Weather and Climate Controls for Ocean Wave Corridors to Fast Ice and Ice Shelf Areas

Ocean wave impacts on Antarctic land fast ice and weakened ice shelf areas have been shown to initiate ice break-up, particularly when facilitated by warm and melt-saturated conditions on the ice. Here we examine several regions along the Antarctic coast with potentially vulnerable fast ice or ice shelf areas and explore the climate conditions that lead to low sea ice concentrations in the areas between the coastal ice and the open Southern Ocean. We call the areas leading to open ocean swell 'corridors'. Using the NSIDC sea ice concentration data set, we identify periods when ice cover is lowest in a few corridor areas. We then use a principal components analysis of sea ice concentration and climate reanalysis data (using NCEP reanalysis) to identify the conditions leading to low ice cover in the corridor regions.

The Larsen B embayment had a fast ice break-up event occur in January 2022 that led to loss of decade-old fast ice and subsequent re-activation of the ice tongue and glacier areas in the Larsen B. We show that strong westerly wind conditions, related to presence of a La Niña event in the Pacific and stronger Amundsen Sea Low, created a corridor in early 2022 that would permit open-ocean swell to reach the fast ice front. Similar relationships between fast ice break-up and open-water conditions are found for Porpoise Bay (Sabrina Coast), Getz-Sulzberger ice shelves, and southeastern Weddell Sea coast. Further work will examine wave height records to determine if breakups coincided with both low ice cover and a significant wave event in the corridor.