In the higher latitudes of the northern and southern hemispheres, permafrost, defined as soils that remain at or below 0ºC for more than two years, underlies virtually all human development. An estimated 50% of Canada's land mass has traditionally been classified as permafrost.
The impact of rising temperatures related to climate change, and accelerated economic development in these regions, increases the risk of permafrost related surface deformation to buildings, power, water, and transportation infrastructures as the land on which they are built begins to thaw.
Satellite-based radar and MDA's advanced Multi-Track HDS-InSAR processing techniques provide a means for monitoring large areas in remote locations. Permafrost poses challenges for InSAR monitoring due to the complex temporal deformation patterns caused by both seasonal surface fluctuations and long-term changes in permafrost thickness due to warmer temperatures. Permafrost affected areas experience significant seasonal decorrelation due to winter snow cover and subsequent melt related surface erosion, making accurate monitoring more of a challenge.
To address this issue MDA developed a method that combines and jointly processes two or more same-side geometry InSAR stacks to provide a high-temporal resolution estimate of surface deformation. The method allows for combining stacks from more than a single SAR sensor and for a combination of frequency bands.
Data collected and analysed for an area near the community of Umiujaq in northern Quebec includes scenes from RADARSAT-2, TerraSAR-X, and COSMO-SkyMed. MDA conducted multiple studies of the area using InSAR stack-based surface deformation estimates, comparing results from the three sensors individually, and all sensors combined. Surface deformation results for each sensor were similar, however, combining data from all three radar sensors produced the best spatial coverage of coherent targets. These studies demonstrate the utility of combining stacks from differing radar sensors and bands for Multi-Track HDS-InSAR deformation monitoring.
InSAR is a cost-effective and accurate means of measuring surface deformation at regular intervals and high spatial resolution on an ongoing basis, over extended areas of 10’s to 1000’s of square kilometres, making it well suited for monitoring remote permafrost affected areas including direct onitoring of affected infrastructure.