Role of physical processes controlling oxycline and suboxic layer structures in the Black Sea

Oguz, T
[1] A one-dimensional coupled physical-biogeochemical model, together with reanalysis of the available data, are used to provide a new perspective for identification and interpretation of the suboxic layer (SOL) of the Black Sea. While the lower boundary appears to be stable at sigma(t) approximate to16.15 +/-0.10 kg m(-3), the upper boundary is found not to be isopycnally uniform as asserted previously. It is found to vary depending on the intensity of vertical diffusive and advective oxygen fluxes across the oxycline. Its position, therefore, does not always correspond to a distinct density surface irrespective of the circulation characteristics. Instead, it changes from sigma(t) approximate to 15.55 +/- 0.1 in cyclonic to sigma(t) approximate to 15.9 +/- 0.1 kg m(-3) in anticyclonic regions, whereas its position in the peripheral Rim Current transition zone occurs at intermediate density values. These findings imply that vertical oxygen variations cannot be expressed in terms of density without taking into account physical characteristics of the water column. The presence of very strong density stratification is found to prevent ventilation of the SOL. Even intense turbulent mixing generated by a large buoyancy loss during an exceptionally cold winter season is unable to generate sufficiently dense water to overturn and temporarily supply oxygen into the suboxic zone.


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Climate data on surface atmospheric variables, sea surface temperature and computed air-sea fluxes are analysed to describe comparative surface climatolo gies of the 'Seas of the Old World' (Black, Caspian and Mediterranean Seas) and to investigate their interannual and interdecadal variability. Based on these analyses, differences and similarities between climates of these basins and their relationships to other global systems are identified. Empirical Orthogonal Function (EOF) Analysis is used to study sp...
Citation Formats
T. Oguz, “Role of physical processes controlling oxycline and suboxic layer structures in the Black Sea,” GLOBAL BIOGEOCHEMICAL CYCLES, pp. 0–0, 2002, Accessed: 00, 2020. [Online]. Available: