On the simulation and observation of the Bragg scattering in the JERS-1 SAR images of machine-planted rice fields in the Kojima, Okayama, Japan

The present paper describes the results of the JERS-1 SAR observation and analysis of the machine-planted rice fields in the Kojima district, Okayama, Japan. Five sets of simultaneous field data on the spatial distribution and the growth of rice plants were collected when the JERS-1 passed over the test site in 1998. The comparison of the SAR images and the ground-truth data shows the large variations of 20-25 dB in the image intensity; and these changes depend on the direction of plantation and the bunch separation. The enhanced backscatter is associated with the Bragg scattering caused by the lattice-type regularity of mechanically planted rice plants. A simulation study based on the physical optics theory is carried out by taking accounts of the measured randomness of bunch separation and assuming the random nature in the radar backscatter from each bunch. A fairly good agreement is obtained between the simulation and the observed image intensity. Two sets of Landsat TM data at different growth stages are also used to make semi-quantitative comparison with the field and SAR data