Effects of atmospheric aerosols on scattering reflected visible light from earth resouce features

The purpose of this investigation was to identify the vertical variations in atmospheric light attenuation under ambient conditions and to provide a method through which aerial photographs of earth features might be corrected to yield quantitative information about the actual features. A theoretical equation has been developed based on the Bouguer-Lambert extinction law and basic photographic theory. This provided a relationship between the actual density of the photographic negative of an object (D0), the density (D) of the same object at a given altitude (X), and the coefficient of extinction of light (b). This equation states that where 1D, 1B, and 10 are determined from the measurable Hurter and Driffield characteristic curve of the photographic material. Measurements were made of the initial density produced by the energy reflected from control targets on the ground and the density produced by the energy received at flight altitudes through the use of photography. Measurements of the loss of energy at different altitudes due to light scattering in the vertical were made by an integrating nephelometer. These independent measurements were compared through the theoretical equation developed. The theoretical equation has been found to hold for the altitudes studied (altitudes up to 9000 feet above the ground) within the experimental accuracy of the experiments performed. The overall research effort has provided the following important information. 1. It has provided a method to determine the accumulative bX between the ground and an altitude, X, based on ground density data and aerial ·density data. As a result the average b can be determined. 2. For remote sensing of the environment, it has provided a method through which aerial photographs of earth features can be corrected for the attenuation of light due to an aerosol layer between the ground and the altitude specified, provided the coefficient of extinction of the layer is known.