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| Registros recuperados: 22 | |
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| Tournadre, Jean; Ardhuin, Fanny; Legresy, Benoit. |
| Interest for icebergs and their possible impact on southern ocean circulation and biology has increased during the recent years. While large tabular icebergs are routinely tracked and monitored using scatterometer data, the distribution of smaller icebergs (less than some km) is still largely unknown as they are difficult to detect operationally using conventional satellite data. In a recent study, Tournadre et al. (2008) showed that small icebergs can be detected, at least in open water, using high resolution (20 Hz) altimeter waveforms. In the present paper, we present an improvement of their method that allows, assuming a constant iceberg freeboard elevation and constant ice backscatter coefficient, to estimate the top-down iceberg surface area and... |
| Tipo: Text |
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| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00083/19444/17050.pdf |
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| Ardhuin, Fanny; Ezraty, Robert; Croize-fillon, Denis. |
| Backscatter values from scatterometers are commonly used to estimate wind field over oceans, their ability to monitor sea ice coverage, age and drift has been also demonstrated. Here, ASCAT backscatter coefficient has been processed for sea ice geophysical interpretation in order to increase the long time series of ice parameters already available. It has been shown that incidence- adjustment is mandatory for geophysical meaning, the backscatter maps enable the discrimination between multi year ice and first year ice, these maps can also be used as a basic product for sea ice drift estimation. (Copyright : European Space Agency ISBN 978-92-9221-239-1 ISSN 1609-042X) |
| Tipo: Text |
Palavras-chave: Sea ice; Wind; Scatterometer; ASCAT; MetOp; Glaces de mer; Vent; Diffusiomètre; ASCAT; MetOp. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/2009/acte-6970.pdf |
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| Ardhuin, Fanny; Ezraty, Robert. |
| Satellites enable daily and global coverage of the polar oceans and provide a unique monitoring capability of sea ice dynamics. Sea ice drift maps can be estimated in Arctic from several satellite sensors, particularly from scatterometers and radiometers. This study presents the benefits of combining single drift fields at the same resolution into a "merged" field, built at three-and six-day lags during winters with a 62.5-km resolution. It is shown that combining these drift fields not only increases the reliability of the displacement estimation and the number of estimated vectors to almost a full ice covered area but also expands the time period over which these estimations are reliable from freeze until the melt onset. The autumn-winter-spring sea ice... |
| Tipo: Text |
Palavras-chave: Arctic; Advanced Scatterometer (ASCAT); Drift; Merging; Scatterometry; Sea ice. |
| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00088/19895/17729.pdf |
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| Ardhuin, Fabrice; Collard, Fabrice; Chapron, Bertrand; Ardhuin, Fanny; Guitton, Gilles; Mouche, Alexis; Stopa, Justin. |
| Swell evolution from the open ocean into sea ice is poorly understood, in particular the amplitude attenuation expected from scattering and dissipation. New synthetic aperture radar (SAR) data from Sentinel-1A wave mode reveal intriguing patterns of bright oscillating lines shaped like instant noodles. We investigate cases in which the oscillations are in the azimuth direction, around a straight line in the range direction. This observation is interpreted as the distortion by the SAR processing of crests from a first swell, due to the presence of a second swell. Since deviations from a straight line should be proportional to the orbital velocity toward the satellite, swell height can be estimated, from 1.5 to 5 m in the present case. The evolution of this... |
| Tipo: Text |
Palavras-chave: Ocean waves; SAR; Sea ice. |
| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00256/36718/35332.pdf |
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| Lique, Camille; Garric, Gilles; Treguier, Anne-marie; Barnier, Bernard; Ferry, Nicolas; Testut, Charles-emmanuel; Ardhuin, Fanny. |
