ERS and ENVISAT SAR coherence properties of boreal forests

摘要

Ers sar and envisat asar C-band long-term coherence is likely to be affected by strong decorrelation in forested areas. Nonetheless, under winter conditions it is possible that open areas and, to a lesser extent, sparse forests retain some coheience. For this purpose we formed 35 and 70-days either ERS SAR or ENVISAT ASAR winter coherence images for several test sites in Finland and Siberia. Because of temporal decorrelation, forests appear totally decorrelated whereas open areas present high coherence as long as the environmental conditions are stable with temperatures below the freezing point. Open areas with weak topography can still exhibit high coherence for perpendicular baselines up to 1 km. Compared to 1-day coherence the dependency of coherence upon stem volume decreased. These results suggest that foreston-forest mapping using ERS and ASAR repeat-pass winter coherence is feasible.