'Flashing Fields' in nearly simultaneous ENVISAT and ERS-2 C-band SAR images

摘要

Large differences are observed between radar backscatter measurements made by the ENVISAT and ERS-2 satellite synthetic aperture radars, within 30 min of each other over certain agricultural fields in Flevoland, The Netherlands. The differences appear to be caused by the presence of highly directive scattering combined with very small variations in the azimuth illumination angle of the two sensors at the degree or subdegree level. There is relatively little awareness of such sensitivity to illumination direction, and it is not predicted by models for microwave interaction usually applied to soils and vegetation. It is, however, to be expected if there are significant contributions from coherent scattering extending over patches of the agricultural fields in question. We present analysis that supports such a conclusion.