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Relationships between vegetation indices, radiation absorption, and net photosynthesis evaluated by a sensitivity analysisA two-stream approximation to the radiative-transfer equation is used to calculate the vegetation indices (simple ratio and normalized difference), the fraction of incident photosynthetically active radiation (PAR) absorbed by the canopy, and the daily mean canopy net photosynthesis under clear-sky conditions. The model calculations are tested against field observations over wheat, cotton, corn, and soybean. The relationships between the vegetation indices and radiation absorption or net photosynthesis are generally found to be curvilinear, and changes in the soil reflectance affected these relationships. The curvilinearity of the relationship between normalized differences and PAR absorption decreases as the magnitude of soil reflectance increases. The vegetation indices might provide the fractional radiation absorption with some a priori knowledge about soil reflectance. The relationship between the vegetation indices and net photosynthesis must be distinguished for C3 and C4 crops. Effects of spatial heterogeneity are discussed.
Document ID
19870059267
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Choudhury, Bhaskar J.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Date Acquired
August 13, 2013
Publication Date
July 1, 1987
Publication Information
Publication: Remote Sensing of Environment
Volume: 22
ISSN: 0034-4257
Subject Category
Earth Resources And Remote Sensing
Accession Number
87A46541
Distribution Limits
Public
Copyright
Other

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