Preprints
https://doi.org/10.5194/egusphere-2025-267
https://doi.org/10.5194/egusphere-2025-267
04 Feb 2025
 | 04 Feb 2025
Status: this preprint is open for discussion and under review for The Cryosphere (TC).

Spatio-temporal melt and basal channel evolution on Pine Island Glacier ice shelf from CryoSat-2

Katie Lowery, Pierre Dutrieux, Paul R. Holland, Anna E. Hogg, Noel Gourmelen, and Benjamin J. Wallis

Abstract. Ice shelves buttress the grounded ice sheet, restraining its flow into the ocean. Mass loss from these ice shelves occurs primarily through ocean-induced basal melting, with the highest melt rates occurring in regions that host basal channels – elongated, kilometre-wide zones of relatively thin ice. While some models suggest that basal channels could mitigate overall ice shelf melt rates, channels have also been linked to basal and surface crevassing, leaving their cumulative impact on ice-shelf stability uncertain. Due to their relatively small spatial scale and the limitations of previous satellite datasets, our understanding of how channelised melting evolves over time remains limited. In this study, we present a novel approach that uses CryoSat-2 radar altimetry data to calculate ice shelf basal melt rates, demonstrated here as a case study over Pine Island Glacier (PIG) ice shelf. Our method generates monthly Digital Elevation Models (DEMs) and melt maps with a 250 m spatial resolution. The data show that near the grounding line, basal melting preferentially melts a channel's western flank 50 % more than its eastern flank. Additionally, we find that the main channelised geometries on PIG are inherited upstream of the grounding line and play a role in forming ice shelf pinning points. These observations highlight the importance of channels under ice shelves, emphasising the need to investigate them further and consider their impacts on observations and models that do not resolve them.

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Katie Lowery, Pierre Dutrieux, Paul R. Holland, Anna E. Hogg, Noel Gourmelen, and Benjamin J. Wallis

Status: open (until 18 Mar 2025)

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Katie Lowery, Pierre Dutrieux, Paul R. Holland, Anna E. Hogg, Noel Gourmelen, and Benjamin J. Wallis
Katie Lowery, Pierre Dutrieux, Paul R. Holland, Anna E. Hogg, Noel Gourmelen, and Benjamin J. Wallis

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Short summary
We use CryoSat-2 to observe monthly changes in Pine Island Glacier's ice shelf (PIG) surface at 250 m resolution. We show that melt is focused on the western walls of basal channels and highlight the role of channels in grounding pinning points. PIG’s main channel geometry is inherited from the ice-bed interface upstream of the grounding line. These results highlight the importance of channels on ice shelf stability and how this can change over time.
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