Monte Carlo solutions of the radiative transfer equation for scattering systems.

摘要

The radiative transfer equation (RTE) is solved in this dissertation for a variety of simulated scattering systems. Realistic conditions such as the stratification of a system into layers of different scattering properties, the presence of a dielectric interface that may be either smooth or rough, and the presence of a reflecting bottom boundary are included in the simulations. Solutions to the RTE are obtained numerically using two computer programs that employ state-of-the-art Monte Carlo techniques. One of the programs includes polarization effects, and calculates a sixteen element effective scattering matrix that represents the system of interest. The other program neglects polarization effects and calculates the depth-resolved radiance distribution of the system of interest. The first section of this dissertation introduces and explains briefly radiative transfer theory, the vector nature of electromagnetic radiation and how radiative transfer theory must be modified in order to account for it. The second section introduces and discusses Monte Carlo methods for solving the RTE, including several innovative techniques developed by our research group. The third section describes techniques used to simulate scattering systems. The remainder of the dissertation presents a discussion of data calculated for several different scattering systems. Data calculated including polarization effects are presented for single- and double-layer systems, the latter including first a smooth and then a roughened interface. Comparisons are made with well-known tabulated data for the single-layer calculations. The effect of the interface is demonstrated by comparing a single-layer system with a two-layer system that is identical except for the presence of the interface. The depth-resolved radiance distribution, not including polarization effects, is presented in the fifth chapter. Single-scatter results are compared with those obtained when all orders of scattering are included. Data calculated for several atmosphere-ocean systems, in which the atmosphere remains unchanged but the ocean scattering function is varied, are presented. The results of all calculations are discussed in the context of their applicability to the field of remote sensing.