Estimation of high-resolution sea ice motion in the Arctic Ocean using Sentinel-1 images

Abstract

In order to better understand the rapidly changing marine environment and sea ice characteristics of the Arctic Ocean due to the continuous decreasing of sea ice, this study was carry out estimating the sea ice motion of the Arctic ocean in more detail using satellite data. The satellite data for the high-resolution sea ice motion used Sentinel-1 EW GRD SAR images with a spatial resolution of 40 m during 2015 to 2020 collected by the European Space Agency (ESA). For distinguishing the open sea and sea ice from satellite images, regression analysis and inflection detection were applied to the backscattering value of satellite images. The sea ice motion was calculated only in the area where sea ice was present by masking the area where the water was exposed. The sea ice motion retrieved from SAR images was obtained by Maximum Cross-Correlation (MCC) and Robust Optical Flow (ROF) methods using feature tracking of the paired images. Since the accuracy and the time required for calculating the sea ice motion are influenced by the size of the window set in the image, the most efficient window size was determined by the various window sizes. The high-resolution sea ice motion based on the SAR image was verified with the drift buoy data provided by the International Arctic Buoy Program (IABP) and the Ice-Tethered Profiler (ITP) and the medium-resolution sea ice motion data from the National Sea Ice Data Center (NSIDC). The difference of speed between drift buoys and high-resolution sea ice motion by MCC and ROF method are 0.0318 cm/s and 0.0971 cm/s averagely. When compared with the NSIDC's sea ice motion, difference of both methods are 0.8235 cm/s and 0.9505 cm/s, respectively. In addition, some NSIDC sea ice motion showed different moving pattern compared to drift buoys. It is believed to cause the low-spatial resolution. The high-resolution sea ice motion was more similar moving pattern of the drift buoy than that of the NSIDC.