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：2010
卷号：XXXVIII - Part 8
页码：609-614
出版社：Copernicus Publications
摘要：The Moderate Resolution Imaging Spectroradiometer (MODIS) is the primary NASA Earth Observing System instrument monitoring the seasonality of global terrestrial vegetation. MODIS products, such as the MODIS Vegetation Index (VI), Normali zed Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI), and Leaf Area Index (LAI), are commonly used for evaluating the ecological variables. In this study, we examined the LAI – VI relationship based on in situ data. Two VIs as NDVI and EVI were measured from a hemispherical spectroradiometer (HSSR) at the study site, Takayama in Central Japan. LAI data were observed based on phenology shoot and litter trap approaches from 2005-2006. To compare in situ NDVI and EVI to in situ LAI, we investigated two patterns: a single r elationship using all of the data and a double relationship of two periods (gr owing to s aturation and saturation to leaf-fall). These equations from the regression function were used to apply to MODIS NDVI and EVI 8 day composite data for LAI estimation. MODSI EVI presents better results than does MODSI NDVI and is a fairly good match to in situ LAI, with r 2 = 0.89 and 0.94, respectively. Furthermore, NDVI MODIS yielded seasonally earlier LAI values than did in situ LAI estimates, as it included the forest floor. The double relationship improved the accuracy of LAI estimates over that of the single relationship. The overestimation error of single-relationship NDVI MODIS was reduced, and forest floor reflectance in the early growing season was decr eased, thus fitting better to in situ LAI values. The fluctuation of both NDVI MODIS and EVI MODIS winter LAI estimates derived from the single relationship was considerably removed, and both were close to reflecting the actual leafless condition of winter. Moreover, MODIS LAI 8 day composite images were applied to compare among the results for validation. It was showed that MODIS LAI provided overestimated LAI than usual. However, validation with further comparisons is still needed
关键词：Leaf area index; Normalized different vegetation index; Enhanced vegetation index; Deciduous broadleaf forest; in ; situ measurement; regression relationship
