Scaling-up and model inversion methods with narrowband optical indices forchlorophyll content estimation in closed forest canopies with hyperspectral data

Citation
Pj. Zarco-tejada et al., Scaling-up and model inversion methods with narrowband optical indices forchlorophyll content estimation in closed forest canopies with hyperspectral data, IEEE GEOSCI, 39(7), 2001, pp. 1491-1507
Citations number
58
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Eletrical & Eletronics Engineeing
Journal title
IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING
ISSN journal
0196-2892 → ACNP
Volume
39
Issue
7
Year of publication
2001
Pages
1491 - 1507
Database
ISI
SICI code
0196-2892(200107)39:7<1491:SAMIMW>2.0.ZU;2-6
Abstract
Radiative transfer theory and modeling assumptions were applied at laborato ry and field scales in order to study the link between leaf reflectance and transmittance and canopy hyperspectral data for chlorophyll content estima tion. This study was focused on 12 sites of Acer saccharum M. (sugar maple) in the Algoma Region, Canada, where field measurements, laboratory-simulat ion experiments, and hyperspectral compact airborne spectrographic imager ( CASI) imagery of 72 channels in the visible and near-infrared region and up to I-m spatial resolution data were acquired in the 1997, 1998, and 1999 c ampaigns. A different set of 14 sites of the same species were used in 2000 for validation of methodologies. Infinite reflectance and canopy reflectan ce models were used to link leaf to canopy levels through radiative transfe r simulation. The closed and dense (LAI > 4) forest canopies of Acer saccha rum M. used for this study, and the high spatial resolution reflectance dat a targeting crowns, allowed the use of optically thick simulation formulae and turbid-medium SAILH and MCRM canopy reflectance models for chlorophyll content estimation by scaling-up and by numerical model inversion approache s through coupling to the PROSPECT leaf radiative transfer model. Study of the merit function in the numerical inversion showed that red edge optical indices used in the minimizing function such as R-750/R-710 perform better than when all single spectral reflectance channels from hyperspectral airbo rne CASI data are used, and in addition, the effect of shadows and LAI vari ation are minimized. Estimates of leaf pigment by hyperspectral remote sens ing of closed forest canopies were shown to be feasible with root mean squa re errors (RAISE's) ranging from 3 to 5.5 mug/cm(2). Pigment estimation by model inversion as described in this paper using these red edge indices can in principle be readily transferred to the MERIS sensor using the R-750/R- 705 optical index.