Extension of the Monte Carlo Coherent Microwave Scattering Model to Full Stage of Rice

The ear layer, which is a component of rice, is crucial to rice monitoring and yield estimation. By adding in the ear layer, we have extended the original coherent microwave scattering model, which is based on both the first-order solution of the radiation transfer equation and Monte Carlo numerical simulation methods, to full stage of rice. The detailed scene generation and the geometrical description of rice elements are presented. The propagation path of scattering in rice canopy is reduced. Two approximation methods are used to fit the curving ear by straight cylinders. Ground truth measurements of rice fields in heading stage, including the curvature of ear, were acquired extensively at Jinhu, Jiangsu in eastern China. Measured parameters are used in the new extended model to calculate the C-band backscattering coefficients of rice field. The simulation results are used for comparison with the backscattering coefficients extracted from RADARSAT-2 images to test the validity of the coherent scattering model with the mean absolute error reaching <; 3.3 dB in the copolarization mode. Theoretical analysis reveals that the ear morphology can largely affect the backscattering behavior of the rice field.