**4. Conclusions**

The important outcome of the study is that atmospheric fluxes can affect the circulation of both the surface and deepwater layers of the Black Sea, and the choice of atmospheric forcing data can be decisive for the correct modeling of hydrophysical fields in the entire basin. As was determined through numerical analysis, with a significant influence of wind forcing, both the upper layer circulation and the deepwater dynamics in the Black Sea depend on the characteristics of the atmosphere. Despite strong density stratification and difficult vertical exchange with deep layers, the atmospheric forcing also affects the circulation at a horizon of 200 m and deeper. Thus, mesoscale features of the model dynamics near the continental slope, such as subpycnocline undercurrents detected from the ARGO observations in the northeastern part of the sea, appear only when using ERA5 forcing. Additionally, the Black Sea thermohaline structure is more accurately reconstructed under ERA5 forcing, and this was confirmed by the TS-measurement data. Atmospheric fluxes in ERA5 were more likely to be intense compared to SKIRON. Thus, for more accurate modeling of Black Sea circulation and its subsequent application for complex studies, from the two widely used meteorological datasets, the use of ERA5 atmospheric forcing data is recommended rather than SKIRON.

**Author Contributions:** Conceptualization, O.D. and N.M.; forcing preparation, modeling, validation, and visualization O.D.; hydrophysical analysis, N.M.; writing—original draft preparation, O.D. and N.M.; writing—review and editing, O.D. and N.M. All authors have read and agreed to the published version of the manuscript.

**Funding:** Numerical simulations and validation of the results were funded by the Russian Science Foundation under Grant 22-77-10056 (https://rscf.ru/en/project/22-77-10056/, accessed on 10 March 2023). Observation data processing was carried out within MHI State assignment on theme № FNNN-2021-0004. Estimation of the atmospheric forcing effect on the Black Sea deepwater circulation was supported by the Russian Science Foundation Grant No. 22-17-00150 (https://rscf.ru/en/ project/22-17-00150/ (accessed on 10 March 2023)).

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** The datasets generated and analyzed during the current study are available from the MHI administration upon reasonable and/or special request.

**Acknowledgments:** The authors are grateful to the developer of the MHI-model, Demyshev S.G., for the opportunity to use the model in the experiments.

**Conflicts of Interest:** The authors declare no conflict of interest.
