This article examines the seasonal and interannual spatial variability of the equilibrium partial pressure of carbon dioxide pCO2 in the surface water layer and the carbon dioxide flux FCO2 at the atmosphere-sea interface for the Black Sea based on biogeochemical reanalysis data. In situ measurements for 2015–2024 were used to validate the reanalysis data and compare the seasonal variations of pCO2 and FCO2. Additionally, pCO2 from reanalysis data in the surface layer of the atmosphere was compared with instrumental measurements. Seasonal cycles of the polygon-averaged FCO2 flux and the equilibrium partial pressure in the near-surface layer of the sea, based on instrumental observations and biogeochemical reanalysis data, coincide within 95% confidence intervals, with the exception of the summer season for pCO2. Statistically significant regression relationships (p<0.001) were established between the parameters under consideration. As a result, the reanalysis data provided new insights into the seasonal variability of pCO2 and FCO2 throughout the sea area. This is particularly relevant when observational data are lacking for the winter and spring periods and the expedition area is limited. Seasonal variability of pCO2 and FCO2 is primarily influenced by water temperature and the difference in partial CO2 pressure between the sea and the atmosphere. The distribution of pCO2 and FCO2 on the shelf and in the coastal zone of the sea demonstrates the significant influence of upwellings near Crimea and river plumes on the seasonal dynamics of FCO2.