What causes changes in Black Sea water levels when tides are weak?

In the Black Sea, where tides are virtually nonexistent, water level variations are primarily driven by seiches. These are changes in water level caused by rapid fluctuations in atmospheric pressure.1

Additionally, the overall water balance of the sea—which influences annual water levels—is determined by a combination of factors, including precipitation, inflow from the continental mass and the Sea of Azov, surface evaporation, and water exit through the Bosporus.1