Sea ice break-up potential by locally generated wind waves in a polynya

Polynyas, regions of open water enclosed by sea ice, are persistent features near the Antarctic coast as well as in the pack ice. Waves are known to occur within polynyas. If a polynya is sufficiently separated from the “blue” Southern Ocean by pack ice, then it can be considered isolated from Southern Ocean waves. Wave energy in isolated polynyas must be generated locally. During offshore wind conditions, a polynya could provide a long fetch for waves to develop, and the wind-waves may be steep enough to break the ice pack from the inside outward. This is in contrast to the typical focus of wave-induced sea ice break-up from the outside-inward with waves originating from the Southern Ocean. Here, we present our investigation of this inside-out sea-ice erosion mechanism based on buoy measurements of waves in the Vincennes Bay Polynya, East Antarctica. The measurements confirm the presence of energetic locally generated waves, which appear to be sufficiently steep to break the ice at the polynya edge. Further, we evaluate the wave-induced sea-ice break-up potential in this recurring polynya over the past two decades. Our results confirm the importance of locally generated waves in Antarctic polynyas. This highlights the previously overlooked potential of waves to accelerate sea-ice loss from within the pack ice, contributing to the recent Antarctic sea-ice decline.