Surface dynamics and history of the calving cycle of the Astrolabe glacier (Antarctica) derived from optical imagery

• Main Authors: Provost, Floriane, Zigone, Dimitri, Meur, Emmanuel, Malet, Jean-Philippe, Hibert, Clément
• Format: Text
• Language: English
• Published: 2023
• Subjects: Astrolabe; Astrolabe Glacier; East Antarctica; Terre Adélie; Terre-Adélie; Antarc*; Antarctica; Sea ice
• Online Access: https://doi.org/10.5194/egusphere-2023-736; https://egusphere.copernicus.org/preprints/2023/egusphere-2023-736/

The recent calving of the Astrolabe glacier (Terre Adélie, East Antarctica) in November 2021 presents an opportunity to better understand the processes leading to ice fracturing. Optical satellite imagery is used to retrieve the calving cycle of the glacier since 2000 by mapping the ice front location. A recent archive of high resolution optical images from Sentinel-2 is used to measure the ice motion and the ice strain rates for the period 2017–2021 in order to document fractures and rift evolution. These observations are compared with sea ice extent and concentration measurements. We found that a significant change in the sea ice melting periodicity at the vicinity of the Astrolabe glacier occurred in the last decade (2011–2021) with respect to previous observations (1979–2011). After 2011, the occurrence of consecutive years of high sea-ice concentration at the vicinity of the glacier seems to have favored the ice tongue spatial extension. This lead to an unprecedentedly observed extension of the ice tongue until November 2021. The analysis of strain rate time series revealed that the glacier dislocated suddenly in June 2021 in the middle of the winter before releasing an iceberg of around 20 km 2 in November 2021 at the onset of sea ice melting season. These observations suggest that although the presence of sea ice favors glacier extension, its buttressing effect may not be sufficient to prevent fracture opening.