Features of the processes of convection and water intrusion at the boundary of the hydrogen sulfide contamination layer in the Black Sea in the climatic period 1991—2020

The comparison of modern hydrophysical conditions in the Black Sea with previously analyzed period 1903—1982 was carried out based on materials recently created (1991—2020) climate array average monthly thermohaline characteristics waters. dynamic processes upper 150-meter layer (halocline) evaluated analysis climatic vertical distribution depth maximum water salinity gradient, which is interpreted as boundary hydrogen sulfide Sea. state and seasonal fluctuations this characteristic during maps by their averaging. According to data(1991—2020), open part sea, a more intense intrusion these waters up horizon 40 m found, well single cases natural release from surface. There clearly pronounced semi-annual cyclicity temporal variability; however, period, shift for whole season: 1903—1982, convection (the downwelling waters) occurred autumn-winter, (upwelling) — spring-summer; 1991—2020 according same data, occurs winter-spring, summer-autumn, occurrence winter-spring minimum summer-autumn intrusion. axes northern southern convergence zones laying near corresponding coasts axis zone central divergence close areas its middle part. By axes, differences between were 21.5 17.5 m, respectively; zone, it 7.5 m.