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Radiative transfer in shrub savanna sites in Niger : preliminary results from HAPEX-Sahel . 1 . Modelling surface reflectance using a geometric-optical approach
| Content Provider | Semantic Scholar |
|---|---|
| Author | Janet Franklin Duncan, Jeff Alfredo Leeuwen |
| Abstract | To use optical remote sensing to monitor land surface-climate interactions over large areas, algorithms must be developed to relate multispectral measurements to key variables controlling the exchange of matter (water, carbon dioxide) and energy between the land surface and the atmosphere. The proportion of the ground covered by vegetation and the interception of photosynthetically active radiation (PAR) by vegetation are examples of two variables related to evapotranspiration and primary production, respectively. An areal-proportion model of the multispectral reflectance of shrub savanna, composed of scattered shrubs with a grass, forb or soil understory, predicted the reflectance of two 0.5 km 2 sites as the area-weighted average of the shrub and understory or 'background' reflectances. Although the shaded crown and shaded background have darker reflectances, ignoring them in the area-weighted model is not serious when shrub cover is low and solar zenith angle is small. A submodel predicted the reflectance of the shrub crown as a function of the foliage reflectance and amount of plant material within the crown, and the background reflectance scattered or transmitted through canopy gaps (referred to as a soil-plant 'spectral interaction' term). One may be able to combine these two models to estimate both the fraction of vegetation cover and interception of PAR by green vegetation in a shrub savanna. * Corresponding author. 0168-1923/94/$07.00 :Z'I_1994 Elsevier Science B.V. All rights reserved SSDI 0168-1923(93)02115-M 224 J. Franklin et al./Agricultural and Forest Meteorology 69 (1994) 223-245 |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19960016588.pdf |
| Language | English |
| Access Restriction | Open |
| Subject Keyword | Carbon Dioxide Crown group Franklin Electronic Publishers Interaction Meteorology Motorola Canopy Multispectral image Papio Radiation Shading Sixty Nine Social Security Death Index algorithm disease transmission |
| Content Type | Text |
| Resource Type | Article |
