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An altimetry-based gravest empirical mode south of Africa: 2. Dynamic nature of the Antarctic Circumpolar Current fronts ArchiMer
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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Antarctic icebergs distributions 1992-2014 ArchiMer
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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Anthropogenic pressure on the open ocean: The growth of ship traffic revealed by altimeter data analysis ArchiMer
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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Caracterização do meio físico da Bacia Hidrográfica do Rio da Prata, Mato Grosso do Sul. Infoteca-e
OLIVEIRA, H. de; COMAR, M. V..
Caracterização do meio físico; Localização; Altimetria; Solos; Recursos hídricos.
Tipo: Documentos (INFOTECA-E) Palavras-chave: Bacia hidrográfica; Solo; Altimetria; Recurso hídrico; Cerrado; Brasil; Mato Grosso do Sul; Bacia do Rio da Prata; Watersheds; Soil; Altimetry; Water resources; Brazil.
Ano: 2001 URL: http://www.infoteca.cnptia.embrapa.br/handle/doc/244621
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Characteristics of surface signatures of Mediterranean water eddies ArchiMer
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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Comparison between Eulerian diagnostics and finite-size Lyapunov exponents computed from altimetry in the Algerian basin ArchiMer
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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Defining a Sea Ice Flag for Envisat Altimetry Mission ArchiMer
Tran, N; Ardhuin, Fanny; Ezraty, Robert; Feng, H; Femenias, P.
This letter presents the development of a sea ice flag algorithm for the Envisat altimetry mission to detect sea ice corrupted sea surface height data within quality control processing. The algorithm takes advantage of having both passive and active microwave sensors on the same platform with coregistered measurements. Its performances have been evaluated based on collocations between the along-track Envisat data with reference maps built from combination of daily grids of sea ice concentration from SSM/I sensors and backscatter cross section from SeaWinds scatterometer on QuikSCAT satellite.
Tipo: Text Palavras-chave: Sea ice; Remote sensing; Microwave measurements; Altimetry.
Ano: 2009 URL: http://archimer.ifremer.fr/doc/2009/publication-5289.pdf
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Echanges indo-atlantiques d'eau subtropicale en relation aux structures frontales et de méso-échelle: Utilisation de la série temporelle altimétrique de niveau de la mer ArchiMer
Dencausse, Guillaume.
Indo-Atlantic exchanges of subtropical water play a crucial role in controlling global climate. The intense mesoscale activity south of Africa contributes to these exchanges, yet remains poorly described. A commonly accepted circulation scheme of those waters assmues that the subtropical gyres of the neighbouring oceans are partially connected, forming a super-gyre. Using an altimeter-derived sea-level time series spanning over 12 years, we study the exchanges through the "northern branch" of the super-gyre (Indian to Atlantic ocean), and through the "southern branch" (opposite direction). Regarding the northern branch, an initial study of the Agulhas Current Retroflection yields a statistical description of its behaviour, and shows the disrupting role of...
Tipo: Text Palavras-chave: Courant des Aiguilles; Anneaux des Aiguilles; Front Subtropical; Retroflection; Altimétrie; Échanges indo-atlantiques; Mésoéchelle; Agulhas Current; Agulhas Rings; 3subtropical Front; Retroflection; Altimetry; Indo-atlantic exchanges; Mesoscale.
Ano: 2009 URL: http://archimer.ifremer.fr/doc/00030/14091/11310.pdf
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Effect of long waves on Ku-band ocean radar backscatter at low incidence angles using TRMM and altimeter data ArchiMer
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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Etude de la variabilité de la circulation du gyre subpolaire de l'Atlantique Nord à partir des données Ovide et de mesures satellitaires ArchiMer
Gourcuff, Claire.
