Bathymetric Control on Borchgrevink and Roi Baudouin Ice Shelves in East Antarctica

• Published in: Journal of Geophysical Research: Earth Surface
• Main Authors: Eisermann, Hannes, Eagles, Graeme, Ruppel, Antonia, Läufer, Andreas, Jokat, Wilfried
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Wiley 2021
• Subjects: Antarc*; Antarctica; Antarctica Journal; Dronning Maud Land; East Antarctica; Ice Sheet; Ice Shelf; Ice Shelves
• Online Access: https://epic.awi.de/id/eprint/54765/; https://epic.awi.de/id/eprint/54765/1/2021JF006342.pdf; https://doi.org/10.1029/2021JF006342; https://hdl.handle.net/10013/epic.d8d641c2-9cf2-43d4-85e2-5f05b1d82d6b

The stability of ice shelves and drainage of ice sheets they buttress is largely determined by melting at their atmospheric and oceanic interfaces. Subglacial bathymetry can impact ice shelf stability because it influences the onset and the pattern of warm ocean water incursions into the cavities between them and the seafloor. Bathymetry is further important at pinning points, which significantly retard the flow of ice shelves. This effect can be lost instantaneously if basal and surface melting cause an ice sheet to thin and lift off its pinning points. With all this in mind, we have developed a model of bathymetry beneath the western Roi Baudouin and central and eastern Borchgrevink ice shelves in Dronning Maud Land based on inversion from gravity data and tied to available depth references offshore and subglacial topography inland of the grounding line. The model shows deep glacial troughs beneath the ice shelves and bathymetric sills close to the continental shelf. The central Borchgrevink Ice Shelf overhangs the continental slope by around 50km, exposing its northern parts to the open ocean and higher ocean temperatures. Continuous troughs traverse the central Borchgrevink and western Roi Baudouin ice shelves at depths greater than the offshore thermocline and thus present a risk of Warm Deep Water intrusions into their cavities under the current and future oceanographic regimes. Differing bathymetric characteristics might explain the ice shelves' contrasting dominant mass loss processes.