Calculation of Hydrophysical Fields with Assimilation of Observational Data in the Northern Part of the Black Sea in Autumn 2016

The paper analyzes the results of calculation of the circulation and thermohaline water structure based on a three-dimensional nonlinear hydrodynamic model and hydrological data from a survey, carried out in the northern part of the Black Sea in autumn 2016. We used a high spatial resolution (horizontal grid ~1.6 × 1.6 km and 27 vertical layers) model and realistic atmospheric forcing. The assimilation procedure of observational data was based on a modified Kalman filter taking into account the heterogeneity and anisotropy of estimation error of the temperature and salinity fields. The calculated fields of currents were characterized by eddies and jet currents. The following circulation features were observed in the northern part of the Black Sea: an intense jet of the Black Sea Rim Current along the Crimean coast, anticyclonic eddies with a radius of about 30 km near Sevastopol and in the western part of the region, a cyclonic eddy with a radius of about 40 km between 34.5 and 35.5 E, anticyclonic eddies with a radius of about 25 km along the Crimean coast. Eddy formations of different scales and different signs of rotation were obtained (in the Kalamitsky Bay, in the eastern part and along the eastern coast of the Crimea), when the current flowed around irregularities of the coastline and the bottom relief in the coastal zone. The correlation between the formation of zones of lower and higher temperature relative to adjacent waters and the location of features in the field of current (in particular, the correspondence of zones with warmer desalinated water to the anticyclonic formations) was noted from the analysis of the reconstructed thermohaline fields.