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| Registros recuperados: 43 | |
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| Dencausse, Guillaume; Arhan, Michel; Speich, Sabrina. |
| Using weekly sea surface height data Agulhas rings from the period October 1992 to December 2006 are detected and tracked from their formation dates and throughout the Cape Basin While 102 of them formed at the Agulhas Current retroflection their subsequent subdivisions and junctions led to 199 trajectories The rings geographical probability of presence shows two maxima One related to numerous ring passages lies in the submarine bight formed by the Erica seamount the Schmitt-Ott seamount and the northeastern tip of the Agulhas Ridge The other one to be ascribed to topographic blocking of the eddies is southeast of the latter obstacle On the basis of topographic effects three routes for Agulhas rings are distinguished a Northern route for rings that enter... |
| Tipo: Text |
Palavras-chave: Agulhas rings; Indo Atlantic exchanges; Altimetry. |
| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00019/13041/11315.pdf |
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| Verron, Jacques; Bonnefond, Pascal; Aouf, Lofti; Birol, Florence; Bhowmick, Suchandra A.; Calmant, Stephane; Conchy, Taina; Cretaux, Jean-francois; Dibarboure, Gerald; Dubey, A. K.; Faugere, Yannice; Guerreiro, Kevin; Gupta, P. K.; Hamon, Mathieu; Jebri, Fatma; Kumar, Raj; Morrow, Rosemary; Pascual, Ananda; Pujol, Marie-isabelle; Remy, Elisabeth; Remy, Frederique; Smith, Walter H. F.; Tournadre, Jean; Vergara, Oscar. |
| The India-France SARAL/AltiKa mission is the first Ka-band altimetric mission dedicated primarily to oceanography. The mission objectives were firstly the observation of the oceanic mesoscales but also global and regional sea level monitoring, including the coastal zone, data assimilation, and operational oceanography. SARAL/AltiKa proved also to be a great opportunity for inland waters applications, for observing ice sheet or icebergs, as well as for geodetic investigations. The mission ended its nominal phase after three years in orbit and began a new phase (drifting orbit) in July 2016. The objective of this paper is to highlight some of the most remarkable achievements of the SARAL/AltiKa mission in terms of scientific applications. Compared to the... |
| Tipo: Text |
Palavras-chave: Altimetry; Ka-band; Oceanography; Hydrology; Ice; Geodesy. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00600/71248/69623.pdf |
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| Siegelman, Lia; Klein, Patrice; Thompson, Andrew F.; Torres, Hector S.; Menemenlis, Dimitris. |
| Recent studies demonstrate that energetic sub-mesoscale fronts (10–50 km width) extend in the ocean interior, driving large vertical velocities and associated fluxes. However, diagnosing the dynamics of these deep-reaching fronts from in situ observations remains challenging because of the lack of information on the 3-D structure of the horizontal velocity. Here, a realistic numerical simulation in the Antarctic Circumpolar Current (ACC) is used to study the dynamics of submesocale fronts in relation to velocity gradients, responsible for the formation of these fronts. Results highlight that the stirring properties of the flow at depth, which are related to the velocity gradients, can be inferred from finite-size Lyapunov exponent (FSLE) at the surface.... |
| Tipo: Text |
Palavras-chave: Altimetry; Finite-size Lyapunov exponent; Ocean dynamics; Sub-mesoscale. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00645/75666/76532.pdf |
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| Louis, Gilles; Lequentrec-lalancette, Marie-françoise; Royer, Jean-yves; Rouxel, Didier; Géli, Louis; Maïa, Marcia; Faillot, Mathilde. |
| Over the past 3 decades, satellite altimetry has been a key tool for dynamic ocean studies and for accurately estimating sea surface heights. The geodetic reference surface—the “geoid”—can be approximated as the mean sea surface height of an ocean corrected for dynamic terms such as tides and currents. It is an equipotential surface of the gravity field; and variations of this field are quantified as free‐air anomalies, from which density heterogeneities of the oceanic basement can be inferred. Using such data in combination with other geophysical data, scientists have improved their knowledge of the nature of submarine relief and underlying structures. In solid Earth geophysics, major breakthroughs came from the development of high‐resolution marine... |
| Tipo: Text |
Palavras-chave: Altimetry; High resolution; SWAT soil and water assessment tool. |
| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00451/56260/57829.pdf |
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| Verron, Jacques; Bonnefond, Pascal; Andersen, Ole; Ardhuin, Fabrice; Bergé-nguyen, Muriel; Bhowmick, Suchandra; Blumstein, Denis; Boy, François; Brodeau, Laurent; Crétaux, Jean-françois; Dabat, Mei Ling; Dibarboure, Gérald; Fleury, Sara; Garnier, Florent; Gourdeau, Lionel; Marks, Karen; Queruel, Nadège; Sandwell, David; Smith, Walter H.f.; Zaron, Ed. |
| The CNES/ISRO altimetric satellite SARAL/AltiKa was launched in February 2013 and since then has provided useful data for various scientific and operational applications in oceanography, hydrology, cryospheric sciences and geodesy. However, a Reaction Wheel problem forced relaxation of the repeatability constraint on the satellite’s orbit, which has been drifting slowly since July 2016. Beyond the expected contributions of this mission and its very good integration into the objectives of the constellation of altimetric satellites, it has become more and more apparent that specific contributions and innovations related to the main specification of SARAL/AltiKa, that is to say the use of the Ka-band, have clearly emerged. The advantages of the Ka-band are in... |
| Tipo: Text |
Palavras-chave: Satellite; Altimetry; Ka-band. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00607/71878/70573.pdf |
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| Ardhuin, Fabrice; Brandt, Peter; Gaultier, Lucile; Donlon, Craig; Battaglia, Alessandro; Boy, François; Casal, Tania; Chapron, Bertrand; Collard, Fabrice; Cravatte, Sophie; Delouis, Jean Marc; De Witte, Erik; Dibarboure, Gerald; Engen, Geir; Johnsen, Harald; Lique, Camille; Lopez-dekker, Paco; Maes, Christophe; Martin, Adrien; Marié, Louis; Menemenlis, Dimitris; Nouguier, Frederic; Peureux, Charles; Rampal, Pierre; Ressler, Gerhard; Rio, Marie-helene; Rommen, Bjorn; Shutler, Jamie D.; Suess, Martin; Tsamados, Michel; Ubelmann, Clement; Van Sebille, Erik; Van Den Oever, Martin; Stammer, Detlef. |
| The Sea surface KInematics Multiscale monitoring (SKIM) satellite mission is designed to explore ocean surface current and waves. This includes tropical currents, notably the poorly known patterns of divergence and their impact on the ocean heat budget, and monitoring of the emerging Arctic up to 82.5°N. SKIM will also make unprecedented direct measurements of strong currents, from boundary currents to the Antarctic circumpolar current, and their interaction with ocean waves with expected impacts on air-sea fluxes and extreme waves. For the first time, SKIM will directly measure the ocean surface current vector from space. The main instrument on SKIM is a Ka-band conically scanning, multi-beam Doppler radar altimeter/wave scatterometer that includes a... |
| Tipo: Text |
Palavras-chave: Ocean current; Tropics; Arctic; Doppler; Altimetry; Sea state; Remote sensing; Ocean waves. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00498/60964/64372.pdf |
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| Tournadre, Jean; Bouhier, Nicolas; Girard-ardhuin, Fanny; Remy, F.. |
| Basal melting of floating ice shelves and iceberg calving constitute the two almost equal paths of freshwater flux between the Antarctic ice cap and the Southern Ocean. The largest icebergs (>100 km2) transport most of the ice volume but their basal melting is small compared to their breaking into smaller icebergs that constitute thus the major vector of freshwater. The archives of nine altimeters have been processed to create a database of small icebergs (<8 km2) within open water containing the positions, sizes, and volumes spanning the 1992–2014 period. The intercalibrated monthly ice volumes from the different altimeters have been merged in a homogeneous 23 year climatology. The iceberg size distribution, covering the 0.1–10,000 km2 range,... |
| Tipo: Text |
Palavras-chave: Iceberg; Altimetry; Southern Ocean. |
| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00307/41863/41114.pdf |
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| Qiu, Bo; Chen, Shuiming; Klein, Patrice; Sasaki, Hideharu; Sasai, Yoshikazu. |
| Located at the center of the western North Pacific Subtropical Gyre, the Subtropical Countercurrent (STCC) is not only abundant in mesoscale eddies, but also exhibits prominent submesoscale eddy features. Output from a 1/30 degrees high-resolution OGCM simulation and a gridded satellite altimetry product are analyzed to contrast the seasonal STCC variability in the mesoscale versus submesoscale ranges. Resolving the eddy scales of >150 km, the altimetry product reveals that the STCC eddy kinetic energy and rms vorticity have a seasonal maximum in May and April, respectively, a weak positive vorticity skewness without seasonal dependence, and an inverse (forward) kinetic energy cascade for wavelengths larger (shorter) than 250 km. In contrast, the... |
