Interannual Variation of Landfast Ice Using Ascending and Descending Sentinel-1 Images from 2019 to 2021: A Case Study of Cambridge Bay

Abstract

Landfast ice has undergone a dramatic decline in recent decades, imposing potentialeffects on ice travel for coastal populations, habitats for marine biota, and ice use for industries.The mapping of landfast ice deformation and the investigation of corresponding causes of changesare urgent tasks that can provide substantial data to support the maintenance of the stability of theArctic ecosystem and the development of human activities on ice. This work aims to investigate thetime-series deformation characteristics of landfast ice at multi-year scales and the correspondinginfluence factors. For the landfast ice deformation monitoring technique, we first combined the smallbaseline subset approach with ascending and descending Sentinel-1 images to obtain the line-of-sightdeformations for two flight directions, and then we derived the 2D deformation fields comprising thevertical and horizontal directions for the corresponding periods by introducing a transform model.The vertical deformation results were mostly within the interval [−65, 23] cm, while the horizontaldisplacement was largely within the range of [−26, 78] cm. Moreover, the magnitude of deformationobserved in 2019 was evidently greater than those in 2020 and 2021. In accordance with the availabledata, we speculate that the westerly wind and eastward-flowing ocean currents are the dominantreasons for the variation in the horizontal direction in Cambridge Bay, while the factors causingspatial differences in the vertical direction are the sea-level tilt and ice growth. For the interannualvariation, the leading cause is the difference in sea-level tilt. These results can assist in predicting thefuture deformation of landfast ice and provide a reference for on-ice activities.