Analysis of Rice Growth Using Multi-Temporal Radarsat-2 Quad-Pol Sar Images

Three time series of quad-polarization RADARSAT-2 images have been acquired from transplanting to harvesting of rice crop. Ground truth data such as rice height and biomass etc. were measured during acquisition of RADARSAT-2 data in Hainan province, southern China. Among different observations, dry biomass and fresh biomass of rice crop have shown a temporal signature with a clear correlation with backscattering coefficient in HV/VH polarization, whose correlation parameters are mainly larger than 0.8, while HH and VV polarizations show unfavorable correlation with crop dry/fresh biomass, whose correlation parameters are lower than 0.6. Variations of scatter mechanism of rice crop from transplantation to maturity have been investigated based on Pauli decomposition and H/alpha/A-wishart classification. For Pauli decomposition, Pauli A component is the main backscatter of rice crop, which valued between 0.2 and 0.6 in the whole rice growth stage. Pauli B component ranks second, valued from 0.1 to 0.3. Pauli C component is low from 0.02 to 0.1. However, Pauli C component of rice crop shows the best correlation with days after transplantation. The experiment and analysis results show the quad-polarization RADARSAT-2 SAR data have great potential for monitoring rice growth. Furthermore, when rice crops are in reproductive or ripening stage, the SAR data can obtain good results for rice mapping. With the information of biomass and mapping area of rice, rice yield estimation can be made.