| Tipo: Text |
Palavras-chave: Circulation/ Dynamics; Eddies; Instability; Mesoscale processes; Observational techniques and algorithms; Altimetry; Models and modeling; Ocean models; Variability; Seasonal variability. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00245/35588/34142.pdf |
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| Tran, N; Tournadre, Jean; Femenias, P. |
| This letter provides validation results on both Envisat altimeter rain detection flag and rain rate estimates. This assessment was performed based on 18-month collocated data sets between Envisat with two sensor measurements from the Tropical Rainfall Measuring Mission, i.e., the microwave imager and the precipitation radar. Along with the comparison between closest sensor measurements with strict spatial and temporal criteria, discussion is also provided on environmental context insight when interpreting comparison results based on collocated data. |
| Tipo: Text |
Palavras-chave: Remote sensing; Rain; Radar cross sections; Altimetry. |
| Ano: 2008 |
URL: http://archimer.ifremer.fr/doc/2008/publication-4719.pdf |
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| Schlembach, Florian; Passaro, Marcello; Quartly, Graham D.; Kurekin, Andrey; Nencioli, Francesco; Dodet, Guillaume; Piollé, Jean-francois; Ardhuin, Fabrice; Bidlot, Jean; Schwatke, Christian; Seitz, Florian; Cipollini, Paolo; Donlon, Craig. |
| Radar altimeters have been measuring ocean significant wave height for more than three decades, with their data used to record the severity of storms, the mixing of surface waters and the potential threats to offshore structures and low-lying land, and to improve operational wave forecasting. Understanding climate change and long-term planning for enhanced storm and flooding hazards are imposing more stringent requirements on the robustness, precision, and accuracy of the estimates than have hitherto been needed. Taking advantage of novel retracking algorithms, particularly developed for the coastal zone, the present work aims at establishing an objective baseline processing chain for wave height retrieval that can be adapted to all satellite missions. In... |
| Tipo: Text |
Palavras-chave: Satellite altimetry; LRM; Delay-Doppler; Altimetry; SAR altimetry; Significant wave height; Round robin; Assessment; Comparison; Retracking; ESA; Climate change initiative. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00630/74172/73742.pdf |
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| Tournadre, Jean; Bouhier, Nicolas; Girard-ardhuin, Fanny; Remy, F.. |
| Large uncertainties exist on the volume of ice transported by the Southern Ocean large icebergs, a key parameter for climate studies, because of the paucity of information, especially on iceberg thickness. Using icebergs tracks from the National Ice Center (NIC) and Brigham Young University (BYU) databases to select altimeter data over icebergs and a method of analysis of altimeter waveforms, a database of 5366 icebergs freeboard elevation, length, and backscatter covering the 2002–2012 period has been created. The database is analyzed in terms of distributions of freeboard, length, and backscatter showing differences as a function of the iceberg's quadrant of origin. The database allows to analyze the temporal evolution of icebergs and to estimate a melt... |
| Tipo: Text |
Palavras-chave: Iceberg; Antarctica; Altimetry; Ice balance. |
| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00256/36719/35333.pdf |
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| Raj, R. P.; Halo, I.; Chatterjee, S.; Belonenko, T.; Bakhoday‐paskyabi, M.; Bashmachnikov, I.; Fedorov, A.; Xie, J.. |
| The interaction between the mesoscale eddies and the cyclonic gyre circulation of the Lofoten Basin is studied using a suite of satellite altimeters, a regional coupled ocean‐sea‐ice data assimilation system (the TOPAZ reanalysis) and Argo float data. An automated method identified 5,373/5,589 individual anticyclonic/cyclonic eddies in the Lofoten Basin from more than 65,000 altimeter‐based eddy observations, of which 70–85% are found to be nonlinear. The nonlinearity of eddies is estimated from its translational and rotational velocities. The study found clustering of highly intense nonlinear eddies on either side of the Lofoten Basin. Further, we show the distinct cyclonic drift of the anticyclonic and cyclonic eddies, both confined to the western side... |
| Tipo: Text |
