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%0 Journal Article
%4 sid.inpe.br/iris@1912/2005/07.20.04.27
%2 sid.inpe.br/iris@1912/2005/07.20.04.27.26
%@issn 2324-9250
%F 7044
%T Soil and litter reflectance contrast effects on vegetation indices and their relationship to FAPAR
%D 1994
%9 journal article
%A Epiphanio, José Carlos Neves,
%A Huete, A. R,
%B EOS Transactions
%V 75
%N 44
%P 206
%K Vegetation indices (VIs).
%X Vegetation indices (VIs)derived from remote sensing data are related to important vegetation parameters, e.g. fAPAR and LAI. These parameters are regular inputs to models of primary productivity. Generally, VIs use relationships between near infrared (NIR)and red reflectances and may utilize the blue band for atmospheric correction. Soil brightness influences on canopy reflectance and VIs have been well shown. Soil color effects as well as canopy backgrounds with litter present, however, have been less well studied. These backgrounds not only affect brightness, but also significantly alter the contrast ratio of NIR and red reflectances. The effects of background NIR/red reflectance contrast due to presence of litter and soil on different VI's were studied using the Myneni canopy radiative transfer model. Several ground cover percentages and two clump LAI's were simulated. The background NIR/red reflectance ratio was varied from 0.9 to 1.5, and the red reflectance was allowed to vary from 0.1 to 0.35, thus covering a large range of background reflectances. It is shown that the NIR/red contrast of backgrounds affect the VIs, and that VIs which reduce background brightness effects also reduce background NIR/red contrast effects, mainly for low vegetation amounts. fAPAR was computed and the effects of background NIR/red reflectance ratio on the relationships between VIs and fAPAR are discussed.
%@language en
%3 INPE 6566.pdf


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