Preprints
https://doi.org/10.5194/egusphere-2024-571
https://doi.org/10.5194/egusphere-2024-571
26 Mar 2024
 | 26 Mar 2024
Status: this preprint is open for discussion.

Calving of Ross Ice Shelf from wave erosion and hydrostatic stresses

Nicolas B. Sartore, Till J. W. Wagner, Matthew R. Siegfried, Nimish Pujara, and Lucas K. Zoet

Abstract. Ice shelf calving constitutes roughly half of the total mass loss from the Antarctic ice sheet. Although much attention is paid to calving of giant tabular icebergs, these events are relatively rare. More frequent, smaller-scale calving events likely play an important role in the ice shelf frontal dynamics. Here, we investigate the role of bending stresses at the ice shelf front in driving calving on the scale 100 m – 1 km, perpendicular to the ice edge. We focus in particular on how buoyant underwater "feet" that protrude beyond the above-water ice cliff may cause tensile stresses at the base of the ice and ultimately lead to fracture. Indirect and anecdotal observations of such feet at the Ross Ice Shelf front suggest that this process may be widespread. We consider satellite observations, together with an elastic beam model and a parameterization of frontal wave erosion to estimate the size and frequency of such calving events. Our results suggest that foot-induced mass loss at Ross Ice Shelf may cause up to 25 % of the total frontal ablation. However, stresses induced through this process are likely not sufficient to initiate crevassing but rather act to propagate existing crevasses. In addition, the relatively strong ice thickness dependence of the frontal uplift suggests an important role for internal bending moments due to temperature gradients in the ice. The highly variable environment, irregularity of pre-existing crevasse spacing, and complex rheology of the ice continue to pose challenges in better constraining the drivers behind the observed deformations and resulting calving rates.

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Nicolas B. Sartore, Till J. W. Wagner, Matthew R. Siegfried, Nimish Pujara, and Lucas K. Zoet

Status: open (extended)

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  • RC1: 'Comment on egusphere-2024-571', Ravindra Duddu, 10 Jun 2024 reply
Nicolas B. Sartore, Till J. W. Wagner, Matthew R. Siegfried, Nimish Pujara, and Lucas K. Zoet
Nicolas B. Sartore, Till J. W. Wagner, Matthew R. Siegfried, Nimish Pujara, and Lucas K. Zoet

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Short summary
We investigate how waves erode the front of Antarctica’s largest ice shelf, the Ross Ice Shelf, and how this erosion results in bending forces that can cause intermediate-scale calving (with icebergs of lengths ~100 m). We compare satellite observations to theoretical estimates of wave erosion and ice shelf bending to better understand the processes underlying this type of calving. We assess that these events may be responsible for roughly 25 % of the ice lost at the front of the Ross Ice Shelf.