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Abstract
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| We present a set of results obtained from georadar surveys carried out since 1999/2000 campaign, using radars of low (20-25 MHz) and high (200 MHz) frequencies on Johnsons and Hurd glaciers (Livingston Island, Antarctica). The radar records, together with other dynamical and geomorphological evidences, suggest that these glaciers have a polythermal structure, contrary to the usual assumption that glaciers on Livingston Island are temperate. The estimated ice volume of the Johnsons-Hurd ice cap is 0.968 ± 0.026 km³, for an area of 10.34 ± 0.03 km², with a mean ice thickness of 93.6 ± 2.5 m and a maximum of ca. 200 m. The subglacial topography was obtained combining the ice thicknesses data with the surface topography. The latter was measured using total station and differential GPS during 1999/2000 and 2000/2001, in a collaborative project with a research group of the Universitat de Barcelona. By comparing our data with the 1956 topography, constructed from aerial photographs taken by the British Antarctic Survey, we estimate that during the period 1956-2000 the volume of Johnsons-Hurd has decreased by 10.0 ± 4.5 %, which is equivalent to a sustained average annual mass balance of -0.23 ± 0.10 m w.e. By combining ice calving estimates with surface mass balance measurements, we observe that, in spite of sustained regional warming, the volume loss during the last decade has slowed down to values of -0.09 and -0.15 m w.e. for Johnsons and Hurd glaciers, respectively. | |
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International
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No |
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Congress
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7ª Asamblea Hispano Portuguesa de Geodesia y Geofisica |
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960 |
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Place
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San Sebastián |
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Reviewers
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Si |
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ISBN/ISSN
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Start Date
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25/06/2012 |
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End Date
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28/06/2012 |
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From page
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299 |
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To page
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299 |
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7ª Asamblea Hispano Portuguesa de Geodesia y Geofisica |