Stability of Antarctic ice shelves: A case study of the Roi Baudouin Ice Shelf, Dronning Maud Land, East Antarctica

• Main Author: Berger, Sophie
• Other Authors: Pattyn, Frank, Tison, Jean-Louis, Coheur, Pierre, Moholdt, Geir, Drews, R
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Universite Libre de Bruxelles 2017
• Subjects: Glaciologie; Télédétection; Sciences de la terre et du cosmos; Cartographie; Géographie physique; Ice shelf; Antarctica; sea-level rise; pinning point; basal mass balance; climate change; Antarctic; The Antarctic; East Antarctica; Dronning Maud Land; Buttress; Roi Baudouin; Antarc*; Ice Sheet; Ice Shelf; Ice Shelves
• Online Access: http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/258789; https://dipot.ulb.ac.be/dspace/bitstream/2013/258789/5/ContratDiBerger.pdf; https://dipot.ulb.ac.be/dspace/bitstream/2013/258789/4/Berger2017_PhD_final.pdf; https://dipot.ulb.ac.be/dspace/bitstream/2013/258789/3/Berger2017_TOC_final.pdf

The Antarctic ice sheet is increasingly contributing to sea-level rise because of accelerated mass losses at its floating extensions -- its ice shelves. By floating while remaining attached to the grounded ice sheet, ice shelves buttress (i.e. restrain) the inland ice in such a way that ice-shelf losses lead to accelerated ice discharge in the ocean. This thesis investigates the stability of Antarctic ice shelves -- so crucial for the stability of the entire ice sheet -- using the Roi Baudouin Ice Shelf (RBIS), Dronning Maud Land, East Antarctica, as a case study. The RBIS has remained relatively stable over the last millennia and presents various kilometre-scale features (pinning point, ice-shelf channels and englacial lakes) with potential impact on its present and future stability.We first derive a horizontal velocity field, combining interferometry and speckle tracking with Synthetic Aperture Radar images from ERS 1/2 and ALOS-PALSAR, respectively. The resulting velocities and associated shear-strain rates represent the most detailed fields, currently available for the RBIS and clearly resolve small-scale features of the RBIS: significant slow-down and shearing are observed upstream of a small pinning point and ice converges at ice-shelf channels. We then combine our flow field with high-resolution elevations from TanDEM-X to infer the Basal Mass Balance (BMB) of the RBIS. This method relies on mass conservation in a Lagrangian frame and enables us to finely detect spatial variability in the BMB. We show that the BMB of the RBIS varies substantially on sub-kilometre scales. Our technique is promising and could easily be applied more widely.Additionally, the flow field is used to investigate how considering/ignoring small pinning points in observations (geometry and velocities) impacts data initialisation of poorly known parameters (e.g. basal friction, ice viscosity) and subsequent ice-sheet modelling with BISICLES. We find that overlooking the pinning point in the bathymetry leads to erroneous ice-shelf ...