Estimation of Flexural Strength of Arctic Sea in the Marginal Ice Zone Using the Depolarization Ratio of Sentinel-1

Abstract

The decline of Arctic sea ice in its extent and thickness has been one of the most apparent evidence of the on-going climate change. Notwithstanding wide concerns of the climate change, the development of the Northern Sea Route is considered to bring new economic opportunities as transporting through the Arctic is becoming feasible. Flexural strength of sea ice is the applied stress just before yielding and has been used in ship resistance test because icebreakers and ice-strengthened vessels break sea ice mostly by bending, weighting down on ice sheets. The flexural strength can be expressed as a brine volume fraction which strongly depends on salinity of sea ice. In this study, we try to develop an algorithm of extracting the flexural strength of sea ice using dual-polarimetric Sentienl-1 SAR data and salinity measurements from sea ice cores. The depolarization ratio of HH and HV polarization over the first year sea ice was sensitive to the bulk salinity which was measured from the cruises of IBRV Araon of Korea Polar Research Institute. The flexural strength of Arctic sea ice in the marginal zone in the north of Chukchi Sea and in the west of Beaufort Sea was estimated using the depolarization ratio of Sentinel-1 data. The results showed higher flexural strength for older ice when compared with the sea ice age map, which is distributed by NSIDC. The algorithm still needs further refinement using additional salinity measurements. The flexural strength of sea ice is expected to have commercial, navigational, and scientific contribution by providing near-real time sea ice information to the vessels and being used as a new sea ice index for monitoring climate changes.