A novel finite element model for simulating fjord circulation

Basal melt of marine terminating glaciers is a key uncertainty in predicting the future climate and the evolution of the Greenland Ice Sheet. Detailed observations about the distribution of melt at Greenland’s glaciers and the ocean circulation in the adjoining fjords and specifically at the ice-ocean interface, are rare, due to the remoteness of the regions of interest. Hence, we rely heavily on models to get deeper insights into the processes in the fjords, underneath the ice shelves and at the ice-ocean interface. 

We present a novel Finite Element Model used to simulate the circulation in North Greenland's Sherard Osborn Fjord. Thanks to the finite elements the model can accurately represent fjord bathymetry and ice base geometry at the meter scale. A novel, symmetric, tensor-based viscosity formulation, using a residual-based method (residual viscosity), allows for high resolutions (meters) with minimal artificial viscosity and sharp gradients, while keeping computational times low. 

A high resolution representation of the sill in Sherard Osborn Fjord enables a more accurate simulation of the inflow of warm Atlantic Water towards the glacier. The more realistic representation of the ice base geometry and the high resolution allows us to model the distribution of melt rate underneath the ice shelf of Ryder Glacier in great detail, which can lead to better estimates of total melt rate. Furthermore, the high resolution and novel implementation of residual viscosity in the model enables an accurate simulation of the melt water plume with sharper gradients between the plume and the ambient water due to the absence of excess artificial viscosity and diffusivity.

In addition to the high resolution 2D simulations we are currently working on a 3D simulation using realistic ice base geometry and fjord bathymetry from Ryder Glacier and Sherard Osborn Fjord.