MAX-DOAS NO2 profile retrieval over Minsk: 3 years of observation

For NO₂ monitoring by MAX-DOAS method, the automated instrument MARS-B based on the spectrograph ORIEL MS257 with a Peltier-cooled CCD-array detector Andor Technology DV-420 OE (number of active pixels is 1024×256, working temperature is -40 ºC) has been employed. The MARS-B instrument records the spectra of scattered sunlight in the range of elevation angles 0º – 90º within vertical angle aperture of 1.3º in spectral range 340-400 nm with FWHM = 0.32 nm and is operating without mechanical shutter. Radiation input system is working without optical fiber and spectrograph unit has open-air design, spectrograph unit is temperature-stabilized at level 40 ± 0.5 ºC. The MARS-B instrument successfully took part in MAD-CAT (2013) and CINDI-2 (2016) international inter-comparison campaigns.

Since 2017 MARS-B instrument is performing spectra registering over Minsk (National Ozone Monitoring Research and Education Centre, Minsk, Belarus) using multi-axis geometry of observations during daytime and zenith geometry in twilights. More than 4.5 millions of day-time spectra aiming to retrieve differential slant columns of ozone, nitrogen dioxide and oxygen dimer have been processed by DOAS method. Total nitrogen dioxide columns have been retrieved by PriAM algorithm which is based on optimal estimation method.

Continuous 3-year MAX-DOAS measurements (nitrogen dioxide vertical column, near-surface nitrogen dioxide concentrations, aerosol optical depth) over Minsk in period of 2017 - 2019 will be presented, compared with data of impact gas analyzers and satellite data, analyzed and discussed. Also, zenith twilights measurements will be processed aiming to retrieve stratospheric nitrogen dioxide and ozone columns for comparison with different parameters of solar activity.