Impacts of bed topography resolution on sea-level rise projections from coupled subglacial hydrology and ice dynamics for Thwaites Glacier, Antarctica

Ice sheet models require explicit knowledge of the underlying bed. However, much remains unknown regarding the subglacial environment due to difficulties associated with measuring it. Extensive radar surveys have been conducted across Antarctica, but the requirement of full-coverage bed topography for models necessitates interpolation over gaps between existing observations, which often span kilometers or more. Advances in modeling capabilities now allow for the application of dynamic coupling between subglacial hydrology and ice dynamics in models of Antarctica. While a bed resolution of ~1 km is recommended for modeling Antarctic ice dynamics, it has been suggested that finer spatial resolutions are necessary to resolve subglacial water flow. We use a coupled model configuration to generate projections of glacier evolution, including the subglacial hydrologic system, for Thwaites Glacier, West Antarctica, initiated with several different bed topographies. We find that the specific bed topography has a first-order control on accumulated mass loss, but that final sea-level rise does not scale with bed resolution. We also find that coupling between subglacial hydrology and ice dynamics results in faster mass loss. Our results underscore the importance of continued high-resolution topography mapping and suggest that current projections may underestimate uncertainty linked to unresolved bed features.

Methods
This dataset includes the complete output from 9 simulations conducted using the Ice-sheet and Sea-level System Model (ISSM). The simulations explore variations in the representation of subglacial hydrology and bed topography resolution. Alongside the model outputs, we include all necessary files and code used to produce the figures presented in the manuscript.

Code/Software

This work was done using the Ice-sheet and Sea-level System Model (ISSM) and the Glacier Drainage System Model (GlaDS). GlaDS is implemented within ISSM, which is open access and available for download at https://issm.jpl.nasa.gov/. These scripts were run using ISSM version 4.24 and MATLAB version R2021b.