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Initial staging of code associated with Verboncoeur and others (2024) in Journal of Glaciology. Contact Hannah at hverboncoeur@mines.edu with questions. Data associated with this code can be found on Zenodo here. GitHub: https://github.com/hverboncoeur/Verboncoeur2024-JoG 

Abstract The ongoing deceleration of Whillans Ice Stream, West Antarctica, provides an opportunity to investigate the co-evolution of ice-shelf pinning points and ice-stream flux variability. Here, we construct and analyze a 20-year multi-mission satellite altimetry record of dynamic ice surface-elevation change (dh/dt) in the grounded region encompassing lower Whillans Ice Stream and Crary Ice Rise, a major pinning point of Ross Ice Shelf. We developed a new method for generating multi-mission time series that reduces spatial bias and implemented this method with altimetry data from the Ice, Cloud, and land Elevation Satellite (ICESat; 2003–09), CryoSat-2 (2010–present), and ICESat-2 (2018–present) altimetry missions. We then used thedh/dttime series to identify persistent patterns of surface-elevation change and evaluate regional mass balance. Our results suggest a persistent anomalous reduction in ice thickness and effective backstress in the peninsula connecting Whillans Ice Plain to Crary Ice Rise. The multi-decadal observational record of pinning-point mass redistribution and grounding zone retreat presented in this study highlights the on-going reorganization of the southern Ross Ice Shelf embayment buttressing regime in response to ice-stream deceleration. 

v2.0 of this dataset includes: All surface-elevation change (dh/dt) data from ICESat, CryoSat-2, and ICESat-2 altimetry missions necessary to reproduce figures and analysis from Verboncoeur et al. (2024) ('*dhdt_smb'); a file containing x,y positions of the ad-hoc reference tracks formed around ICESat ground tracks ('xy_is_masked.csv'); a folder containing delineated boundaries used in analysis ('SHAPES.zip'); folders containing raw subsetted ICESat data ('IS_data.zip') and a folder containing CryoCloud scripts for downloading ICESat-2 data ('IS2_processing_cryocloud.zip') 

Abstract Beneath Antarctica’s ice sheets, a little-observed network of liquid water connects vast landscapes and contributes to the motion of the overriding ice. When this subglacial water reaches the ocean cavity beneath ice shelves, it mixes with seawater, amplifying melt and in places forming deep channels in the base of the ice. Here we present observations from a hot-water-drilled borehole documenting subglacial water entering the ocean cavity at the grounding zone of Kamb Ice Stream and the Ross Ice Shelf. Our observations show that melt has removed approximately a third of the ice thickness, yet measurements reveal low rates of subglacial discharge in a turbid plume. Sediment cored from the channel floor shows larger discharge events occur and episodically deposit material from distinct geological domains. We quantify subglacial discharge and link our observations to the catchment upstream. We conclude that discrete discharge events are likely to dominate channel melt and sediment transport and result in the extensive ice-shelf features downstream of Kamb Ice Stream. 

Full version published with manuscript