Analysis of Space Distribution of Scattered Light by Monte Carlo Method Taking Account of the Atmospheric Particles

Abstract

It is very useful to study brightness of airport light system under low visibility condition to analyze how much light is scattered by the atmospheric particles. In this paper a simulation program was produced to analyze the space distribution of scattered light by a Monte Carlo method, based on the scattering properties of a single particle as calculated by Mie theory. This program does not set a limit to the position of scattering particles, and can take account of not only the influence of visibility but also that of the distribution of particle size and the wavelength of light. By using the program, the variation of luminance distribution with visibility, observation position, etc. was investigated from the viewpoint of a pilot looking at the airport and its surroundings during approach. This result shows that additional luminance due to the scattering of the airport light may have an influence on brightness of airport light in the night and twilight. It also shows that calculated value by means of this simulation technique is not perfectly equal to that of Koschmieder formula for additional luminance by the scattering of daylight. The distribution of particle size has a great influence on the scattering of airport light. On the other side, it does not have a great influence on the scattering of daylight.