The results of 900 spectral measurements taken at 35 km altitude in the 2800-Å to 3600-Å wavelength region with 100-Å resolution are given and compared with previous work. The instrument was stepped in elevation from 45° below to 70° above the horizon and was rotated in azimuth. The sun varied in elevation angle from zero to 60°. The signal varied by two orders of magnitude with instrument elevation angle, the minimum occurring at +70° and the maximum at -15° (1.5 × 10-2 W/cm2 sr µ at 3600 Å and the sun at 60° elevation). The radiance level below 3300 Å dropped more rapidly with decreasing wavelength for down-looking than for up-looking instrument elevation angles. The radiance varied by a factor of two with azimuth angle, but with a different trend for downward-looking than for upward-looking instrument elevation angles.
M. Dorian and F. Harshbarger, "Measurement of the Atmospheric Spectral Radiance at 35 km in the Near Ultraviolet," Appl. Opt. 6, 1487-1491 (1967)