| The authors investigate the variability of salinity in the Arctic Ocean and in the Nordic and Labrador Seas over recent years to see how the freshwater balance in the Arctic and the exchanges with the North Atlantic have been affected by the recent important sea ice melting, especially during the 2007 sea ice extent minimum. The Global Ocean Reanalysis and Simulations (GLORYS1) global ocean reanalysis based on a global coupled ocean sea ice model with an average of 12-km grid resolution in the Arctic Ocean is used in this regard. Although no sea ice data and no data under sea ice are assimilated, simulation over the 2001-09 period is shown to represent fairly well the 2007 sea ice event and the different components accounting for the ocean and sea ice... |
| Tipo: Text |
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| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00035/14637/11946.pdf |
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| Tournadre, Jean; Whitmer, K; Ardhuin, Fanny. |
| Small icebergs (edge lengths <1 km) are difficult to detect and track. In a recently published study, it was demonstrated that small targets (ships, islets,...) emerging from the sea can be detected by the analysis of high-rate altimeter waveforms. The analysis of Jason altimeter data revealed that small icebergs also have a detectable signature in the thermal noise part of the altimeter waveforms for open water. These signatures are very similar to that of transponders and are almost deterministic. An automated method based on the detection of parabolic shapes in the thermal part of the waveforms by analysis of the convolution product with a filter has been developed and applied to 1 year of Jason high-rate waveform data. In addition, the minimum... |
| Tipo: Text |
Palavras-chave: Antarctica; Iceberg; Altimeter waveform. |
| Ano: 2008 |
URL: http://archimer.ifremer.fr/doc/2008/publication-4530.pdf |
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| Ardhuin, Fanny; Ezraty, Robert. |
| The fourth International Polar Year (API) was officially launched at the Palais de la Découverte in Paris in the beginning of March. This international research effort will spread over two years. The polar specialists hope for an acceleration of the current programs, especially those dealing with the impact of climate warming on polar regions. Paul Tréguer, member of the French PAPI sponsoring committee, summarizes the different issues. And two Ifremer scientists explain how they've been observing, since 1992, the shrinking of the sea ice cover in the North Pole |
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| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/publication-6367.pdf |
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| Ardhuin, Fabrice; Tournadre, Jean; Queffeulou, Pierre; Ardhuin, Fanny; Collard, Fabrice. |
| The variability of small-size iceberg distributions is revealed from a novel analysis of satellite altimeter data. A strong annual cycle is modulated by pulse-like events confined to single ocean basins, with dense iceberg populations in the South Atlantic in 2004-2005, and in the South Pacific in 2008. Anomalies in sea surface temperatures of the order of 1 degrees C may be related to the iceberg distribution. Icebergs also appear very strongly associated with anomalies in the heights of ocean waves. A preliminary parameterization of wave blocking by icebergs significantly reduces wave model errors in the region south of 45 degrees South, and has a perceptible influence on all the west coasts of the Southern hemisphere. (C) 2011 Elsevier Ltd. All rights... |
| Tipo: Text |
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| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00044/15535/13317.pdf |
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| Ardhuin, Fanny; Mercier, G; Collard, F; Garello, R. |
| A methodology is proposed for the semiautomatic detection, characterization, and classification of slicks detected in C-band Synthetic Aperture Radar (SAR). For the first detection step, automatic algorithms were tested on Environmental Research Satellite (ERS) and Environmental Satellite (EnviSat) images acquired during the Prestige tanker accident. These tests reveal that simple filter or segmentation methods efficiently detect slicks with high contrasts and simple shapes, while a new and more complex multiscale method is able to detect a wider range of slicks. The characteristics of automatically detected slicks are then combined with meteooceanic data in order to eliminate slicks related to wind anomalies and current fronts. The data suggest that... |
| Tipo: Text |
Palavras-chave: Synthetic aperture radar SAR; Satellite measurement; Oil pollution; Image analysis. |
| Ano: 2005 |
URL: http://archimer.ifremer.fr/doc/2005/publication-1132.pdf |
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| Land, Peter E.; Findlay, Helen S.; Shutler, Jamie D.; Ashton, Ian; Holding, Thomas; Grouazel, Antoine; Ardhuin, Fanny; Reul, Nicolas; Piolle, Jean-francois; Chapron, Bertrand; Quilfen, Yves; Bellerby, Richard G.j.; Bhadury, Punyasloke; Salisbury, Joseph; Vandemark, Douglas; Sabia, Roberto. |
