1 November 1997 Effect of three-dimensional canopy architecture on thermal infrared exitance
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Abstract
We present a theoretical study of the effects of threedimensional canopy structure on directional thermal infrared exitance. A physics-based model employing steady-state energy budget formulations is used to compute scene element temperatures. Two approaches are then used to combine soil and vegetation contributions to the composite scene response. One method uses a plane-parallel abstraction of canopy architecture to estimate canopy view factors for weighting of soil and vegetation emission terms. The second approach employs computer graphics and rendering techniques to estimate 3-D canopy view factors and scene shadows. Both approaches are applied to a test agricultural scene and compared with available measurements. The models correctly estimate hemispherically averaged thermal infrared exitance to within experimental error with root-mean-square errors of 15.3 W m-2 for the 1-D model and 12.5 W m-2 for the 3-D model. However, the 1-D model systematically underestimates exitance at high sun angles. Explicit modeling of canopy 3-D row structure indicates potential directional anisotropy in brightness temperature of up to 14°C.
James Alan Smith, James Alan Smith, Jerrell R. Ballard, Jerrell R. Ballard, Jeffrey A. Pedelty, Jeffrey A. Pedelty, } "Effect of three-dimensional canopy architecture on thermal infrared exitance," Optical Engineering 36(11), (1 November 1997). https://doi.org/10.1117/1.601527 . Submission:
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