Simulating surface height and terminus position for marine outlet glaciers using a level set method with data assimilation
This work addresses the need for more accurate short-term predictions of ice sheet dynamics, particularly for marine outlet glaciers, which is crucial for climate modeling and sea-level rise projections, though it is incremental as it builds on existing methods.
The researchers tackled the problem of predicting glacier dynamics by implementing a data assimilation framework that integrates observations into an ice-flow model, demonstrating effectiveness in tracking seasonal and multi-year glacier advance and retreat cycles for an idealized glacier and more accurately simulating Helheim Glacier's terminus migration and surface changes.
We implement a data assimilation framework for integrating ice surface and terminus position observations into a numerical ice-flow model. The model uses the well-known shallow shelf approximation (SSA) coupled to a level set method to capture ice motion and changes in the glacier geometry. The level set method explicitly tracks the evolving ice-atmosphere and ice-ocean boundaries for a marine outlet glacier. We use an Ensemble Transform Kalman Filter to assimilate observations of ice surface elevation and lateral ice extent by updating the level set function that describes the ice interface. Numerical experiments on an idealized marine-terminating glacier demonstrate the effectiveness of our data assimilation approach for tracking seasonal and multi-year glacier advance and retreat cycles. The model is also applied to simulate Helheim Glacier, a major tidewater-terminating glacier of the Greenland Ice Sheet that has experienced a recent history of rapid retreat. By assimilating observations from remotely-sensed surface elevation profiles we are able to more accurately track the migrating glacier terminus and glacier surface changes. These results support the use of data assimilation methodologies for obtaining more accurate predictions of short-term ice sheet dynamics.