Episodic dynamic change linked to damage on the Thwaites Glacier Ice Tongue

Mapping Antarctic Crevasses and their Evolution with Deep Learning Applied to Satellite Radar Imagery

“…For example, a near flat signal is observed in fracture density near the grounding line of Thwaites Glacier Ice Tongue despite the large oscillatory changes observed over the last decade (Fig. 6 b, (Surawy-Stepney et al, 2023)). Similarly, the method is insufficient when regions undergo rapid fragmentation, for example during the disintegration of the seaward part of the Pine Island shear margin in 2020.…”

“…We define fracture density as the fracture maps integrated over an area of interest (Albrecht and Levermann, 2012;Surawy-Stepney et al, 2023) and use this as a heuristic measure of how crevassed that region is. We look for linear trends in this parameter over the observational period.…”

“…Additionally, surface crevasses can precondition ice shelves for disintegration via hydrofracture (Hughes, 1983;Rott et al, 1996;Scambos et al, 2009;Alley et al, 2018;Lai et al, 2020), can influence the surface energy balance of the ice sheet (Pfeffer and Bretherton, 1987;Purdie et al, 2022) and are a source of surface-to-bed hydrological pathways on grounded ice. Over the last decade, evidence has emerged that crevassing in the shear margins of fast-flowing ice shelves and ice streams can be of particular importance to the dynamics of the glacier (MacGregor et al, 2012;Lhermitte et al, 2020;Surawy-Stepney et al, 2023). In order to constrain theories regarding the role of fracturing in the evolution of the Antarctic Ice Sheet, a greater quantity of observational data is required.…”

“…More recently, Izeboud and Lhermitte (2023) showed the efficacy of a method of ice shelf fracture and orientation detection based on the application of radon-transforms to satellite images. Finally, previous work by Surawy-Stepney et al (2023) presented quantitative analysis of the structural properties of the Thwaites Glacier Ice Tongue using crevasse timeseries generated from Sentinel-1 SAR data using a neural network. This previous work forms the basis of the methods presented here.…”

“…to the grounding line and in the ice to the south of the eastern shear margin (black box, Fig.5 f). Fracturing on the central trunk has been increasing steadily over the observational period, while that in the eastern shear margin increases and decreases with acceleration of the main trunk, and has been shown to be linked to episodic ice dynamic behaviour of the ice tongue(Surawy- Stepney et al, 2023). Changes to fracturing in the regions closest to the grounding line have been periodic on timescales of a few years (Fig.6 b, d), so our linear trends do not capture the behaviour of this region in full.…”