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| Registros recuperados: 43 | |
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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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| 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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| 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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| Tournadre, Jean. |
| Marine ecosystems are under increasing anthropogenic pressures from marine and terrestrial activities. Ship traffic, the major cause of change in the open ocean, and its temporal evolution are still largely unknown because of lack of data. Altimeter data provide a new powerful tool to detect and monitor the ship traffic through a method of analysis of echo waveform. The archive of seven altimeter missions has been processed to create a two decade database of ship locations. The estimated annual density maps compare well with the ones obtained from Automatic Identification System. The ship traffic analysis shows a global fourfold growth between 1992 and 2012, the largest increase being observed in the Indian Ocean and the Chinese seas reflecting the world... |
| Tipo: Text |
Palavras-chave: Altimetry; Ship traffic; Pollution; Anthropogenic pressure. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00229/34039/32432.pdf |
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| Bashmachnikov, I.; Carton, Xavier; Belonenko, T. V.. |
| In this work, we obtain new results on the manifestation of meddies (or of other deep eddies) at the sea-surface, further developing the results by Bashmachnikov and Carton (2012). The quasi-geostrophic equations are used to describe a near-axisymmetric vortex in the upper ocean, forced at its lower boundary by the isopycnal elevation of a moving meddy. The solution thus obtained provides a better approximation of the characteristics of meddy surface signals. The results show that in subtropics large meddies with dynamic radius R-m >30 km are always seen at the sea-surface with AVISO altimetry, that medium-size meddies with R-m = 20 km may be seen at the sea-surface only if they are sufficiently shallow and strong, while small meddies with R-m =10 km... |
| Tipo: Text |
Palavras-chave: Meddies; Surface signal; Altimetry. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00245/35615/34134.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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| 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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| Maraldi, Claire; Lyard, Florent; Testut, Laurent; Coleman, Richard. |
| A barotropic tidal model, with a parameterization term to account for the internal wave drag energy dissipation, is used to examine areas of possible M(2) internal tide generation in the Kerguelen Plateau region. Barotropic energy flux and a distribution of wave drag dissipation are computed. The results suggest important conversion of barotropic energy into baroclinic tide generation over the northern Kerguelen Plateau shelf break, consistent with a theoretical criterion based on ocean stratification, tidal forcing frequency, and bathymetric gradients. The sea surface height signatures of time-coherent internal tides are studied using TOPEX/Poseidon and Jason-1 altimeter data, whose ascending tracks cross nearly perpendicular to the eastern and western... |
| Tipo: Text |
Palavras-chave: Internal tides; Kerguelen Plateau; Altimetry; Barotropic tides. |
| Ano: 2011 |
URL: https://archimer.ifremer.fr/doc/00144/25564/23709.pdf |
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| Dibarboure, G.; Le Traon, Pierre-yves; Galin, N.. |
| Sea surface height (SSH) measurements provided by pulse-limited radar altimeters are one-dimensional profiles along the satellite's nadir track, with no information whatsoever in the cross-track direction. The anisotropy of resulting SSH profiles is the most limiting factor of mesoscale SSH maps that merge the 1D profiles.This paper explores the potential of the cross-track slope derived from the Cryosphere Satellite-2 (CryoSat-2)'s synthetic aperture radar interferometry (SARin) mode to increase the resolution of mesoscale fields in the cross-track direction. Through idealized 1D simulations, this study shows that it is possible to exploit the dual SARin measurement (cross-track slope and SSH profile) in order to constrain mesoscale mapping in the... |
| Tipo: Text |
Palavras-chave: Altimetry; Remote sensing; Sampling; Satellite observations; Interpolation schemes; Inverse methods. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00152/26305/24575.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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| 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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| Krug, Marjolaine; Tournadre, Jean; Dufois, F.. |
| Interactions between the Agulhas Current and the ecologically important region of the Agulhas Bank are studied through the analysis of high resolution along-track altimetry, merged mapped altimetry and in situ measurements of current speed and direction undertaken from a moored Accoustic Doppler Current Profiler (ADCP). Comparisons between current observations collected from the ADCP and the satellite altimeters are made to evaluate the validity of the analysis conducted on the altimetry. Both altimetry and in situ observations show that Natal Pulses are a major driver of variability along the eastern margin of the Agulhas Bank. On average, it is estimated that the circulation along the eastern margin of the Agulhas Bank is influenced by Natal Pulses for... |
| Tipo: Text |
Palavras-chave: Agulhas Current; Agulhas Bank; Natal pulse; Satellite oceanography; Altimetry. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00186/29676/28457.pdf |
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| Dibarboure, G.; Pujol, M. -i.; Briol, F.; Le Traon, Pierre-yves; Larnicol, Gilles; Picot, Nicolas; Mertz, F.; Ablain, M.. |
| For more than 13 years, the multisatellite DUACS system has been providing the altimetry community with Near Real Time and Delayed Time products ranging from reduced GDR (also known as CorrSSH) to along-track Sea Level Anomalies (SLA) and multimission Maps of Sea Level Anomalies (MSLA). A post-Jason-2 description of the DUACS system is given, with input data, processing and products, and a focus on the DT-2010 reprocessing involving a total of almost 60 years worth of altimetry data from GEOSAT to Jason-2. Less than one month after launch, Jason-2 proved to be a strong asset for multisatellite applications as it was able to replace Jason-1 as the reference mission in DUACS. Furthermore, the new Jason-2/Jason-1 tandem configuration provides an unprecedented... |
| Tipo: Text |
Palavras-chave: Jason-2; DUACS; Multimission; Altimetry; DFS; Cross-calibration; Reference mission; Jason tandem. |
| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00057/16791/14366.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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| Registros recuperados: 43 | |
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