The cyclonic circulation of the North Atlantic subpolar gyre, between 50°N and 63°N, plays a key role in the climate variability. The Ovide program contributes to the observation of the circulation in this region. A section is repeated every two years in summer since 2002 between Greenland and Portugal following a path close the Fourex 1997 section. To get transport estimates across the sections, a geostrophic box inverse model is used, constrained with direct current measurements. Our new estimates of Fourex transports show the need to use constraints temporally associated with the section to get transports estimates representative of the circulation at the section realisation dates. It is also shown that altimetry velocities can be used instead of ADCP...
Tipo: Text Palavras-chave: Inverse Model; Courantology; Geostrophy; Altimetry; East Greenland Coastal Current; Freshwater fluxes; Heat transport; Meridionnal Overturning Circulation (MOC); Variability; North Atlantic; Subpolar gyre; Ovide; Modèle inverse; Géostrophie; Courantométrie; Altimétrie; Courant Côtier Est Groenlandais; Flux d'eau douce; Transport de chaleur; Circulation Méridienne de Retournement (MOC); Variabilité; Atlantique Nord; Gyre subpolaire; Ovide.
Ano: 2008 URL: http://archimer.ifremer.fr/doc/2008/these-6226.pdf
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Exploring the Benefits of Using CryoSat-2's Cross-Track Interferometry to Improve the Resolution of Multisatellite Mesoscale Fields ArchiMer
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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GNSS Transpolar Earth Reflectometry exploriNg System (G-TERN): Mission Concept ArchiMer
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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Impact des missions altimétriques et des réseaux de mesure in situ actuels et futurs sur l'analyse et la prévision océanique ArchiMer
Verrier, Simon.
Two series of Observing System Simulation Experiments (OSSEs) are carried out with global data assimilation systems at 1/4° and 1/12° resolution using simulated altimetry (satellite) and in situ (Argo  oat) data derived from a 1/12° resolution free run simulation. The objectives are to quantify how well di erent data sets can constrain a global data assimilation system. The positive impact of multiple altimeter data is clearly evidenced on sea level and ocean currents. The addition of Argo has a major impact to improve temperature and demonstrates the essential role of Argo together with altimetry to constrain a global data assimilation system. Results derived from these OSSEs are consistent with those derived from experiments with real data (observing...
Tipo: Text Palavras-chave: Océanographie; Systèmes opérationnels; Altimétrie; Flotte Argo; OSSE; OSE; Analyse; Prévision; 1/4°; 1/12°; Oceanography; Operationnal systems; Altimetry; Argo oat; OSSE; OSE; Analysis; Forecast; 1/4°; 1/12°.
Ano: 2018 URL: https://archimer.ifremer.fr/doc/00497/60915/64272.pdf
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Influence des ondes de Rossby sur le système biogéochimique de l'Océan Atlantique Nord: Utilisation des données satellites couleur de l'eau et d'un modèle couplé physique/biogéochimie ArchiMer
Charria, Guillaume.
The marine phytoplankton in the ocean represents only less than 1% of global biomass. Phytoplankton performs half of all photosynthesis. This autotrophic biomass in ocean is then an essential element in the climate regulation through processes as carbon dioxide absorption during the photosynthesis. Therefore, we need to estimate precisely this biomass as well as the processes which affect it. Using remotely sensed data (altimetry and ocean colour) and a coupled physical/biogeochemical model (MERCATOR-OPA/NPZDDON), Rossby waves and their influence on phytoplankton biomass are specifically studied in the North Atlantic Ocean. Their features and their influences on surface chlorophyll concentrations were analysed. Through the different mechanisms identified,...
Tipo: Text Palavras-chave: Coupled physical/biogeochemical modelling; Multi sensor wavelet analysis; Ocean carbon cycle; North Atlantic Ocean; Primary production; Ocean colour; Altimetry; Rossby (or planetary) waves; Planetary waves; Coupled physical/biogeochemical oceanography; Modélisaiton couplée physique/biogéochimie; Analyse en ondelettes multi capteurs; Cycle océanique du carbone; Océan Atlantique Nord; Production primaire; Couleur de l'eau; Altimétrie; Ondes de Rossby ou planétaires; Océanographie couplée physique/biogéochimie.
