PermaSAR: Development of a Method to Detect Subsidence by Means of D-InSAR in Permafrost Regions
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The project PermaSAR aims at developing a novel method for detecting vertical movements of the topography in a low Arctic permafrost region in Canada, based on:
- ground-truth records (using a differential GPS and subsidence stations)
- terrestrial laser scanning (TLS) to assess the microtopography and low tundra vegetation
- RADAR data (TanDEM-X) for differential interferometry (D-InSAR)
- optical remote sensed data for further analysis and evaluations.
One quarter of the northern hemisphere is covered by permafrost and characterized by seasonal surface thawing (active layer). A warming of the permafrost temperatures has been observed for the last century in this region. Such warming provokes a deeper thawing layer during the summer months; this leads to severe consequences for the local population and the ecosystem. As these thawing and freezing processes of the permafrost are mainly responsible that streets break apart, buildings get cracks and potentially collapse, it is essential for science, economy and stakeholders (e.g. politics) to quantify these processes in order to identify potential subsidence areas (
early warning system) and to provide information to the local organization authorities to avoid severe damage.
The start of the TerraSAR-X/TanDEM-X satellites allows detecting fine-scale vertical surface movements by means of differential interferometry (D-InSAR). Previous studies showed the theoretical use of remote sensing data for such surface deformations, but also highlight limitations. The absolute values of vertical movements need improvement: Changing surface parameters (vegetation, microtopography and soil moisture) are also influencing the signal and masking the displacement information.
To overcome these limitations the aim of PermaSAR is to develop a multi-source methodology that improves the detection of vertical movements caused by thawing and freezing processes of the permafrost.
The project runs from April 2015 until March 2018. It is funded by the German Aerospace Center (DLR).