期刊名称：ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences
印刷版ISSN：2194-9042
电子版ISSN：2194-9050
出版年度：2007
卷号：XXXVI-7/C50
出版社：Copernicus Publications
摘要：Leaf area index (LAI) is a key parameter governing atmosphere-vegetation interactions. The Global Climate Observing System (GCOS) has identified LAI as an essential climate variable to be mapped globally at 250m resolution at accuracies on the order of +/-0.5 unit. GCOS also identifies satellite remote sensing as the only current technology that can provide required coverage. However, the GCOS implementation document suggests that passive optical sensors have problems with LAI retrieval due to a) noise in understory variability and b) with saturation in the signal from passive optical sensors at LAI levels commonly found in forest biomes. These conclusions have been based predominantly on empirical and model based studies that attempt to relate LAI to spectral measurements in visible and near infrared wavelengths. Visible wavelengths are also problematic for operational LAI retrieval due to inherent uncertainties in atmospheric correction over low reflectance (e.g. dense forest) targets
