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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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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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Detection of iceberg using Delay Doppler and interferometric Cryosat-2 altimeter data ArchiMer
Tournadre, Jean; Bouhier, Nicolas; Boy, F.; Dinardo, S..
The Cryosat-2 Synthetic Aperture Interferometric Radar Altimeter (SIRAL) altimeter is the first altimeter that can operate in three different modes over the ocean: the classical pulse limited LRM, the Delay Doppler or SAR and the SAR Interferometric modes. It offers a unique opportunity to test, validate and compare the capabilities of the three modes for the detection and analysis of small icebergs (<3 km in length) already demonstrated for classical altimeters. Over most of the sea-ice free ocean, SIRAL operates in LRM mode and the classical iceberg detection algorithm can be applied without modification. It can also be applied to the Reduced SAR or pseudo-LRM data computed from SAR and SARin data. In SAR mode, iceberg signatures are bright spots in...
Tipo: Text Palavras-chave: Small iceberg detection using Cryosat-2 three modes of operation; Estimation of iceberg's area; Estimation of iceberg's free-board from; Interferometric altimeter data.
Ano: 2018 URL: https://archimer.ifremer.fr/doc/00439/55089/56586.pdf
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Melting and fragmentation laws from the evolution of two large Southern Ocean icebergs estimated from satellite data ArchiMer
Bouhier, Nicolas; Tournadre, Jean; Remy, Frederique; Gourves-cousin, Rozenn.
The evolution of the thickness and area of two large southern ocean icebergs, having drifted in open water for more than a year, is estimated through the combined analysis of altimeter data and visible satellite images. Most of the iceberg modelling studies uses two main melting formulations that are compared with the observed thickness evolution of our two icebergs, to test their validity in case of large icebergs. The first formulation, based on a fluid dynamics approach, would tend to underestimate basal melt rates, so that using the second one (using a thermodynamic budget consideration) may be more relevant. Fragmentation is, before melting, the major decay process of large icebergs, yet it is a complex and still poorly documented mechanism. A...
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Ano: 2018 URL: http://archimer.ifremer.fr/doc/00410/52119/52827.pdf
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Etude de l'impact des icebergs Antarctiques sur l'Océan Austral ArchiMer
Bouhier, Nicolas.
The Antarctic polar ice cap constrains a freshwater flaux into the Austral Ocean through two equally important pathways : a localized and immediate injection through the melting of ice-shelves bases, and a delayed offshore injection through the calving and subsequent melt of icebergs. Some studies reckon that melting icebergs have the capacity to alter the hydrological and biogeo-chemical characteristics of the water column. The numerical models trying to evaluate this impact have shown contrasting results. Yet, they might suffer from a poor representation of the icebergs, namely due to our limited knowledge on both the spatial and size distributions of the icebergs, or even the processes involved in their mass loss. A new method using satellite altimetry...
Tipo: Text Palavras-chave: Ntarctique; Calotte polaire; Plate-forme glaciaire; Océan austral; Flux d’eau douce; Télédétection; Banquise; Fonte; Fracturation; Distribution de taille; Antarctica; Ice cap; Ice shelf; Southern Ocean; Iceberg; Freshwater flux; Remote sensing; Sea ice; Melting; Fragmentation; Fracturing; Size distribution.
Ano: 2017 URL: https://archimer.ifremer.fr/doc/00497/60905/64253.pdf
Registros recuperados: 5
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