Satellite images and aerial photographs from the Arctic are beautiful to look at. The spatio-temporal changes which become visible when comparing multiple images, however, are not only very exciting visually but convey important scientific information on the stability of permafrost and changes in the northern the carbon cycle. The Siberian and Alaskan key study regions of the PETA-CARB project are geographically wide spread, geologically and climatically different, and cover a wide range of permafrost characteristics. In addition to their remoteness and difficult accessibility, all of them are vulnerable to rapid external disturbances due to the presence of very ice-rich permafrost close to the surface.
In our research, we apply different optical remote sensing methods for continuous monitoring of Arctic permafrost regions using a wide range of space and airborne image records. Spatial, temporal, spectral, and radiometric resolution determine the particular fields of application. Landsat data of medium spatial resolution are used for long-term and broad-scale time series analysis. Since adjacent orbits strongly overlap in northern high latitudes the temporal resolution of these data can be increased in order to derive robust trends of waterlogging, surface reflectance, and vegetation indexes. The very high repeat rate of the RapidEye satellite constellation, providing at the same time high spatial resolution and large areal coverage, allows capturing the strong seasonal variability of the Arctic tundra. Snow melt, lake ice out, and different phenological stages during only three summer months, as well as freeze back are being recorded year after year to obtain an understanding of the seasonal variability and to eventually differentiate long-term changes in the context with other data sets.