Observing sea ice ridges and deformed sea ice from satellites in the Arctic

• Main Authors: Sandven, Stein, Babiker, Mohamed, Kloster, Kjell
• Format: Report
• Language: English
• Published: Zenodo 2007
• Subjects: Arctic; Sea ice; Monitoring; Ice ridges; Ice keels; Altimeter; Synthetic Aperture Radar; Image; Barents Sea; Canadian Archipelago; Greenland; Svalbard
• Online Access: https://doi.org/10.5281/zenodo.7540691

The objective of the study has been to assess capabilities and limitations of new earth observation satellites to detect and quantify sea ice ridges and other deformed sea ice types in the Arctic. Ridging and corresponding ice keels represent the thickest part of the sea ice cover. Detection and monitoring of ridges is therefore an important part of met-ice-ocean services to support operations in ice-covered seas. On large scale ridges can be observed by laser and radar altimeter data through a surface roughness parameter that is defined by standard deviation of the surface elevation measurements along the satellite orbit. The ICESat laser altimeter has provided experimental data over six weeks periods from 2003 to 2006. These data show clearly that the area north of Greenland and the Canadian Archipelago has the highest surface roughness of the Arctic sea ice and that firstyear ice has lower roughness than multiyear ice. This is in agreement with in situ observations and with aircraft laser measurements. On regional and local scale, satellite Synthetic Aperture Radar (SAR) images have been used to develop ridge detection methods over the last 10 – 15 years. Several studies of sea ice processes have been conducted in the Baltic Sea, the Barents Sea and Svalbard area, in the Russian Arctic and in Canadian waters, showing that SAR can be a useful tool to detect ridges and deformed ice. The advantage of the SAR is that it can be used to discriminate areas of deformed ice from areas of level ice. Also areas with hummocks, stamukhas and individual ridges of a certain width can be identified in SAR images. SAR image cannot provide any quantitative estimate of the height of ridges. This parameter can best be measured by laser altimeter. Use of SAR images with alternating polarization and high spatial resolution (better than 10 m) is expected to improve the classification of rough ice and detection of ridges. When SAR is used in combination with laser measurements from satellite or aircraft, the detection of ridges and ...