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| Titel |
Calving fluxes and melt rates of Antarctic ice shelves |
| VerfasserIn |
Mathieu A. Depoorter, Jennifer A. Griggs, Jan T. M. Lenaerts, Michiel R. van den Broeke, Jonathan L. Bamber |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250081867
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| Zusammenfassung |
| Iceberg calving has been assumed to be the dominant mass loss term for the Antarctic ice
sheet, with previous estimates of the calving flux exceeding 2,000 Gt yr-1. More
recently, the importance of melting by the ocean has been demonstrated close to the
grounding line and near the calving front. To date, however, no study has reliably
quantified the volume of bottom (sub-shelf) melt (BM) and the calving flux (CF) for the
whole of Antarctica. The distribution of freshwater in the Southern Ocean and its
partitioning between liquid and solid phase is, therefore, poorly constrained. Here, we
estimate the mass budget of Antarctic ice shelves using satellite measurements of
calving flux, grounding line flux and modelled ice shelf accumulation rates. We
obtain a total calving flux of 938Â ± 109 Gt yr-1 and a total net bottom melt of
1,130 ±Â 241 Gt yr-1. Thus, about half of the ice sheet surface mass gain is lost
through oceanic erosion before reaching the ice front and the calving flux is less
than half the estimate derived from iceberg tracking. Calving is therefore not the
most important term in the mass loss of the continent. In addition, the fraction of
mass loss from bottom melt varies dramatically from ~10 to 90% between ice
shelves. We find that ice shelves with high melt ratios correlate well with those
experiencing thinning and enhanced discharge, suggesting that a high melt ratio
may be a good indicator of ice shelf vulnerability to changes in ocean temperature. |
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