Detection of Arctic icebergs on the base of satellite SAR
Vitaly Alexandrov(1), Vladimir Volkov(1), Stein Sandven(2), Mohamed Babiker(2) and Kjell Kloster(2)
(1) NIERSC, Vasilievsky Island, 14th line, 7, office 49, 199034, St. Petersburg, Russian Federation
(2) NERSC, Thormohlensgate 47, 5006 Bergen, Norway
Icebergs observed in the Eurasian Arctic are dangerous for navigation, oil and gas platforms and underwater communications, and therefore exploration of the Arctic shelf defines importance of their studies, as well as scientific interest. Icebergs, formed in the Eurasian Arctic, are calved from outlet glaciers, located in Svalbard, Franz Josef Land, Novaya Zemlya and Severnaya Zemlya, and are exported to the Arctic Basin, or to the south – to the Barents, Kara and Laptev Seas, where they melt during several years. These icebergs are significantly smaller than those in the Antarctic and Greenland. According to air reconnaissance data, in the Barents Sea their average length and width amounts to 103 m and 16 m, and maximum - 700 m and 50m.
Our study deals with iceberg identification from satellite high-resolution SAR and visible images. Analysis of their detection among open water, fast ice and drifting ice was performed, and features for their detection were revealed. A joint analysis of ENVISAT ASAR and “Monitor-E” images, as well as subsatellite observations showed that icebergs longer than 100 m could be reliably detected in open water and fast ice. The most complicated task is their recognition in drifting ice, because its backscatter varies depending on ice type, form, and other parameters. However, in several ERS, RADARSAT and ENVISAT SAR images icebergs were detected in the Laptev Sea, where their length amounts to several hundred meters. Their detection in the Barents Sea, where size of icebergs is less, is more ambiguous.
Based on conducted study, the methodology of iceberg detection in satellite images was elaborated. Combined use of different types of satellite information depending on ice and hydrometeorological conditions in the area under study, and successive image analysis allows significantly improve iceberg identification reliability. It was found that satellite high-resolution images allows obtaining more accurate estimates of their number than historical data, based on air reconnaissance and ship observations data.
Keywords: ESA European
Space Agency - Agence spatiale europeenne,
observation de la terre, earth observation,
satellite remote sensing,
teledetection, geophysique, altimetrie, radar,
chimique atmospherique, geophysics, altimetry, radar,