异质性草原植被BRDF模拟及弱敏感参数反演方法研究

该项目针对异质性草原植被BRDF模拟及弱敏感参数反演两个关键理论问题开展研究。一方面, 针对草原多类型植被混杂而形成的异质性特征, 深入剖析经典一维植被辐射传输模型构建机理, 结合蒙特卡罗光线追踪技术模拟异质性草原植被辐射传输特性, 扩展一维植被冠层BRDF模型, 构建适合异质性草原植被的BRDF模型; 另一方面, 对模型自由参数之间的相关性及其先验知识的不确定性进行定量描述的基础上, 基于构建的植被BRDF模型和多时相遥感数据, 以干物质重量等重要但弱敏感的植被生化参数为反演目标, 构建一套有效的植被弱敏感参数反演方法。这些关键理论与方法的突破, 将为异质性草原植被BRDF模拟及弱敏感参数反演提供新的理论与方法支持, 扩展植被辐射传输模型的应用范围，提升遥感参数反演的精度, 对于监测大面积草原植被生长状况,评估草原发生火灾的风险程度等具有重要的现实意义。

This project focuses on the modeling of the bidirectional reflectance distribution function (BRDF) and retrieval of weak sensitive parameters of vegetation in heterogeneous grassland. The BRDF of mixed multi-type (heterogeneous) herbage is to be modeled based on the physical mechanism of the classical radiative transfer models of one-dimensional turbid medium and the Monte Carlo ray-tracing technique. The modeled model is to make sense to extend the use of the physical mechanism based model. The important but weak sensitive parameters of herbage, such as the dry matter content (DMC) is to be retrieved in the project by taking into account the correlation among free parameters of the model as well as the uncertainty of prior information. The modeling of BRDF of the heterogeneous herbage and the retrieval methods allow the improvement of the precision level of retrieval of the weak sensitive parameters, which is not only meaningful to monitor the growth state of herbage but also to evaluate the risk of grassland fire.