玉米地微波相干和非相干散射模型比较分析

目的]对玉米地微波相干和非相干散射模型进行比较分析。方法]在Stile相干散射模型的基础上提出了针对玉米作物的相干散射模型,模型中使用物理光学(PO)和无限长介电圆柱体近似方法计算玉米叶片和秆的单散射体矩阵,替代了原模型中计算窄叶的单散射体模型,并在模型中考虑了不同散射机制之间相互作用所产生的相干分量。研究中所使用的非相干散射模型为密歇根森林散射模型(MIMICS)。使用吉林省公主岭地区玉米地部分生长周期内的实测数据为以上相干和非相干散射模型的输入参数,分别模拟L和C波段VV和HH极化的后向散射系数,并将这2个模型的模拟结果进行了比较。结果]该相干散射模型在L波段的模拟结果较差,在植被生长初期表现为模拟结果没有明显的规律性;通过相干和非相干散射模型的比较分析,证实由散射机制引起的相干性是较小的。结论]文中只分析了随入射角变化,相干和非相干散射模型的差异,在以后的研究中,需要进一步分析该差异随植被和土壤参数的变化情况。

Comparisons between Microwave Coherent and Incoherent Scattering Models in Corn Field

Object] The aim was to compare and analyze microwave coherent and incoherent scattering models in a corn field.Method] In the research,based on a coherent scattering model(Stile),we proposed a coherent scattering model exclusive for corn,in which,physical optics(PO) and infinite-length dielectric cylinder were used to calculate single-scattering matrices of corn leaves and stalks.In addition,coherent components produced from interaction among the scattering mechanisms were also considered and this coherent model was compared with the Michigan Microwave Canopy Scattering(MIMICS).The measured data in a corn filed in Gongzhuling in Jilin Province were used as the input parameters of the coherent and incoherent models.We simulated backscattering coefficients of VV and HH polarization at L and C bands and made a comparison between the simulation results.Result] The simulation results at L-band were poor,which indicated that we could not find regularity at early growth stage of vegetation.In addition,comparisons between coherent and incoherent scattering models proved that the coherence triggered by the scattering mechanism was small.Conclusion] In the research,we only analyze differences between coherent and incoherent scattering models with change of incident angle,and further analysis on the differences with change of vegetation and soil needed to be made in future.