O3 and NO2 vertical columns using SAOZ UV-Visible spectrometer

This chapter presents an overview of ground-based SAOZ spectrometer for measurements of O3 and NO2 total vertical columns. Due to instrument conception (zenith measurement in the Visible), the SAOZ is the only instrument that could measure continuously and at all latitudes up to the polar circle in winter. It can be operated in bad weather conditions (cloudy, rainy or snowing) and it has the advantage of spectral self-calibration and completely automatic mode. Differential Optical Absorption Spectroscopy technique is used allowing a self-calibration of different atmospheric constituents on the respective absorption cross-section.