Remote control of Filchner-Ronne melt rates by the Antarctic Slope Current.

Christopher Bull1, Nicolas Jourdain2, Adrian Jenkins1, Irena Vankova3, Pierre Mathiot4, Paul Holland5, Ute Hausmann6 and Jean-baptiste Sallee7, (1)NERC British Antarctic Survey, Cambridge, United Kingdom, (2)CNRS - Université Grenoble Alpes - Institut des Géosciences de l'Environnement, Saint-Martin d’Hères, France, (3)Los Alamos National Laboratory, Los Alamos, United States, (4)Met Office, Exeter, United Kingdom, (5)British Antarctic Survey, Cambridge, United Kingdom, (6)Sorbonne Université, LOCEAN‐IPSL, CNRS/IRD/MNHN, Paris, France, (7)LOCEAN-IPSL, CNRS/IRD/MNHN/Sorbonne Université, Paris, France
The Filchner-Ronne Ice Shelf System (FISS) located at the southern boundary of the Weddell sea is the largest body of floating ice in the world, its tributary ice streams have a combined discharge of over 100 Gtons yr-1 or ~19% of the Antarctic continent. In the future, the FISS system then, has the potential to be a major component of Antarctica’s contribution to sea level rise. Future projections studies by Hellmer et al. (2012, 2017), suggest that the intrusion of warm circumpolar deep water could lead to dramatic, irreversible changes for the ice shelf system in the future. First-order questions remain however, as to the present day oceanographic factors influencing FISS’ melt rates. Improving our understanding of the relevant ocean processes surrounding FISS is crucial if we wish to provide accurate representations of the ice-shelf for future ocean ice-sheet coupled simulations.

In this study, we use eddy-permitting NEMO regional ocean model simulations with ice-shelves, to study the influence of changes in water properties of the Antarctic Slope Front on melt rates in FISS. Using ApRES observations collected by the British Antarctic Survey, we evaluate the mean and variability of the model melt rates. Contrary to previous work, we find that remote changes in salinity (not temperature) influence the mean FISS melt rate. We detail the pathway of the perturbed salinity, via the Antarctic Slope Front and show that the response is rapid, and transient, with a recovery time-scale of 5-15 years dependent on the size of the perturbation. We discuss how these results are relevant for hindcast simulations and future projections of FISS.