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Simulated directional radiances of vegetation from satellite platformsA computer modeling and simulation investigated the effects of off-nadir viewing, canopy geometry and density, solar zenith angle, and atmospheric conditions on the radiance of several vegetated targets. Effects on the normalized difference (ND) index were also investigated, and two wavelengths of 0.68 and 0.80 micron were simulated at nine sensor zenith angles, five sensor azimuths, and nine solar zenith angles. Seven canopies of low, medium, and high densities were observed, and bidirectional reflectance functions of other canopies were discussed. A modified Turner's (1974) atmospheric radiative transfer model was used for 2300 simulation runs. Off-nadir viewing effects were more pronounced in the red than the infrared, and the variability was found to be a function of canopy geometry. The ND index eliminated much of the variability seen in the individual bands, while the overall variability decreased with increasing biomass, and increased with increasing solar zenith angles.
Document ID
19810061031
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Kirchner, J. A.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Schnetzler, C. C.
(NASA Goddard Space Flight Center Earth Resources Branch, Greenbelt, MD, United States)
Smith, J. A.
(Colorado State University Fort Collins, CO, United States)
Date Acquired
August 11, 2013
Publication Date
September 1, 1981
Publication Information
Publication: International Journal of Remote Sensing
Volume: 2
Subject Category
Earth Resources And Remote Sensing
Accession Number
81A45435
Distribution Limits
Public
Copyright
Other

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