NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Geometric basis for the far red shiftAn alternative explanation is offered for the redshift (an abrupt change in the ratio of scattering to absorption in the radiance spectra of heading canopies of such crops as wheat and grain sorghum). The shift occurs abruptly at wavelengths near the red-infrared boundary towards the longer wavelengths. The new explanation, following that of Collins (1978) and Schutt et al. (1984), is based on one particular architectural change that occurs in any heading plant canopy. Specifically, the newly extended heads alter the interaction between light and the established foliage. The heads reduce the amount of sunlight striking the topmost leaves which are generally comparatively good specular reflectors. The heads also reduce the ability to observe the specularly reflecting leaves. The reduction in the amplitude of the radiance (due to decreased specularly reflected light) at heading appears to be a shift in the wavelength of the red edge. It is proposed that vertical (amplitude) shifts - due to changes in the amount of specularly reflected light as a function of heading - have been misinterpreted as horizontal (wavelength) shifts due in part to the characteristic shape of the radiance curve at the red edge.
Document ID
19860048882
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Vanderbilt, V. C.
(Purdue Univ. West Lafayette, IN, United States)
Grant, L.
(Purdue University West Lafayette, IN, United States)
Date Acquired
August 12, 2013
Publication Date
January 1, 1985
Subject Category
Earth Resources And Remote Sensing
Accession Number
86A33620
Funding Number(s)
CONTRACT_GRANT: NAG5-269
Distribution Limits
Public
Copyright
Other

Available Downloads

There are no available downloads for this record.
No Preview Available