Bed topography data gaps in the Antarctic Ice Sheet margin zone revealed by new analysis of Bedmap3 database for Antarctic RINGS.

Accurate bed topography is critical for predicting Antarctica's future ice discharge and sea-level contribution, yet large portions of the coastal ice sheet remain poorly mapped. We assessed radar-derived ice-thickness data coverage along the ice-sheet margin zone, focusing on dynamically sensitive sectors, using a 0.5 km grid and distance-to-data metrics. The study area encompassed a 100 km buffer from a simplified grounding line, including fast-flowing ice and regions where ISMIP6 experiments project grounding-line retreat by 2100. After filtering for GPS-quality data, over 41 million Bedmap3 measurements were analysed. Coverage varies widely across the 27 GSFC drainage basins: rapidly changing regions such as Thwaites and Pine Island glaciers are well sampled, whereas Enderby Land, Oates Land and the eastern Antarctic Peninsula exhibit gaps of 40-100 km. Ice rises and rumples are broadly undersampled despite their role in ice-shelf stability. These results provide an initial prioritization of targets for future airborne and helicopter-borne surveys. This prioritization is based primarily on existing data distribution and will be further refined through SCAR's RINGS Action Group regional efforts, ultimately supporting the development of next-generation Bedmap products. This article is part of the Theo Murphy meeting issue 'Next generation ice-sheet bed measurements'.