多层积雪相干散射模型与SAR参数反演

Focus on the coherent scattering transmission mechanisms problem of active microwave signal in the SAR image of multi-layer snow under vegetation cover, we will establish the multi-layer snow coherent scattering model applies to the active microwave observation under vegetation coverage condition, based on Intensive Media Radiative Transfer equation, considering the multi-layer features of the snow layer and the coherent scattering between snow particles. By means of the analytic solution and numerical simulation two-pronged approach, the model will be calculated the extinction coefficient, scattering coefficient and phase matrix of the snow layer at the different snow parameters conditions, joined boundaries condition of the air-snow layer and the snow-surface layer, and vegetation cover conditions. We will develop the snow parameter retrieval models and methods through the analysis of response relationship of vegetation cover, snow layer physical parameters to the back scattering coefficient, and will validate the model and test algorithms by carrying out collaborative observation experiment, obtaining spaceborne SAR, scattering characteristics measurements and in-suit field samples of ground snow cover and vegetation parameter measurement,to validate scattering model and retrieval algorithms. The project will solve the shortage problem of analytical solution accuracy for the radiative transfer equation in the past, the inversion problem of snow parameters considering the vegetation cover and providing theoretical and technical support for the applications of multi-source polarization SAR.

针对主动微波信号在植被覆盖区多层积雪传输中的相干散射机制问题，基于密集介质辐射传输理论，考虑雪层的多层特性和雪粒子间的相干散射，从解析求解和数值模拟两方面入手，得到不同积雪参数条件下雪层的消光系数、散射系数和相矩阵，并加入空气－雪层、雪层－地表边界和植被覆盖条件，建立适用于主动微波后向观测的植被覆盖区多层积雪相干散射模型。 通过分析植被覆盖、雪密度、雪厚度等物理参数与后向散射系数的响应关系，建立考虑植被影响的积雪参数反演模型与方法。开展积雪区野外观测实验，获取星载SAR数据、散射特性测量数据和地面同步观测数据，验证发展的积雪模型和积雪反演方法的可靠性。 本项目将解决过去辐射传输方程解析解精度不足问题，植被覆盖条件下积雪参数反演问题，为多源极化SAR数据的应用提供理论和技术支持。

项目开展主动微波信号在多层积雪传输中的相干散射机制研究，解决如何精确地描述积雪层内的近场多次相干散射参数，如何准确刻画分层导致的层间多次散射对雷达后向散射信号的影响，以及植被模型和多层积雪模型综合等问题，研制主动微波多层积雪相干散射模型，分析多层积雪相干散射特征，发展植被覆盖区积雪参数反演模型与方法，并进行积雪覆盖区野外观测实验与验证。.项目基于密集介质的辐射传输方程，从解析求解和数值模拟两方面入手，得到不同积雪参数条件下雪层的消光系数、散射系数和相矩阵，并加入空气－雪层和雪层－地表边界和植被覆盖条件，建立了单、多层积雪QCA/InSAR积雪相干散射模型；基于理论模型的模拟结果，在分析植被覆盖、雪层物理参数与雷达后向散射系数的响应关系基础上，发展了基于该模型的积雪多参数同时反演的方法，为准确刻画目标分层的层间多次相干散射及多源SAR应用提供理论和技术基础。.开展了积雪区野外观测实验，获取星载SAR数据、散射特性测量数据和地面同步观测数据，积累了一批不同尺度的常年积雪区和季节性积雪区采样数据。通过项目实施提高了雷达回波与植被、积雪参数间定量关系的认知水平，对促进SAR数据在积雪监测，积雪水文和气候变化研究方面的应用能力具有重要意义。