Airborne measurements of optical atmospheric properties, summary and review, 2

This report summarizes a 3-year period of collecting optical atmospheric data both at night and during the day chiefly with airborne instruments. Four field expeditions were made between September 1972 and June 1975 in various locations in the United States and Europe, primarily during the winter and summer. Measurements were made in five spectral regions, as follows: three narrow band optical filters with mean wavelengths of 478, 664, and 765 nanometers, and two broad band sensitivities, one representing the S-20 multiplier phototube incorporating an ultraviolet rejection filter with a mean wavelength of 532 nanometers, the other representing the photopic response with a mean wavelength of 557 nanometers. Optical measurements included total scattering coefficient and sky and terrain radiance. These data were used to calculate natural irradiance on a horizontal plane surface, directional reflectance of terrain, atmospheric beam transmittance, path radiance, and directional path reflectance. The methods of data collection and data processing are reviewed, the resultant data bank described, and recommendations for further study and interpretation of the data are proposed.