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The Cryosphere An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/tc-2017-208
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
14 Nov 2017
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal The Cryosphere (TC).
Melting and fragmentation laws from the evolution of two large southern ocean icebergs
Nicolas Bouhier1, Jean Tournadre1, Frédérique Rémy2, and Rozenn Gourves-Cousin1 1Laboratoire d’Océanographie Physique et Spatiale, IFREMER, Université Bretagne-Loire, Plouzané, France
2Laboratoire d’Etudes en Géophysique et Océanographie Spatiales, UMR 5566 | CNES - CNRS , Toulouse, France
Abstract. 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 correlation analysis between the observed volume loss of our two icebergs and environmental parameters highlights those most likely to promote fragmentation. Consequently, a bulk model of fragmentation depending on ocean temperature and iceberg velocity is established and is shown to be able to reproduce well the observed volume variations. Finally, the size distribution of the calved pieces is estimated using both altimeter data and visible images and is found to be consistent with previous studies as typical of brittle fragmentation processes. These results are valuable to account for a more realistic representation of the freshwater flux constrained by large icebergs in models.

Citation: Bouhier, N., Tournadre, J., Rémy, F., and Gourves-Cousin, R.: Melting and fragmentation laws from the evolution of two large southern ocean icebergs, The Cryosphere Discuss., https://doi.org/10.5194/tc-2017-208, in review, 2017.
Nicolas Bouhier et al.
Nicolas Bouhier et al.
Nicolas Bouhier et al.

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Short summary
The evolution of two large southern ocean iceberg in terms of area and thickness are used to study the melting and fragmentation laws of icebergs. The area and thickness are estimated by the mean of satellite images and radar altimeter data. Two classical formulations of melting are tested and a fragmentation law depending on the sea temperature and iceberg velocity is proposed and tested. The size distribution of the pieces generated by fragmentation is also estimated.
The evolution of two large southern ocean iceberg in terms of area and thickness are used to...
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