A new coupled ice-ocean model of the Amundsen Sea sector

The Amundsen Sea sector in West Antarctica has undergone dramatic changes recently, with increased ice loss, widespread thinning and retreating grounding lines. This has led to concerns about the future stability of the region and of the wider ice sheet, which could raise global mean sea level by several meters. Mass loss is predominantly driven by basal melting at the coast, where vulnerable ice shelves are exposed to warm ocean waters. However, internal ice dynamics also plays a huge role in how the ice sheet responds to ocean-induced melting. To understand the ice sheet evolution, we must consider changes in both the ice and ocean systems and how they affect each other.

Here we show preliminary results from a new coupled ice-ocean model of the Amundsen Sea sector. The model domain spans from the Abbot basin to the Getz basin, including the major Pine Island and Thwaites glaciers, and includes the continental shelf, break and open ocean. We use the ice-flow model Úa to produce a present-day configuration of the ice sheet, through a two-stage optimisation procedure involving observations of ice velocities and thickness changes. This is coupled offline to the MIT general circulation model, which includes both sea ice and ice shelf thermodynamics, and is forced with historical atmospheric conditions. The coupled model has been validated using both ice and ocean observations and will now be run using projected conditions. This new model will help us to better understand the complex interplay between ice dynamics and ocean conditions in the Amundsen Sea sector and what impact this will have in future scenarios.