Application of Kitt Peak Solar Flux Atlas for studying air pollution in Tokyo area

The air pollution in Tokyo area due to anthropogenic NO₂ has been observed. The method of optical absorption spectrometry based on the Noxon method measures the whole spectral region of NO₂ absorption. Instead of using the Langley method (long method) to retrieve extraterrestrial solar radiation, the solar radiation just above the Earth atmosphere is substituted by the Kitt Peak Solar Flux Atlas. The large Fraunhofer features (20-40%) are eliminated by wavelength correction, resolution matching and ratioing of observed spectra to the reference. The NO₂ absorption structure is clearly observed. With this technique, the study of tropospheric air pollution in the urban area has been conducted for a high-degree of air pollution. The NO₂ vertical column density has turned out to change in accordance with the ground mixing ratio. The observation shows that a high degree of air pollution occurs in Kanto Plain area not only in the early winter but also in autumn