Dynamics of a barotropic current at an ice shelf front

Ice shelves in West Antarctica are melting at an increasing rate due to the flow of relatively warmCircumpolar Deep Water into the ice shelf cavities. The current that brings heat southward along theeastern side of a trough towards an ice shelf front is found to have a barotropic and a barocliniccomponent. Mooring observations in front of Getz Ice Shelf suggest that 90% (roughly 0.6 Sv) of thevolume transport and 65% of the temperature transport is linked to the barotropic component of thecurrent towards the ice shelf. It is unknown whether and how much of a barotropic current canpenetrate under the ice shelf across the about 300 m deep ice shelf front, where lines of constant watercolumn thickness discontinue.We conduct idealized modelling with MITgcm to investigate the dynamics of a barotropic current at theice shelf front. Friction and strong vertical velocities at the ice shelf front break the potential vorticityconstraint and allow the flow to partly enter the ice shelf cavity. Only a small fraction of the currentpenetrates deep into the cavity, while a strong current flows parallel to the ice shelf front, where basalmelt is largely enhanced. How much of the current enters the cavity and how far it reaches depends onthe ice shelf- and bedrock topography.