Palavras-chave: Mesoscale eddies; Lofoten vortex; Lofoten basin; Gyre circulation; Altimetry; Argo floats. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00635/74707/74651.pdf |
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| Cardellach, Estel; Wickert, Jens; Baggen, Rens; Benito, Javier; Camps, Adriano; Catarino, Nuno; Chapron, Bertrand; Dielacher, Andreas; Fabra, Fran; Flato, Greg; Fragner, Heinrich; Gabarro, Carolina; Gommenginger, Christine; Haas, Christian; Healy, Sean; Hernandez-pajares, Manuel; Hoeg, Per; Jaggi, Adrian; Kainulainen, Juha; Khan, Shfaqat Abbas; Lemke, Norbert M. K.; Li, Weiqiang; Nghiem, Son V.; Pierdicca, Nazzareno; Portabella, Marcos; Rautiainen, Kimmo; Rius, Antonio; Sasgen, Ingo; Semmling, Maximilian; Shum, C. K.; Soulat, Francois; Steiner, Andrea K.; Tailhades, Sebastien; Thomas, Maik; Vilaseca, Roger; Zuffada, Cinzia. |
| The global navigation satellite system (GNSS) Transpolar Earth Reflectometry exploriNg system (G-TERN) was proposed in response to ESA's Earth Explorer 9 revised call by a team of 33 multi-disciplinary scientists. The primary objective of the mission is to quantify at high spatio-temporal resolution crucial characteristics, processes and interactions between sea ice, and other Earth system components in order to advance the understanding and prediction of climate change and its impacts on the environment and society. The objective is articulated through three key questions. 1) In a rapidly changing Arctic regime and under the resilient Antarctic sea ice trend, how will highly dynamic forcings and couplings between the various components of the ocean,... |
| Tipo: Text |
Palavras-chave: Polar science; GNSS; Reflectometry; GNSS-R; Sea ice; Altimetry; Polarimetry; Radio-occultation; Low Earth Orbiter. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00438/54994/56411.pdf |
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| Meyssignac, Benoit; Boyer, Tim; Zhao, Zhongxiang; Hakuba, Maria Z.; Landerer, Felix W.; Stammer, Detlef; Koehl, Armin; Kato, Seiji; L'Ecuyer, Tristan; Ablain, Michael; Abraham, John Patrick; Blazquez, Alejandro; Cazenave, Anny; Church, John A.; Cowley, Rebecca; Cheng, Lijing; Domingues, Catia M.; Giglio, Donata; Gouretski, Viktor; Ishii, Masayoshi; Johnson, Gregory C.; Killick, Rachel E.; Legler, David; Llovel, William; Lyman, John; Palmer, Matthew Dudley; Piotrowicz, Steve; Purkey, Sarah G.; Roemmich, Dean; Roca, Rmy; Savita, Abhishek; Von Schuckmann, Karina; Speich, Sabrina; Stephens, Graeme; Wang, Gongjie; Wijffels, Susan Elisabeth; Zilberman, Nathalie. |
| The energy radiated by the Earth toward space does not compensate the incoming radiation from the Sun leading to a small positive energy imbalance at the top of the atmosphere (0.4-1 Wm(-2)). This imbalance is coined Earth's Energy Imbalance (EEI). It is mostly caused by anthropogenic greenhouse gas emissions and is driving the current warming of the planet. Precise monitoring of EEI is critical to assess the current status of climate change and the future evolution of climate. But the monitoring of EEI is challenging as EEI is two orders of magnitude smaller than the radiation fluxes in and out of the Earth system. Over 93% of the excess energy that is gained by the Earth in response to the positive EEI accumulates into the ocean in the form of heat. This... |
| Tipo: Text |
Palavras-chave: Ocean heat content; Sea level; Ocean mass; Ocean surface fluxes; ARGO; Altimetry; GRACE; Earth Energy Imbalance. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00675/78723/80997.pdf |
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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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| Swart, Sebastiaan; Speich, Sabrina. |
| Swart et al. (2010) applied altimetry data to the gravest empirical mode south of Africa to yield a 16 year time series of temperature and salinity sections. In this study we use these thermohaline sections to derive weekly estimates of heat content (HC) and salt content (SC) at the GoodHope meridional transect of the Antarctic Circumpolar Current (ACC). These estimates compare favorably to observed data. The resulting 16 year time series of HC and SC estimates are used to explain the subsurface thermohaline variability at each ACC front and frontal zone. The variability at the Subantarctic Zone (SAZ) is principally driven by the presence of Agulhas Rings, which occur in this region approximately 2.7 times per annum and are responsible for the longest and... |
| Tipo: Text |
Palavras-chave: Altimetry; ACC; Fronts. |
| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00002/11307/7892.pdf |
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| Registros recuperados: 43 | |
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