Wspólnotowy Serwis Informacyjny Badan i Rozwoju - CORDIS

SAR data for glacier firnline/mass balance change detection

The glacial firnline of the Svartisen Glacier has been detected using ERS II SAR and ENVISAT ASAR data from 1995 and up to today. The firnline is detected by first correcting the image backscatter intensity for topographic and geometric contributions using the Muhlmann backscattering model. Then we discriminate between firn and ice facies based on the backscatter intensity since frozen firn has higher backscatter than ice. Transects across different areas of the glacier were chosen based on requirements of smoothness of topography, precipitation zones, and the availability of field data for validation and comparison.

A substantial retreat of the firnline has been observed over the last few years. The equilibrium line derived from field measurements show a similar trend as the firnline changes but has much larger year-to-year variability. Thus, the firnline may be a better indicator of climate change than the equilibrium line due to the smaller variance.

The retreat of the firnline altitude is more rapid on Oostbreen than on Storglombreen that is located further west. A large change is observed on Engabreen, which is located furthest to the west of the Svartisen Glacier system, though this change may have been amplified by the local topography.

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NORUT Information Technology Ltd.
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