Purpose. The study is purposed at analyzing the adequacy of reconstruction of mass, heat and salt transfer processes through the Bosphorus Strait based on the results of numerical simulation of joint circulation of the Euxine Cascade waters involving a simplified description of the strait due to the model spatial resolution.

Methods and Results. A regional configuration for the NEMO model (spatial resolution is about 1 km) which allows simulating the meso- and submeso-scale variability of hydrophysical fields in the Euxine Cascade seas is used. It is briefly described. The numerical experiment covers the period 2008–2009. The salinity and current velocity fields in the strait cross-section reconstructed in the experiment confirm a two-layer structure of water circulation, i.e. the presence of upper and lower Bosphorus currents. Besides, they show the availability of periods of complete or partial blocking both the upper and lower currents. Despite a somewhat rough configuration of the strait, the reconstructed salt exchange features are in good agreement with the similar ones obtained on the basis of a finite-element model with a higher spatial detailing in the strait, and as for temperature, the agreement is to some extent worse. At the same time, the reconstructed current velocities show a fairly accurate correspondence of the blocking events when compared to the earlier performed measurements.

Conclusions. The previously revealed mechanism for maintaining the upper Bosphorus Current in winter conditioned by a rise of the Black Sea level in the Bosphorus region due to the Rim Current intensification has been confirmed. The model qualitatively correctly describes the strait response to the changes both in wind forcing and seawater density in the vicinity of the northern and southern inlets to the strait. Blockings of the upper Bosphorus Current occur and can be induced by the intensification of currents in the Marmara Sea due to the wind forcing and subsequent weakening of the Black Sea Rim Current. In a winter-spring period, the Marmara Sea circulation weakens, and one can observe the reverse phenomena in which the lower Bosphorus current blockings take place.