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叶面积指数(LAI)的地面验证是LAI反演算法研究及LAI产品验证的重要部分。近年来,为了验证遥感参数产品以及对大气、地表的系统性研究,国际上在全球主要大洲开展了多个针对主要植被类型的大型观测项目,逐渐形成了较完善的地面采样框架与全球尺度不同植被类型的地面验证数据集。国内外已开展的大型观测项目采用的采样框架对以后观测试验中LAI的地面验证框架的制定与研究具有重要的借鉴意义,同时,已观测到的全球LAI地面验证数据集是开展全球LAI算法及产品验证的基础数据集,因此,有必要对目前全球LAI地面验证方法及验证数据情况做个综述。首先综述全球主要LAI地面观测项目及其所采用的地面验证框架。在此基础上,分析比较各大观测项目中所采用的地面测量方法、采样方法及像元真值估算方法。最后,指出全球LAI产品地面验证中存在的不足,并对尚需进一步研究的方向进行展望。
LAI ground validation is an important part of LAI inversion algorithm research and LAI product verification. In recent years, in order to verify the remote sensing parameters of products and the systematic study of the atmosphere and the surface, a large number of large-scale observational projects on major vegetation types have been carried out on major continents around the world. A relatively complete ground-based sampling framework and a global scale Vegetation type of ground validation data set. The sampling framework adopted by large-scale observational projects both at home and abroad has important reference for the formulation and research of LAI ground validation framework in future observational experiments. At the same time, the observed global LAI ground validation dataset is used to carry out the global LAI algorithm and Therefore, it is necessary to summarize the current global LAI ground verification methods and verification data. First, an overview of the major LAI ground-based observational projects in the world and the ground-based validation framework used will be provided. On this basis, the ground measurement methods, sampling methods and pixel true value estimation methods used in major observational projects are analyzed and compared. Finally, it points out the shortcomings in the ground-based verification of LAI products in the world and looks forward to further research.