Observing Multidecadal Changes in Coastal Topography of Svalbard from Satellite Images

The warming in the Arctic has induced accelerated changes in coastal topography, such as the retreat of glaciers, thaw of permafrost, and increase of erosion and sedimentation along the coastline. A majority of Svalbard territory has been designated as natural reserves for numerous wildlife, especially on the west coast of Spitsbergen, which has seven locations listed as Ramsar Sites. Therefore, monitoring coastal dynamics is crucial for assessments of the climatic impact on those habitats. This study aims to utilize multiple satellite data, including Sentinel-1, Sentinel-2, and Landsat series to reconstruct time-varying digital elevation models (DEMs) over the intertidal zone of west Spitsbergen. The method includes the following steps: (1) classifying water in an image; (2) stacking images for inundation frequency; (3) converting frequency to elevation via a tide model; (4) repeating the workflow in a five-year temporal window. The latest DEM is verified by ICESat-2 spaceborne LiDAR ATL03 photons. Our preliminary results show that the accuracy of DEM, in terms of standard deviation, achieves 0.5 m level. Slight changes in coastal topography have been observed near Longyearbyen and other outlet glaciers.