Abstract
AbstractThe 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.
Highlights
Ice shelves play a major role in maintaining the stability of their respective ice sheets (e.g., Haseloff & Sergienko, 2018; Gudmundsson et al, 2019)
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
A good understanding of subglacial bathymetry is necessary for an improved knowledge of future ice shelf and ice sheet stability
Summary
Ice shelves play a major role in maintaining the stability of their respective ice sheets (e.g., Haseloff & Sergienko, 2018; Gudmundsson et al, 2019). If an ice shelf loses mass, the loss is balanced by an increased drainage of its linked ice sheet (Dupont & Alley, 2005). The balance can be forced toward mass loss by both atmospheric and oceanographic processes that deliver oceanic heat to ice shelf bases, which duly melt (Depoorter et al, 2013; Rignot et al, 2013). Knowledge of the bathymetry beneath the ice shelves has been shown to be crucial for estimating these basal melt rates (Goldberg et al, 2019; Tinto et al, 2015). A good understanding of subglacial bathymetry is necessary for an improved knowledge of future ice shelf and ice sheet stability
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