Extraction and evaluation of polarimetric signature of various crop types using C-band and L-band fully polarimetric SAR data

Abstract

The polarimetric signature (PS) at two different crop-specific frequencies using fully polarimetric Radarsat-2 (C-band) and ALOS2/PALSAR2 (L-band) SAR data was generated and evaluated for crop and other dominant feature characterization. PS is a 3D-representation of the polarimetric information in different polarization bases that provides a better illustration of the target which is limited in the case of conventional methods. Differential response was observed at C- and L-band, surface scattering was dominant at L-band (cross-pol response of ~ 0.11) owing to its high penetration capability whereas at C-band (cross-pol response of ~ 0.25) volume component was found to be prevalent due to its extended interaction with crop canopy components. Also, variation in PS among the crop-types was observed at the same frequency. As the increase in Pedestal height (PH) can be attributed to multiple and/or volume scattering, for cotton high PH was noticed at C-band (0.28) than at L-band (0.11). Similarly, Paddy resulted in a PH of 0.22 and 0.09 at C-band and L-band respectively. The polarization signature for various crops (as was observed to be different) can be very useful in crop discrimination, parameters retrieval, and crop condition monitoring.