wind stress; Upwelling; SST-wind interactions. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00233/34412/32820.pdf |
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| Robertson, Franklin R.; Roberts, Jason B.; Bosilovich, Michael G.; Bentamy, Abderrahim; Clayson, Carol Anne; Fennig, Karsten; Schröder, Marc; Tomita, Hiroyuki; Compo, Gilbert P.; Gutenstein, Marloes; Hersbach, Hans; Kobayashi, Chiaki; Ricciardulli, Lucrezia; Sardeshmukh, Prashant; Slivinski, Laura C.. |
| Four state-of-the-art satellite-based estimates of ocean surface latent heat fluxes (LHFs) extending over three decades are analyzed, focusing on the interannual variability and trends of near-global averages and regional patterns. Detailed intercomparisons are made with other datasets including 1) reduced observation reanalyses (RedObs) whose exclusion of satellite data renders them an important independent diagnostic tool; 2) a moisture budget residual LHF estimate using reanalysis moisture transport, atmospheric storage, and satellite precipitation; 3) the ECMWF Reanalysis 5 (ERA5); 4) Remote Sensing Systems (RSS) singlesensor passive microwave and scatterometer wind speed retrievals; and 5) several sea surface temperature (SST) datasets. Large... |
| Tipo: Text |
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| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00654/76588/77737.pdf |
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| Blanke, Bruno; Speich, Sabrina; Bentamy, Abderrahim; Roy, Claude; Sow, Bamol. |
| The structure and patterns of variability of the southern Benguela coastal upwelling system are investigated with a high-resolution regional model forced by QuikSCAT winds over 1999-2003. The relevance of this global wind product is tested, at first, for the specific nearshore southeast Atlantic; then, the wind products are spatially or temporally degraded from the original 0.5 degrees daily fluxes and are used to diagnose the main scales of the surface dynamical forcing variability. Time resolution appears as a crucial factor in the wind stress to retrieve the patterns of interannual anomalies in sea surface temperatures in a good agreement with independent NASA Pathfinder observations. Various upwelling indices are also calculated in the model to study... |
| Tipo: Text |
Palavras-chave: High resolution model; Ai sea interaction; Coastal upwelling. |
| Ano: 2005 |
URL: http://archimer.ifremer.fr/doc/2005/publication-768.pdf |
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| Bentamy, Abderrahim; Grodsky, Semyon A.; Elyouncha, Anis; Chapron, Bertrand; Desbiolles, Fabien. |
| Surface winds (10 m equivalent neutral wind velocity) from scatterometer missions since 1992 to present require homogenization to meet the requirements for oceanic and atmospheric climate data records. Sources of differences between winds retrieved from different scatterometer measurements mainly arise from calibration/validation procedures used for each scatterometer and differences in measurement physics. In this study, we focus on the calibration/validation component of the European Remote Sensing Satellite (ERS)-1 and ERS-2 wind speed biases. ERS-1 and ERS-2 data, named as WNF products, are from the Institut Français de Recherche pour l'Exploitation de la MER (IFREMER). In addition to WNF data, the newly calibrated ERS-2 products provided by the... |
| Tipo: Text |
Palavras-chave: Scatterometer; Surface wind; Homogenization. |
| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00334/44536/44468.pdf |
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| Bentamy, Abderrahim; Croize-fillon, Denis; Perigaud, C.. |
| The new scatterometer Advanced SCATterometer (ASCAT) onboard MetOp-A satellite provides surface wind speed and direction over global ocean with a spatial resolution of 25 km square over two swaths of 550 km widths. The accuracy of ASCAT wind retrievals is determined through various comparisons with moored buoys. The comparisons indicate that the remotely sensed wind speeds and directions agree well with buoy data. The root-mean-squared differences of the wind speed and direction are less than 1.72 m/s and 18 degrees, respectively. At global scale, ASCAT winds are compared with surface winds derived from QuikSCAT scatterometer. The results confirm the buoy analyses, especially for wind speed ranging between 3 m/s and 20 m/s. For higher wind conditions.... |
