DELINEATION OF DISCONTINUOUS PERMAFROST AT SCHEFFERVILLE USING RADARSAT IN INTERFEROMETRIC MODE

The coherence of interferometric synthetic aperture radar (InSAR) is adversely affected by snow added into the radar path between two successive imaging events. This feature of InSAR can be employed to map those parts of open terrain which do not retain snow at a given time of the winter. Differential InSAR can thus be used to identify areas where the difference between average long-term air and near-surface ground temperatures due to insulation by the snow cover is small. In locations where the average annual air temperature is below 0¼C, permafrost is usually present in those parts of the terrain where there is no snow retention. Two RADARSAT InSAR coherence images were computed for the Schefferville Digital Transect. These images show that areas which do not retain snow over the imaging interval can be identified. A comparison with a regional permafrost map produced by the Iron Ore Company of Canada (IOCC) shows a strong spatial correlation between the distribution of high-coherence zones and discontinuous permafrost.