Determination of extraterrestrial solar spectral irradiance from a research aircraft.

Results are presented of an experiment to determine extraterrestrial solar spectral irradiance at the earth's mean solar distance within the 300-2500 nm wavelength region. Spectroradiometric measurements were performed during eleven research flights on board a NASA CV-990 aircraft at altitudes between 11.6 km and 12.5 km. Precision of the measurements was better than +/-1%. Absolute accuracy of the resultant extraterrestrial solar spectral irradiance is approximately +/-3% over most of the measurement range. A listing of results is presented at intervals varying from 0.1 nm throughout most of the uv-visible Fraunhofer region to 5 nm in the continuum region of the ir. Additionally, a listing of solar spectral irradiance, smoothed over the detailed Fraunhofer structure, is presented for engineering use.