SHELF-MIX: Mapping Ocean Mixing Beneath Antarctic Ice Shelves

Antarctic ice shelves, the floating extensions of the Antarctic ice sheet, play a critical role in controlling Antarctica’s contribution to future sea-level rise by restraining the seaward flow of grounded ice from the continent’s interior. Over recent decades, the rate at which ice shelves in key sectors of Antarctica are being melted from below by the ocean has accelerated, increasing the flow of grounded ice into the ocean and contributing to sea-level rise. The magnitude of ice shelf basal melting is controlled by how quickly turbulent ocean mixing transfers heat and salt to the ice base. Direct measurements of this turbulent mixing are sparse, hampering our ability to understand the important ice-ocean processes that drive ice shelf basal melting.  

This project will exploit existing datasets and pan-Antarctic numerical models (e.g. tidal and ocean-circulation models) to generate and contextualise the first pan-Antarctic atlas of sub-ice shelf mixing. Specifically, we will seek to answer:  

• How do the rates of vertical turbulent mixing vary in space and time beneath different Antarctic ice shelves?  

• What are the key controls on this variability, including the role of large-scale ocean forcing (e.g. tides, stratification) and ice shelf topography?  

• How is the space-time variability in mixing and vertical heat fluxes related to space-time variability in basal melting?  

The results will provide fundamental understanding of the mixing processes and their variability that drive Antarctic ice shelf melting and sea-level rise and will be promoted widely to the scientific community for use in state-of-the-art numerical models.