Knowledge Bank

Measurements of the solar intensity by the University of Denver scanning spectrometer were made during a balloon ascent to 40 km on 3 December 1974. Spectral resolution was 0.01 $\mu$m. A filter radiometer measured the sun continuously in the 11 $\mu m$ window. Combining the radiometer output with a spectral scan of a hot laboratory source and published solar spectral radiances provides a 100% level, which is tested against the spectrometer data in the wings of the band at the higher altitudes. Spectral transmittance versus pressure for the solar zenith angle during the ascent will be used as a standard for the general computation of atmospheric transmittances to be used with satellite data for indirect sounding of atmospheric temperature.