Efficient flowline simulations of ice-shelf/ocean interactions: Sensitivity studies with a fully coupled model

Thermodynamic flowline and plume models for the ice-shelf/ocean system simplify the ice and ocean dynamics sufficiently to allow extensive exploration of parameters affecting ice-sheet stability while including key physical processes. Comparison between laboratory and geophysically based treatments of ice-ocean interface thermodynamics shows reasonable agreement between calculated melt rates, except where steep basal slopes and relatively high ocean temperatures are present. Results are especially sensitive to the poorly known drag coefficient, highlighting the need for additional field experiments to constrain its value. Our experiments also suggest that if the ice-ocean interface near the grounding line is steeper than some threshold, further steepening the slope may drive higher entrainment that limits buoyancy, slowing the plume and reducing melting; if confirmed, this will provide a stabilizing feedback on ice sheets under some circumstances.