| Tipo: Text |
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| Ano: 2008 |
URL: http://archimer.ifremer.fr/doc/00004/11549/8149.pdf |
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| Bentamy, Abderrahim; Mouche, Alexis; Grouazel, Antoine; Moujane, Abderrahim; Mohamed, Ait Ahmed. |
| Scatterometer surface wind speed and direction observations in combination with radiometer wind speeds allow to generate surface wind analyses with high space and time resolutions over global as well as at regional scales. Regarding scatterometer sampling schemes and physics, the resulting surface wind analyses suffer from lack of accuracy in areas near coasts. The use of the synthetic aperture radar (SAR) onboard the Sentinel-1A satellite attempts to address the enhancement of surface wind analyses issues. In this study, SAR wind speeds and directions retrieved from backscatter coefficients acquired in interferometric wide (IW) swath mode are used. Their accuracy is determined through comprehensive comparisons with moored buoy wind measurements. SAR and... |
| Tipo: Text |
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| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00464/57611/59848.pdf |
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| Bentamy, Abderrahim; Piolle, Jean-francois; Grouazel, Antoine; Danielson, R.; Gulev, S.; Paul, Frederic; Azelmat, Hamza; Mathieu, P. P.; Von Schuckmann, Karina; Sathyendranath, S.; Evers-king, H.; Esau, I.; Johannessen, J. A.; Clayson, C. A.; Pinker, R. T.; Grodsky, S. A.; Bourassa, M.; Smith, S. R.; Haines, K.; Valdivieso, M.; Merchant, C. J.; Chapron, Bertrand; Anderson, A.; Hollmann, R.; Josey, S. A.. |
| For over a decade, several research groups have been developing air-sea heat flux information over the global ocean, including latent (LHF) and sensible (SHF) heat fluxes over the global ocean. This paper aims to provide new insight into the quality and error characteristics of turbulent heat flux estimates at various spatial and temporal scales (from daily upwards). The study is performed within the European Space Agency (ESA) Ocean Heat Flux (OHF) project. One of the main objectives of the OHF project is to meet the recommendations and requirements expressed by various international programs such as the World Research Climate Program (WCRP) and Climate and Ocean Variability, Predictability, and Change (CLIVAR), recognizing the need for better... |
| Tipo: Text |
Palavras-chave: Ocean Heat Flux; Latent heat flux; Sensible heat flux; Ocean heat content; Scatterometer; Surface wind; Specfic air humidity; OceanSites; Remotely sensed data. |
| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00403/51403/53729.pdf |
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| Mestas-nunez, Alberto M.; Bentamy, Abderrahim; Katsaros, Kristina. |
| The seasonal and anomaly variability of satellite-derived weekly latent heat fluxes occurring over the global oceans during a 3-yr period (January 1996-December 1998) is investigated using EOF and harmonic analyses. The seasonal cycle of latent heat flux is estimated by least squares fitting the first three (annual, semiannual. and 4 month) harmonics to the data. The spatial patterns of amplitudes of these harmonics agree well with the Corresponding patterns for wind speed. The annual harmonic captures an oscillation that reflects high evaporation in late fall/early winter and low evaporation in late spring/early summer in both hemispheres. with larger amplitudes in the Northern Hemisphere over the western side of the oceans and significant phase... |
| Tipo: Text |
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| Ano: 2006 |
URL: https://archimer.ifremer.fr/doc/00004/11544/8148.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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| Quilfen, Yves; Bentamy, Abderrahim; Delecluse, P; Katsaros, K; Grima, N. |
