Remote sensing of ice dynamics in the Beaufort Sea

Abstract

Arctic summer sea ice extent has undergone dramatic declines over the past several decades, particularly in the Beaufort Sea. The comprehension of the sea ice decline requires an understanding of the annual sea ice retreat during the summer melt season. While there are observations of the seasonal sea ice retreat, there is no accurate data on the evolution of sea ice thickness during the melt season. This thesis presents an analysis of sea ice in the Beaufort Sea using available sea ice freeboard data taken from NASA’s Ice, Cloud, and Elevation Satellite-2 (ICESat-2) mission. Through tracking bi-weekly changes in freeboard for Lagrangian tracked parcels of sea ice, the patterns of sea ice retreat are examined from 01 June – 30 September for 2020-2022. This method provides realistic patterns of sea ice thinning through mid-summer, with the most pronounced thinning occurring in the eastern Beaufort Sea. By September, freeboard changes are difficult to detect, with some subregions showing an increase in freeboard (thickening). The increase in freeboard likely reflects uncertainty due to changes in the distribution of ice types, particularly preferential disappearance of thinner ice but an also reduced rate of thinning. Although these results are preliminary, suggest that ICESat-2 can be used to track seasonal changes during the melt season to help identify trends and drivers of sea ice retreat. Further work is necessary to improve these results, especially in understanding how different ice types evolve. Other remote sensing data or in-situ observations are needed to reduce the uncertainty in the subregional estimates of ice melt.