INTERACTION OF PHOTONS IN A CANOPY OF FINITE-DIMENSIONAL LEAVES

The physics of neutral particle interaction for photons traveling in media consisting of finite-dimensional scattering centers that cross-shade mutually is investigated. A leaf canopy is a typical example of such media. The leaf canopy is idealized example of such media. The leaf canopy is idealized as a binary medium consisting of gaps (voids) and regions with phytoelements (turbid phytomedium). Gaps through which photons travel unimpededly are assumed to be randomly distributed. The mathematical approach for characterizing the structure of the host medium is considered in detail. In this approach, the leaf canopy is represented by a combination of all possible open oriented spheres. With rigorous definitions and notations, dependence of the extinction coefficient on the phase-space coordinates of the previous interaction center is shown to be a logical consequence. Specifically, the extinction coefficient at any phase-space location in a leaf canopy is the product of the extinction coefficient in the turbid phytomedium and the probability of absence gaps at that location. Using a similar approach, an expression for the differential scattering coefficient is derived. Numerical results are presented to illustrate the influence of canopy parameters and direction of photon travel on the extinction coefficient.