| Improving our ability to monitor ocean carbonate chemistry has become a priority as the ocean continues to absorb carbon dioxide from the atmosphere. This long-term uptake is reducing the ocean pH; a process commonly known as ocean acidification. The use of satellite Earth Observation has not yet been thoroughly explored as an option for routinely observing surface ocean carbonate chemistry, although its potential has been highlighted. We demonstrate the suitability of using empirical algorithms to calculate total alkalinity (AT) and total dissolved inorganic carbon (CT), assessing the relative performance of satellite, interpolated in situ, and climatology datasets in reproducing the wider spatial patterns of these two variables. Both AT and CT in situ... |
| Tipo: Text |
Palavras-chave: Carbonate chemistry; Earth observation; Ocean acidification; Total alkalinity; Dissolved inorganic carbon; SMOS; Aquarius; CORA; HadGEM2-ES. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00591/70267/68368.pdf |
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| Mercier, Grégoire; Ardhuin, Fanny. |
| Spaceborne synthetic aperture radar (SAR) is well adapted to detect ocean pollution independently from daily or weather conditions. In fact, oil slicks have a specific impact on ocean wave spectra. Initial wave spectra may be characterized by three kinds of waves, namely big, medium, and small, which correspond physically to gravity and gravity-capillary waves. The increase of viscosity, due to the presence of oil damps gravity-capillary waves. This induces not only a damping of the backscattering to the sensor but also a damping of the energy of the wave spectra. Thus, local segmentation of wave spectra may be achieved by the segmentation of a multiscale decomposition of the original SAR image. In this paper, a semisupervised oil-slick detection is... |
| Tipo: Text |
Palavras-chave: Water pollution; Synthetic aperture radar; Sea surface; Satellite applications; Oil spill; Image analysis. |
| Ano: 2006 |
URL: http://archimer.ifremer.fr/doc/2006/publication-1948.pdf |
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| Heygster, G.; Alexandrov, V.; Dybkjaer, G.; Von Hoyningen-huene, W.; Ardhuin, Fanny; Katsev, I. L.; Kokhanovsky, A.; Lavergne, Thomas; Malinka, A. V.; Melsheimer, C.; Pedersen, L. Toudal; Prikhach, A. S.; Saldo, R.; Tonboe, Rasmus; Wiebe, H.; Zege, E. P.. |
| In the Arctic, global warming is particularly pronounced so that we need to monitor its development continuously. On the other hand, the vast and hostile conditions make in situ observation difficult, so that available satellite observations should be exploited in the best possible way to extract geophysical information. Here, we give a resume of the sea ice remote sensing efforts of the European Union's (EU) project DAMOCLES (Developing Arctic Modeling and Observing Capabilities for Long-term Environmental Studies). In order to better understand the seasonal variation of the microwave emission of sea ice observed from space, the monthly variations of the microwave emissivity of first-year and multi-year sea ice have been derived for the frequencies of the... |
| Tipo: Text |
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| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00130/24174/22316.pdf |
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| Bailleul, Frédéric; Charrassin, Jean-benoit; Ezraty, Robert; Ardhuin, Fanny; Mcmahon, Clive R.; Field, Iain C.; Guinet, Christophe. |
| The behaviour of southern elephant seals from Kerguelen Island (4950′S, 7030′E) was investigated in relation to the oceanographic regions of the Southern Ocean. The oceanographic and the seal behaviour data, including location and diving activity, were collected using a new generation of satellite-relayed devices measuring and transmitting pressure, temperature, and salinity along with locations. Dive duration, maximum diving depth, time spent at the bottom of the dives, and shape of dive profiles were compared between male and female seals, and were related to the oceanographic characteristics of areas prospected by the seals. Most animals travelled to the Antarctic shelf. However, during winter, adult females travelled away from the... |
| Tipo: Text |
Palavras-chave: Mirounga leonina; Diving Behaviour; Pelagic environment; Benthic environment; Temperature profiles; Marine ecology. |
| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/publication-2500.pdf |
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| Registros recuperados: 22 | |
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