Analysis of space distribution of scattered light by monte carlo method in consideration of atmospheric particles

Study on the brightness of airport light systems, especially on how much light is scattered by the atmospheric particles, is important under low visibilities. In this paper, a simulation was programmed to analyze space distribution of scattered light by Monte Carlo method, based on scattering by a single particle calculated through Mie Theory. There is no limitation to the position of particles. Effects of visibility, of particle size distribution, and of light wavelength can be taken into consideration. With this program, we studied the variation of luminance distribution with the change in visibility, position of a pilot looking at the airport and the surroundings when approaching, and so forth. The result shows that the scattering of the airport light may add some influence on the brightness of the airport light in the twilight and at night. The simulation had a slight deviation from the calculation using Koschmieder formula for additional luminance with scattered daylight. Particle size distribution greatly affected airport light scattering, while it had little effect on daylight scattering.