Monitoring Rice Phenology Based on Freeman-Durden Decomposition of Multi-Temporal Radarsat-2 Data

The target decomposition of polarimetric synthetic aperture radar (PolSAR) data was widely used to study the electromagnetic scattering properties of rice paddies. Many studies used eigenvectors-based decomposition like Cloude-Pottier decomposition to monitor rice growth but the potential of model-based decomposition like Freeman-Durden decomposition for rice phenology monitoring was not fully explored. Therefore, a rice phenology inversion method was presented in this paper using Freeman-Durden decomposition parameters acquired from multi-temporal, quad-polarization RADARSAT-2 data over rice fields in Meishan, China. A decision tree approach was employed for the retrieval algorithm. Results show that joint use of logarithmic power scattered by the surface scattering component and double-bounce scattering component of the covariance matrix provides a good performance and obtains a total accuracy of 89.7% when four phenological stages (i.e., transplanting, vegetative, reproductive, and maturation) are considered. Most of the errors occurred in the vegetative and reproductive stages. The corresponding errors were both 16.7%.