Corrections to the standard retrieval of total ozone column with a Dobson spectrophotometer operated at Belsk, Poland, since 1963

Monitoring of total ozone column (TOC) were carried out at Belsk (51°50'N, 20°47'E), Poland, using a Dobson spectrophotometer (DOB) for the period 1963-2024. Various combinations of DOB settings are applied in the TOC monitoring, including double wavelength pairs (AD or CD) and observation types: direct sun (DS), zenith blue (ZB), or zenith cloudy (ZC). Current DOB TOC retrieval uses the Bass-Paur (BP) ozone absorption cross-section (OACS), which is fixed at a temperature of - 46.3 °C. Recently, the Absorption Cross Sections of Ozone committee recommended changing from the BP OACS to the temperature-dependent Serdyuchenko-Gorshelev (SG) OACS. This paper incorporates the SG OACS into the DS TOC standard calculation, which is based on the Beer-Lambert law, and into the non-DS TOC retrieval, using an empirical approach to adjust TOC values obtained from the attenuation of zenith solar irradiance to the most reliable DS-AD TOC values. An empirical correction function is also proposed to reduce the effect of stray light (SL) on DOB TOC values. Using the SG OACS and SL correction reduces the winter-summer bias relative to the Brewer spectrophotometer to ± 0.5% for DS measurements. The difference between DOB and reanalysis/satellite TOC values decreases by approximately 2% in winter.