Ciencias Agrarias >
Instituto de Agricultura Sostenible (IAS) >
(IAS) Comunicaciones congresos >
Open Access item Estimation of Chlorophyll Fluorescence under Natural Illumination from Hyperspectral Data
|Authors:||Zarco-Tejada, Pablo J.|
Miller, J. R.
Mohammed, G. H.
Noland, T. L.
Sampson, P. H.
|Keywords:||Reflectance, Chlorophyll Fluorescence, Red Edge, Radiative Transfer, CASI, Hyperspectral|
|Abstract:||This paper reports a series of laboratory and field measurements of spectral reflectance under artificial and natural light
conditions which demonstrate that effects of natural chlorophyll fluorescence are observable in the reflectance red edge
spectral region. These are results from the progress made to link physiologically-based indicators to optical indices from
hyperspectral remote sensing in the Bioindicators of Forest Sustainability Project. This study is carried out on twelve
sites of Acer saccharum M. in the Algoma Region, Ontario (Canada), where field measurements, laboratory-simulation
experiments, and hyperspectral CASI imagery have been carried out in 1997, 1998, 1999 and 2000 campaigns. Leaf
samples from the study sites have been used for reflectance and transmittance measurements with the Li-Cor Model
1800 integrating sphere apparatus coupled to an Ocean Optics Model ST1000 fibre spectrometer in which the same
leaves are illuminated alternatively with and without fluorescence-exciting radiation. A study of the diurnal change in
leaf reflectance spectra, combined with fluorescence measurements with the PAM-2000 Fluorometer show that the
difference spectra are consistent with observed diurnal changes in steady-state fluorescence. Small canopies of
Acer saccharum M. have been used for laboratory measurements with the CASI hyperspectral sensor, and under natural
light conditions with a fibre spectrometer in diurnal trials, in which the variation of measured reflectance is shown
experimentally to be consistent with a fluorescence signature imposed on the inherent leaf reflectance signature. Such
reflectance changes due to CF are measurable under natural illumination conditions, although airborne experiments with
the CASI hyperspectral sensor produced promising but less convincing results in two diurnal experiments carried out in
1999 and 2000, where small variations of reflectance due to the effect of CF were observed.|
|Description:||Presented at the Second EARSeL Workshop on Imaging Spectroscopy, Enschede (Holland), 11th-13th July 2000.|
|Appears in Collections:||(IAS) Comunicaciones congresos|
Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.