以江苏省海安县为研究区,使用2008年获取的日本ALOS卫星PALSAR双极化模式数据,分析水稻在L波段SAR图像上的后向散射特征,并提出相应的水稻制图方法。水稻在L波段上表现出了和C波段相同的时相变化特征。HH极化后向散射依赖于水稻植株的空间分布结构,某些机械插秧区域的布拉格共振现象引起水稻后向散射严重增强,给利用PALSAR数据水稻制图带来了困难。而HV极化不存在布拉格共振现象。在考虑布拉格共振影响的条件下,提出了联合PALSAR双极化模式HH和HV极化数据、基于时相变化特征进行水稻制图的方法,获得了88.4%的制图精度。

Fine beam dual polarization data onboard Advanced Land Observing Satellite-Phased Array type L-band Synthetic Aperture Radar (ALOS PALSAR) for Hai'an, Jiangsu, China acquired in 2008 were used to analyze rice backscatter features at L-band SAR for the development of rice mapping method. Similar temporal change trend of backscatter was observed at L-band SAR to that of C-band. With the dependence of HH backscatter on the spatial distribution structure of the rice canopy, Bragg resonance scattering has been observed in some mechanically planted fi elds due to extremely enhanced backscatter, making it diffi cult to map rice using L-band SAR. However, the HV polarization is not subject to Bragg resonance. Considering the Bragg resonance effect in HH polarization, a rice mapping method was proposed based on the temporal change characteristics of backscattering coeffi cient by the synergistic use of HH and HV polarization images of ALOS PALSAR. A mapping accuracy of about 88.4% was achieved.