Arctic | Climate and Oceanography MASTER’S POSTER PRESENTATION Interferometric analysis of landfast sea ice breakouts occurring along the Alaska outer Continental Shelf Presenter: Andrew Einhorn , aheinhorn@alaska.edu, University of Alaska Fairbanks Andrew Mahoney , armahoney@alaska.edu, University of Alaska Fairbanks Landfast ice is sea ice that has become attached to the coast. During the winter months, landfast ice is relied upon by Indigenous coastal communities for substantive hunting of marine mammals commonly found at the boundary between landfast ice and open water. Breakout events pose a dangerous threat to the people who occupy the ice edge during hunting season due to the ice detaching from the coast without warning. The floe could drift away from the coast leaving the hunters stranded. Sea ice has been observed via Synthetic Aperture Radar Interferometry (InSAR) to deform plastically until failure in the form of a crack or breakout depending on the location and extent of stress within the ice. It is our hope that the interferogram prior to the breakout even captures this plastic deformation and could be used as an early warning for a breakout. To determine if InSAR analysis can be used to predict breakouts, we provide a comparison between the interferometric phase gradient observed from a 12-day interferogram directly preceding a breakout and the monthly average interferometric phase gradient. To do this we present monthly averages of the phase gradient from 12-day Sentinel-One interferograms for the 2018-2022 seasons. We then use Alaska Sea Ice Program (ASIP) ice charts to identify the date and location of breakout events. Using these data, we determine if the phase gradient was elevated prior to the breakout compared to the monthly average. Overall, we find the monthly average phase gradient to increase as the extent of the landfast ice increased. In addition, the phase gradient of the landfast ice that is part of a breakout is elevated compared to the monthly average. This analysis provides the foundation for using an elevated interferometric phase gradient as an indication that a breakout is likely in the near future.
Alaska Marine Science Symposium 2023 120
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