Purpose. The purpose of the study consists in describing the parameterization based on the field data, which take into account the relationship between the variability of pCO2 sw and the state of the surface water layer, depending on the sea surface temperature and allowing for geographical location and seasonality at the example of the Black Sea.
Methods and Results. The main seasonal trends of changes in pCO2 related to the variations in sea surface temperature are proposed based on special processing of direct measurement data on pCO2 of the surface layer obtained in the cruises of R/V Professor Vodyanitsky in 2015–2023 and at the stationary observation point of the Black Sea Hydrophysical Subsatellite Polygon (BSHSP), Katsiveli, in 2012–2022. The basic approach consists in describing the variations in pCO2 sw distribution over the sea surface using the linear approximations (trends) for three fixed seasons represented by four months (January – April, May – August and September – December) in each of the grid cells. It is shown that both in the coastal zone and in the open sea, the hysteresis dependences of pCO2 upon the sea surface temperature are manifested: the ratios of partial pressure and temperature during the periods of spring warming and autumn cooling are different. The reason for the observed hysteresis is related to a shift of the pCO2 sw fluctuation phase and a temperature change of about 1.5–2 months.
Conclusions. The dependence of pCO2 upon the sea surface temperature in an autumn-winter period turns out to be close to the dependences typical for the oceanic conditions in mid latitudes of the Northern Hemisphere (the Atlantic and Pacific oceans). This can indicate the universal mechanisms of influence of the sea surface temperature (SST) upon pCO2 sw both for the local conditions in the Black Sea and for the open ocean during a certain seasonal period. Besides, such a similarity of dependences can mean that, most likely, SST directly conditions a value of pCO2 sw, whereas biological activity is not a determining factor. The obtained results can be used for describing and studying the variations of the CO2 sea – air fluxes in the Black Sea.