MEASUREMENT OF ATMOSPHERIC NO2 COLUMN DENSITY WITH KITT-PEAK-SOLAR-FLUX-ATLAS AS A REFERENCE

The vertical column abundance of NO2 is measured using direct sunlight . The solar spectra in the wavelength region of 430-450 nm observed fr om the earth's surface are ratioed with a reference spectrum taken fro m the Kitt Peak Solar Flux Atlas. The large Fraunhofer features (20-40 %) are eliminated by wavelength correction, resolution matching and ra tioing of observed spectra to the reference. The retrieved values of t he NO2 vertical column density are in a range of (2-15)x10(16) molecul es/cm(2) with an accuracy of better than 3%. This result demonstrates the usefulness of the Kitt Peak Atlas in the study of tropospheric NO2 concentration, giving a standard extraterrestrial solar spectrum for the case in which the Langley method is not readily applicable.