| Uncertainties in the surface wind field have long been recognized as a major limitation in the interpretation of results obtained by oceanic circulation models. It is especially true in the tropical oceans, where the response to wind forcing is very strong on short time scales. The purpose of this paper is to show that these uncertainties can be greatly reduced by using spaceborne wind sensors that provide accurate measurements on a global basis.Surface winds over the global oceans have been measured by scatterometry since the launch of the European Remote Sensing Satellite (ERS-1) in August 1991 by the European Space Agency, Noordwijk, The Netherlands, and is currently provided by ERS-2, launched in April 1995. The ground track wind vectors are processed... |
| Tipo: Text |
Palavras-chave: Ocean model; Ocean surface; Scatterometer; Sea level. |
| Ano: 2000 |
URL: http://archimer.ifremer.fr/doc/00000/10501/9560.pdf |
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| Le Traon, Pierre-yves; Antoine, D.; Bentamy, Abderrahim; Bonekamp, H.; Breivik, L. A.; Chapron, Bertrand; Corlett, G.; Dibarboure, G.; Digiacomo, P.; Donlon, C.; Faugere, Y.; Font, J.; Girard-ardhuin, Fanny; Gohin, Francis; Johannessen, J. A.; Kamachi, M.; Lagerloef, G.; Lambin, J.; Larnicol, Gilles; Le Borgne, P.; Leuliette, E.; Lindstrom, E.; Martin, M. J.; Maturi, E.; Miller, L.; Mingsen, L.; Morrow, R.; Reul, Nicolas; Rio, Myriam; Roquet, H.; Santoleri, R.; Wilkin, J.. |
| The paper gives an overview of the development of satellite oceanography over the past five years focusing on the most relevant issues for operational oceanography. Satellites provide key essential variables to constrain ocean models and/or serve downstream applications. New and improved satellite data sets have been developed and have directly improved the quality of operational products. The status of the satellite constellation for the last five years was, however, not optimal. Review of future missions shows clear progress and new research and development missions with a potentially large impact for operational oceanography should be demonstrated. Improvement of data assimilation techniques and developing synergetic use of high resolution satellite... |
| Tipo: Text |
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| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00270/38094/36245.pdf |
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| Bentamy, Abderrahim; Ayina, Ludos-herve; Queffeulou, Pierre; Croize-fillon, Denis; Kerbaol, Vincent. |
| Several scientific programs, including the Mediterranean Forecasting System Toward Environmental Predictions (MFSTEP project), request high space and time resolutions of surface wind speed and direction. The purpose of this paper is to focus on surface wind improvements over the global Mediterranean Sea, based on the blending near real time remotely sensed wind observations and ECMWF wind analysis. Ocean surface wind observations are retrieved from QuikSCAT scatterometer and from SSM/I radiometers available at near real time at Meteo-France. Using synchronous satellite data, the number of remotely sensed data available for each analysis epoch ( 00: 00 h; 06: 00 h; 12: 00 h; 18: 00 h) is not uniformly distributed as a function of space and time. On average... |
| Tipo: Text |
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| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/publication-3528.pdf |
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| Pinker, R. T.; Bentamy, Abderrahim; Katsaros, Kristina; Ma, Y.; Li, C.. |
| Many studies have been undertaken to evaluate turbulent heat fluxes at the ocean-atmosphere interface; less was done on the total net heat flux. We will compare heat budgets at the ocean-atmosphere interface as derived from satellites and from blended products, compare them to in situ observations, identify the location of largest differences, and attempt to explain reasons for these differences. The results over the Atlantic Sector (50 degrees S-50 degrees N) for a 3 year period show that differences in the turbulent fluxes among two widely used approaches are overshadowed by differences in the radiative fluxes. While the maximum difference in sensible and latent heat fluxes can be about 30 W/m(2), the mean values for latent heat fluxes are -2.27 W/m(2)... |
| Tipo: Text |
Palavras-chave: Oceanic heat fluxes; Oceanic net heat fluxes; Ocean-atmosphere interface. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00186/29713/28119.pdf |
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| Registros recuperados: 39 | |
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