Melting and fragmentation laws from the evolution of two large Southern Ocean icebergs estimated from satellite data

Type Article
Date 2018-07
Language English
Author(s) Bouhier Nicolas3, Tournadre Jean1, Remy Frederique2, Gourves-Cousin Rozenn1
Affiliation(s) 1 : Univ Bretagne Loire, Lab Oceanog Phys & Spatiale, UMR 6523, IFREMER,CNRS,IRD, Plouzane, France.
2 : CNES CNRS, Lab Etud Geophys & Oceanog Spatiales, UMR 5566, Toulouse, France.
Source Cryosphere (1994-0416) (Copernicus Gesellschaft Mbh), 2018-07 , Vol. 12 , N. 7 , P. 2267-2285
DOI 10.5194/tc-12-2267-2018
WOS© Times Cited 12

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

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