Dynamics of a barotropic current at an ice shelf front

Abstract

<p>Ice shelves in West Antarctica are melting at an increasing rate due to the flow of relatively warm<br>Circumpolar Deep Water into the ice shelf cavities. The current that brings heat southward along the<br>eastern side of a trough towards an ice shelf front is found to have a barotropic and a baroclinic<br>component. Mooring observations in front of Getz Ice Shelf suggest that 90% (roughly 0.6 Sv) of the<br>volume transport and 65% of the temperature transport is linked to the barotropic component of the<br>current towards the ice shelf. It is unknown whether and how much of a barotropic current can<br>penetrate under the ice shelf across the about 300 m deep ice shelf front, where lines of constant water<br>column thickness discontinue.<br>We conduct idealized modelling with MITgcm to investigate the dynamics of a barotropic current at the<br>ice shelf front. Friction and strong vertical velocities at the ice shelf front break the potential vorticity<br>constraint and allow the flow to partly enter the ice shelf cavity. Only a small fraction of the current<br>penetrates deep into the cavity, while a strong current flows parallel to the ice shelf front, where basal<br>melt is largely enhanced. How much of the current enters the cavity and how far it reaches depends on<br>the ice shelf- and bedrock topography.</p>