Combination of TerraSAR-X and Time-Lapse Photography for Snow on Sea-Ice Monitoring in Deception Bay, Nunavik

Abstract

Monitoring sea ice in Deception Bay (Nunavik, Hudson Strait) is not only relevant for local community members who rely on the fjord's rich ecosystem for subsistence in a context of a changing climate - lessons learned from this work have the potential to be applied in similar contexts elsewhere in Inuit Nunangat, and by other researchers studying the cryosphere. This work is part of the Safe Passage (Polar Knowledge Canada) project. In this study, we monitored snow-covered sea ice from freeze-up to break-up for three seasons of ice, combining three continuous time-series from frequent-revisit X-band SAR, hourly time-lapse photography, and air temperature measurements, from 2015 to 2018. TerraSAR-X high-resolution images have been acquired in three orbits (each every 11 days) since December 2015 and processed at DLR using the Multi-SAR System. Time-lapse cameras have been taking hourly pictures of the bay for the same period as well as measuring day time air temperature. This presentation will report on two contributions from TerraSAR-X data used in the study: 1) time-series which reproduce the SAR seasonal evolution for backscattering from snow-covered first-year sea ice already documented for the C-band, and 2) new observations for X-band backscattering over young ice types like grease ice, nilas, pancake ice, and grey-white ice. Seasonal features of the VV backscattering include a post-freeze-up peak, a monotone winter period with a slight negative trend, and a spring peak. The descending/morning and ascending/evening orbits were shown to behave differently in two periods: median winterly values and spring peak 2016. We propose that these differences in behavior are linked either to acquisition geometry (ascending or descending) or to acquisition time (evening or morning). This project is a collaboration with the Kativik Regional Government and is supported by Polar Knowledge Canada and the Raglan Mine.