Observations of the ozone and nitrogen dioxide profiles in the TROICA-4 experiment

To investigate the vast area of Russia, a mobile scientific facility based in a railway carriage was developed. It is capable to perform continues measurements being coupled in a passenger train traveling along railroads. It was first equipped with a spectrometer for remote sensing of ozone and nitrogen dioxide in the atmosphere for the transcontinental observations into the chemistry of the atmosphere-4 expedition performed from February 18 to March 5, 1998. A twilight DOAS method, which was applied for retrieval of the nitrogen dioxide profiles basing on spectral measurements at the visible wavelengths (434-451 nm), is described in the paper. Main features of a new algorithm for retrieval of the ozone profile and total content using the differential structure of the UV spectrum (310-335 nm) are presented. The ozone and nitrogen dioxide contents are obtained and shortly validated against available alternative data.