The impact of tides on Antarctic ice shelf melting

Abstract

Tides influence basal melting of individual Antarctic ice shelves, but their net impact on Antarctic-wide ice-ocean interaction has yet to be constrained. Here we quantify the impact of tides on ice shelf melting and the continental shelf seas using a 4gkm resolution circum-Antarctic ocean model. Activating tides in the model increases the total basal mass loss by 57gGtgyr-1 (4g%) while decreasing continental shelf temperatures by 0.04gg C. The Ronne Ice Shelf features the highest increase in mass loss (44gGtgyr-1, 128g%), coinciding with strong residual currents and increasing temperatures on the adjacent continental shelf. In some large ice shelves tides strongly affect melting in regions where the ice thickness is of dynamic importance to grounded ice flow. Further, to explore the processes that cause variations in melting we apply dynamical-thermodynamical decomposition to the melt drivers in the boundary layer. In most regions, the impact of tidal currents on the turbulent exchange of heat and salt across the ice-ocean boundary layer has a strong contribution. In some regions, however, mechanisms driven by thermodynamic effects are equally or more important, including under the frontal parts of Ronne Ice Shelf. Our results support the importance of capturing tides for robust modelling of glacier systems and shelf seas, as well as motivate future studies to directly assess friction-based parameterizations for the pan-Antarctic domain.