Abstract. The total column ozone (TCO3) measurements by the Dobson
spectrophotometer (serial no. 84) have been carried out at Belsk station
(51∘50′ N, 20∘47′ E), Poland, since 23 March 1963. In total, ∼115 000 intraday manual observations were made by 31 December 2019. These observations were performed for different combinations of double wavelength pairs in the ultraviolet range and observation types, i.e., direct sun (DS), zenith blue (ZB), and zenith cloudy (ZC) depending on weather conditions. The long-term stability of the instrument was supported by frequent (almost every 4 years) intercomparisons with the world standard spectrophotometer.
Trend analyses, based on the monthly and yearly averaged TCO3, can be
carried out without any additional corrections to the intraday values. To
adjust these data to the Brewer spectrophotometer observations, which were
also performed at Belsk, a procedure is proposed to account for less
accurate Dobson observations under low solar elevation, presence of clouds,
and the temperature dependence of ozone absorption. The adjusted time series
shows that the Brewer–Dobson monthly averaged differences are in the range of about ±0.5 %. The intraday TCO3 database, divided into
three periods (1963–1979, 1980–1999, and 2000–2019), is freely available
at https://doi.org/10.1594/PANGAEA.919378 (Rajewska-Więch et al., 2020).