Sinking of less dense water in the bottom Ekman layer formed by a coastal downwelling current over a sloping bottom

Laboratory experiments on the dynamics of a downwelling coastal current over a sloping bottom were conducted in a tank on a rotating platform. The current was generated by a source of stable water flow of the same density (barotropic case) or of lesser density (baroclinic case) compared with the surrounding water in the tank. It was found that even in the case of the baroclinic current, a less dense water downflow in the bottom Ekman layer was formed under certain conditions. At some moment, this downflow undergoes convective instability. Taking into account the results of the experiment, the parameters of the bottom Ekman layer on the continental shelf/slope of the Black Sea were preliminarily estimated and the possible sinking depth of less dense water was calculated.