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Paper title Monitoring ice-calving at the Astrolabe glacier (Antarctica) with seismological and Sentinel-2 satellite data
Authors
  1. Floriane Provost EOST - Ecole et Observatoire des Sciences de la Terre, Institut Terre et Environnement de Strasbourg / CNRS - Université de Strasbourg Speaker
  2. Dimitri Zigone EOST - Ecole et Observatoire des Sciences de la Terre, Institut Terre et Environnement de Strasbourg / CNRS - Université de Strasbourg
  3. Jean-Philippe Malet CNRS / EOST - Ecole et Observatoire des Sciences de la Terre
  4. Emmanuel Le Meur Université Grenoble Alpes
  5. Clément Hibert EOST - Ecole et Observatoire des Sciences de la Terre, Institut Terre et Environnement de Strasbourg / CNRS - Université de Strasbourg
Form of presentation Poster
Topics
  • A9. Polar Science and Cryosphere
    • A9.04 Mass Balance of the Cryosphere
Abstract text Better understanding the global (e.g. ice mass balance, ice motion) and local (e.g. fissures and calving processes, basal melting, sea-ice interactions) dynamics of tidewater Antarctic outlet glaciers is of paramount importance to simulate the ice-sheet response to global warming. The Astrolable glacier is located in Terre Adélie (140°E, 67°S) near the Dumont d'Urville French research station. In January 2019, a large fissure of around 3km has been observed in the western shore of the glacier which could lead to a calving of ca. 28km2. The fissure has progressively grown until November 2021 when an iceberg of 20km2 was released by the glacier outlet.

The location of the glacier outlet at the proximity of the Dumont D’Urville French research station is an asset to collect in-situ measures such as GNSS surveys and seismic monitoring. Satellite optical imagery also provides numerous acquisitions from the early 1990 till the end of the 2021 thanks to the Landsat and Sentinel-2 missions.

We used two monitoring techniques: optical remote sensing and seismology to analyze changes in the activity of the glacier outlet. We computed the displacement of the ice surface with MPIC-OPT-ICE service available on the ESA Geohazards Exploitation Platform (GEP) and derived the velocity and strain rates from the archive of multispectral Sentinel-2 imagery from 2017 to end of 2021. The images of the Landsat mission are used to map the limit of the ice front to retrieve the calving cycle of the Astrolabe. We observe that the ice front is significantly advanced toward the sea (4 km) since September 2016 and such an extension is not observed in the previous years (since 2006) although minor calving episodes occurred. The joint analysis of the seismological data and the velocity and strain maps are discussed with the recent evolution of the glacier outlets. The strain maps show complex patterns of extension and compression areas with a seasonal increase during the summer months. The number of calving events detected in the seismological dataset significantly increased during 2016-2021 in comparison with the period 2012-2016. Since the beginning of 2021, both dataset show an acceleration. The number of calving events increased exponentially from June 2021 to the rupture in November 2021 and the velocity of the ice surface accelerate from 1 m.day-1 to 4 m.day-1 in the part of the glacier that detached afterward. This calving event is the first one of this magnitude documented at the Astrolabe.