A canopy model for the study of bidirectional reflectance factors in vegetation stands
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PublisherThe University of Arizona.
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AbstractA radiative transfer model for a homogeneous plane parallel vegetative canopy is developed. A method to decompose and calculate the uncollided, once scattered, and multiply scattered radiation components is also presented based on the turbid medium approach. The new model accounts for the some effects exhibited only by homogenous vegetation canopies. This allows the simulation of the scattering processes within the plant canopy as a function of the traditional canopy architecture parameters such as leaf area index (LAI), leaf reflectance and transmittance, and also the canopy height and leaf size, stem etc... This model integrates two different approaches: the turbid medium approach and an approach that takes into account the finite size of the leaves. Furthermore, a state of the art leaf radiation transfer model (PROSPECT) is incorporated into the new model that provides leaf scattering properties as inputs (transmittance and reflectance vs. wavelength). Based on the proposed canopy model, a computer code in MATLAB was formulated using the discrete ordinates numerical method. This was used to calculate the bi-directional reflectance factor for a given geometry and a viewing angle from a plant canopy. The code for the new model is modular and very simple to use. The new model has been validated against other radiative transfer models, and compared with measured data. The results obtained using the model are in good agreement with the measured data.
Degree ProgramGraduate College
Agricultural and Biosystems Engineering