Parameterization of Thermal Structure of the Black Sea Active Layer at the Gelendzhik Study Site During Warm Period

Using the long-term studies of the Black Sea thermal structure at the Gelendzhik study site, a parameterization of temperature profiles in the active layer was proposed for the warm period (May-November), based on ten-days averaging. It included variability of the upper mixed layer, its temperature and thickness. The 10-days grouping was performed for all studied years (2010–2023) simultaneously, with only day and month being taken into account, to remove synoptic variability and concentrate on general seasonal dynamics. The averaged temperature profiles were transformed into a dimensionless form and described as a universal power function of dimensionless depth. With a reverse transition back to dimensional variables, it was possible to reproduce an annual-average temperature profile in the seasonal thermocline for any particulate day from May to November. Assuming the temperature in the upper mixed layer being the same as at the uppermost part of the thermocline, a thermal structure of the entire active layer therefore could be reconstructed. Calculation examples for different decades are provided, along with comparison of real temperature profiles with the tendays averaged and the formula-based.