Wetland Mapping in the West Siberian Lowlands with Envisat Asar Global Mode

Boreal peatland covers large areas on the northern hemisphere and thus plays an important role especially as carbon storage. Results from a range of microwave sensors have already shown a large potential for hydrological applications. We tested the ScanSAR system ENVISAT ASAR Global Mode (1km) time series for wetland monitoring in boreal environments. With a simple threshold method homogeneous peatland can be identified where backscatter and thus soil moisture is high during summer. In regions with abundant open water surfaces (permafrost transition zone) a different method needs to be applied. The mean backscatter during spring snowmelt is lower than for other landcover in this area. The location specific beginning and end of the snowmelt period was thus derived from Ku-Band scatterometer data (25 km, Quikscat) and used for the extraction of spring data from the Global Mode time series. The resulting dataset allowed the identification of up to 70% of peatlands in the reference database.