Derivation of Soil Surface Roughness Dynamics from Multi-temporal and Multi-parametric Air-borne PolSAR-data

The dynamics of soil surface roughness is important to a number of land surface processes. The potential of multi-temporal and multi-parametric PolSAR-data for soil surface roughness estimation is investigated to determine its temporal development. The study is based on weekly quadpol L-Band E-SAR backscatter data, which was collected over the agri-phenological cycle in the course of the AgriSAR 2006 campaign. For ground truthing, the soil surface roughness was measured using photogrammetric imaging techniques. Two ground truth roughness inidces (rms-height s, tortuosity index T_B) and three polarimetric roughness estimators (anisotropy A, circular polarization coherence gamma_RRLL and the real part of the circular polarization coherence Re_[RRLL]) were compared. While most of the comparison outlined weak correlations, best and sufficient results were obtained between s and Re_[RRLL]. Multi-temporal roughness maps were derived from this relationship, which are further affected by the presence and development of particular plants.