High resolution PolInSAR with the ground-based SAR (GB-SAR) System: measurement and modelling

摘要

Ground-based work is necessary for acomprehensive assessment of the operational potential andlimitations of PolInSAR in airborne and satellite SARapplications. A study is made of the performance and usefulnessof the UK’s Ground-Based SAR (GB-SAR) Outdoor System inhigh-resolution PolInSAR studies of vegetation using modelingresults. The facility provides fully-polarimetric L- through X-bandimagery down to a resolution of several wavelengths.However, the measurement process is slow in relation to pulsedsystems as it requires the antenna head to be mechanicallyscanned across an aperture. The PolInSAR technique requireshigh coherence between interferometric image pairs, and thelong data acquisition times raise the question of temporaldecorrelation. We developed two models incorporating motion, aphysics-based model and a signal processing model. The formerincorporates a PolInSAR crop simulator employing the distortedBorn approximation, applied to a simulated canopy of wheatplants based on field-collected physiological measurements. GB-SARsimulations of mature wheat canopies suffering a range ofwind-blown disturbances are examined for coherence stability.These calculations permit the analysis of the behaviour ofcoherence with system and canopy descriptive parameters, suchto quantify the suitability and performance of measurementenvironments for PolInSAR analysis. The models indicate thatclutter motion will degrade interferometric performance bothduring aperture formation, and between repeat-pass observation.However, we conclude that the GB-SAR system will be robust tosmall amounts of clutter motion and will serve as a suitable tool for PolInSAR experimental studies.