Ano: 2005 URL: http://archimer.ifremer.fr/doc/2005/these-2454.pdf
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Interactions between the Agulhas Current and the eastern margin of the Agulhas Bank ArchiMer
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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Jason-2 in DUACS: Updated System Description, First Tandem Results and Impact on Processing and Products ArchiMer
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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Large icebergs characteristics from altimeter waveforms analysis ArchiMer
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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Malvinas Current Volume Transport at 41 degrees S: A 24 Yearlong Time Series Consistent With Mooring Data From 3 Decades and Satellite Altimetry ArchiMer
Artana, Camila; Ferrari, Ramiro; Koenig, Zoe; Sennechael, Nathalie; Saraceno, Martin; Piola, Alberto R.; Provost, Christine.
We combined altimetric data and the in situ data sets from three 10 years apart mooring deployments to compute a coherent and accurate volume transport time series of the Malvinas Current (MC) at 41 degrees S. We used a method developed in Koenig et al. (2014) and explored three types of geostrophic shear to estimate the uncertainty derived from the lack of velocity data in the upper 300 m. The mean MC transport over 24 years in the upper 1,500 m is 37.12.6 Sv and the standard deviation 6.61 Sv. Since 1993, annual mean transports have varied from 32 to 41 Sv and the three in situ records corresponded to low annual mean transports. The MC transport time series is not stationary, its spectral content evolves with time showing significant energy at the 30-110...
Tipo: Text Palavras-chave: Malvinas Current; Transport; Time series; Altimetry; Moorings; Argentine Basin.
Ano: 2018 URL: https://archimer.ifremer.fr/doc/00481/59315/62076.pdf
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Monitoring of a quasi-stationary eddy in the Bay of Biscay by means of satellite, in situ and model results ArchiMer
Caballero, Ainhoa; Ferrer, Luis; Rubio, Anna; Charria, Guillaume; Taylor, Benjamin H.; Grima, Nicolas.
The presence of a quasi-stationary anticyclonic eddy within the southeastern Bay of Biscay (centred around 44°30′N-4°W) has been reported on various occasions in the bibliography. The analysis made in this study for the period 2003–2010, by using in situ and remote sensing measurements and model results shows that this mesoscale coherent structure is present almost every year from the end of winter-beginning of spring, to the beginning of fall. During this period it remains in an area limited to the east by the Landes Plateau, to the west by Le Danois Bank and Torrelavega canyon and to the northwest by the Jovellanos seamount. All the observations and analysis made in this contribution, suggest that this structure is generated between Capbreton and...
Tipo: Text Palavras-chave: Bay of Biscay; Eddies; SWODDIES; Topographic effects; Vortex; Mesoscale; Altimetry; Satellite oceanography; Drifters; ROMS.
Ano: 2014 URL: http://archimer.ifremer.fr/doc/00161/27260/25469.pdf
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New models for satellite altimeter sea state bias correction developed using global wave model data ArchiMer
Tran, N; Vandemark, D; Chapron, Bertrand; Labroue, S; Feng, H; Beckley, B; Vincent, Patrick.
Sea level determination via satellite altimetry is subject to numerous error sources. One of these is the sea state bias where changing surface wave conditions alter an altimeter's estimate of mean sea level. Recent work suggests that present day methods for correcting this bias, based solely on wave and wind information from the altimeter, may be improved if additional surface gravity wave field measurements become available. This paper tests this hypothesis by developing several new sea state bias correction models using a year long combination of Jason-1 data with wave field statistics generated from an hindcast of the WaveWatch3 ocean wave model. Each candidate model is produced in the same manner; through a nonparametric mapping between Jason-1 sea...
Tipo: Text Palavras-chave: Ocean wave model; Altimetry; Sea state bias.
Ano: 2006 URL: http://archimer.ifremer.fr/doc/2006/publication-1824.pdf
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