Mapping rice crop fields using C band polarimetric SAR data

The objective of this paper is to investigate the application of RADARSAT-2 polarimetric Synthetic Aperture Radar (SAR) data in mapping rice crop fields. Three RADARSAR-2 images of Fine Quad Polarization mode and rice biophysical parameters were collected synchronously in the early rice growth cycle in the test site in Guangdong Province in southern China. The temporal scattering mechanism of the rice field was analyzed by means of the Freeman and Durden three-component scattering model. The analysis shows that the flooded rice fields and moderate density of rice canopy in the ear differentiation period can produce higher double bounce scatter, higher phase difference of HH and VV measurements, and the Brewster angle effect tends to cause the significant drop of VV backscatter. Based on the result a method is proposed to map rice growing areas with high accuracy using only one RADARSAT-2 polarimetric SAR image. The results indicate the Freeman and Durden model can match the scattering features of rice crop quite well, and further demonstrate the advantages of C band polarimetric SAR in the SAR-based operational system for monitoring rice crop growth.