Modeling Fast Ice in the Southern Ocean Using a Particle-Continuum Approach

Approximately 4% to 13% of sea ice remains stationary, forming a narrow band around Antarctica. This contrasts with the majority of sea ice, which drifts with winds and ocean currents as "pack ice." This stationary landfast sea ice, known as "fast ice," is anchored to the coastline or grounded by icebergs and has significant implications for the global climate. However, current global climate models poorly represent fast ice, casting doubt on their ability to make accurate future projections for this critical component.

To address this limitation, we have developed a prognostic fast-ice representation suitable for coupled climate models. Our approach introduces a novel coupling mechanism between sea ice and grounded icebergs. This mechanism incorporates feedback from subgrid-scale grounded iceberg particles into the sea ice rheology. Idealized test cases demonstrate that this method successfully simulates fast ice as well as coastal polynyas due to subgrid-scale iceberg grounding.