InSAR and Field Monitoring of Seasonal Solifluction Dynamics in Central Svalbard
Lauknes, Tom R.¹; Eckerstorfer, Markus¹; Christiansen, Hanne H.²; Larsen, Yngvar^1
1Norut, NORWAY; ²University Centre in Svalbard (UNIS), NORWAY

Solifluction is a mass wasting process occurring on shallow sloping areas in periglacial landscapes. Sediment moves slowly downslope due to recurrent frost heave by volumetric ice expansion and thaw settlement, accompanied by a gravitational downslope vector. Solifluction rates of up to a few cm/year are common, and the rates are dependent on active layer processes and meteorological conditions influencing the ground thermal regime. Thus by monitoring solifluction with its seasonal and interannual variability, the influence of global climate change can be determined. Presently, such efforts are restricted to expensive and time consuming point field measurements and some modeling efforts.

In order to upscale onto landscape scale, we combine for the first time detailed site scale geomorphological field process observations with remote sensing data covering at landscape scale. We apply the small baseline subset (SBAS) time-series InSAR method using TerraSAR-X SAR data to monitor seasonal ground deformation. The shorter wavelength of X-band combined with the high spatial resolution and short revisit time of 11 days is well-suited for monitoring the fine-scale displacement that happens during the freezing in autumn and the thawing in summer of the active layer above the permafrost. The TerraSAR-X satellite provides data with 11 days repeat cycle, enabling us to prepare for the Sentinel-1 a/b satellites, which will provide operational InSAR products with a repeat cycle of 12 days (or 6 days with both satellites).

In this work, we compare hourly field monitoring data between 2008-2011 of solifluction at Kapp Linné, central Svalbard with InSAR deformation time–series. Our results show that the InSAR method with temporal and spatial high-resolution TerraSAR-X data is able to pick up the seasonal deformation patterns of frost heave, ground settlement and associated solifluction. These results are a first step towards upscaling periglacial point field measurements to landscape scale.