Abstract
AbstractAntarctica's ice shelves play a key role in stabilizing the ice streams that feed them. Since basal melting largely depends on ice‐ocean interactions, it is vital to attain consistent bathymetry models to estimate water and heat exchange beneath ice shelves. We have constructed bathymetry models beneath the ice shelves of western Dronning Maud Land by inverting airborne gravity data and incorporating seismic, multibeam, and radar depth references. Our models reveal deep glacial troughs beneath the ice shelves and terminal moraines close to the continental shelf breaks, which currently limit the entry of Warm Deep Water from the Southern Ocean. The ice shelves buttress a catchment that comprises an ice volume equivalent to nearly 1 m of eustatic sea level rise, partly susceptible to ocean forcing. Changes in water temperature and thermocline depth may accelerate marine‐based ice sheet drainage and constitute an underestimated contribution to future global sea level rise.
Highlights
Floating ice shelves in Antarctica play a key role in buttressing its grounded continental ice sheets
Bathymetry models for the Ekström and Atka ice shelves are based on aerogeophysical data collected during the austral summer of 2015/2016 within the Geodynamic evolution of East Antarctica (GEA) project conducted by the Alfred Wegener Institute (AWI) and Federal Institute for Geosciences and Natural Resources (BGR)
We have constructed new bathymetric models for seafloor beneath the Ekström, Atka, Jelbart, Fimbul, and Vigrid ice shelves using gravity inversions constrained by seismic, multibeam, and radar data and geological variability interpreted from magnetic anomalies
Summary
Floating ice shelves in Antarctica play a key role in buttressing its grounded continental ice sheets. Freezing and/or melting at ice shelf bases influences the overall mass balance of the ice sheets that feed them. The most important process by which Antarctica's ice shelves lose mass is basal melting by interactions with warm seawater (Depoorter et al, 2013; Oerter et al, 1992; Rignot et al, 2013), whose circulation beneath the shelves largely depends on subglacial bathymetry (An et al, 2019; Jenkins et al, 2010; Tinto et al, 2019). According to Goldberg et al (2019), accurate bathymetry is the leading requirement for correctly estimating basal melt rates in circulation models. Consistent and accurate bathymetric models benefit estimations of ice shelf and ice sheet stability. Most compilations of subglacial topography incorporate low‐resolution interpolated sub‐ice shelf bathymetries (Arndt et al, 2013; Fretwell et al, 2013; Morlighem et al, 2019)
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