Effects of Ambient Currents on Melting at the Grounding Line

The stability of marine-terminating glaciers at the grounding line is critical for understanding the future of the West Antarctic Ice Sheet and its contribution to sea-level rise. While warm water intrusions are well-known drivers of ice-shelf melting, the role of shore-parallel ambient currents remains underexplored. Using a high-resolution, idealized MITgcm setup, we model a grounding zone cavity to investigate how along-shelf ambient currents influence circulation and melting patterns. Our results reveal that even modest ambient currents disrupt classical buoyancy-driven circulation by introducing Ekman layers and geostrophic flows that redistribute heat and salt. Positive along-shelf gradients amplify melting throughout the cavity, while negative gradients reduce melt rates, except near the grounding line. This dynamic interplay between ice-shelf and ambient currents significantly influences melt patterns and grounding-line stability. These findings emphasize the necessity of incorporating realistic three-dimensional ocean dynamics, including tides and residual circulation, into grounding-zone models. By linking shore-parallel flows, tides, and stratified ocean dynamics with melting processes, this study provides new insights into the retreat of Thwaites Glacier and underscores the critical role of small-scale ocean variability in ice-ocean interactions.