RETRIEVAL OF RICE PHENOLOGY BASED ON TIME-SERIES POLARIMETRIC SAR DATA

Information of crop phenology is essential for evaluating crop productivity and crop management. Synthetic Aperture Radar (SAR), with the advantage of all-weather, day-night imaging and clouds penetrability, is an effective way for rice growth monitoring. In this study, we developed a method for remotely determining phenological stages of paddy rice with sixteen polarimetric SAR images. The method consists of three procedures: (I) Classified the transplanted rice (T-R) and the direct-sown rice (D-R) field; (II) Sensitivity analysis of polarimetric parameters versus rice phenology; (III) Reconstructing the time-series polarimetric parameters profiles of rice by time-frequency analysis; (IV) Specifying the phenological stages by detecting the maximum point, minimal point and inflection point from the smoothed polarimetric parameters time profile. Three keys phenological periods of rice were detected with the the accuracy of about 84%.