Publication Date:
2013-08-26
Description:
Frontal ablation from marine-terminating glaciers and ice caps covering the islands off the western coast of the Antarctic Peninsula is poorly known. Here we estimate the frontal ablation from the ice cap of Livingston Island, the second largest island in the South Shetland Islands archipelago, using glacier surface velocities obtained from intensity offset tracking of PALSAR-1 imagery and glacier ice thickness inferred from principles of glacier dynamics and calibrated against ground-penetrating radar (GPR) measurements of ice thickness. Using 21 SAR images acquired between October 2007 and January 2011, we obtain surface velocities of up to 250 m yr−1 and an average frontal ablation rate of about 509 ± 381 Mt yr−1, equivalent to a specific mass change of −0.7 ± 0.5 m w.e. yr−1 over the area of the ice cap (697 km2). A rough estimate of the surface mass balance of the ice cap gives 0.1 ± 0.1 m w.e. yr−1, resulting in a~total mass balance for Livingston Island ice cap of −0.6 ± 0.5 m w.e. yr−1. We find that frontal ablation and surface ablation contribute equal shares to total ablation. We also find large changes in frontal ablation rate (of ∼237 Mt yr−1) due to temporal variability in surface velocities. This highlights the importance of taking into account the seasonality in ice velocities when computing frontal ablation with a flux-gate approach.
Print ISSN:
1994-0432
Electronic ISSN:
1994-0440
Topics:
Geography
,
Geosciences
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