Estimating the quality of the retrieval of the surface geostrophic circulation of the Black Sea by satellite altimetry data based on validation with drifting buoy measurements

Combined measurements of satellite altimeters make it possible to determine anomalies of the sea level of the Black Sea on a regular grid with a high spatial resolution 1/8°. In this work arrays of total geostrophic velocities of currents in the Black Sea basin are retrieved and compared with drifter measurements of current velocities for 1999–2007. The comparison is performed both for the whole array of drifter measurements (～110000 measurements) and individually for each drifter. To retrieve the velocities, two different arrays of mean dynamic topography (MDT) are used: synthetic and climatic mean dynamic topography. The comparison results demonstrate that using synthetic MDT is preferable for calculating geostrophic velocities. Velocities calculated by from satellite altimetry data agree with velocities obtained by in-situ data.     

The North Atlantic Oscillation: A dominant factor in variations of oceanic circulation systems of the Atlantic Ocean

On the basis of altimetry data, the dynamics of the interaction between the subtropical anticyclonic (SA) and subpolar cyclonic (SC) gyres of the North Atlantic is considered. It is shown that the westerlies in the lower troposphere represented by the North Atlantic Oscillation (NAO) index are the main factor responsible for the dynamics of the gyres, which controls the inflow of warm Atlantic water into the Polar basin.     

Comparing satellite and meteorological data on wind velocity over the Black Sea

Wind-velocity data obtained from in situ measurements at the Golitsyno-4 marine stationary platform have been compared with QuikSCAT scatterometer data; NCEP, MERRA, and ERA-Interim global reanalyses and MM5 regional atmospheric reanalysis. In order to adjust wind velocity measured at a height of 37 m above the sea surface to a standard height of 10 m with stratification taken into account, the Monin–Obukhov theory and regional atmospheric reanalysis data are used. Data obtained with the QuikSCAT scatterometer most adequately describe the real variability of wind over the Black Sea. Errors in reanalysis data are not high either: the regression coefficient varies from 0.98 to 1.06, the rms deviation of the velocity amplitude varies from 1.90 to 2.24 m/s, and the rms deviation of the direction angle varies from 26° to 36°. Errors in determining the velocity and direction of wind depend on its amplitude: under weak winds (<3 m/s), the velocity of wind is overestimated and errors significantly increase in determining its direction; under strong winds (>12 m/s), its velocity is underestimated. The influence of these errors on both spatial and temporal estimates of the characteristics of wind over the Black Sea is briefly considered.     

A two-channel method for retrieval of the Black Sea surface temperature from Landsat-8 measurements

Izvestiya, Atmospheric and Oceanic Physics - The present work is devoted to the development of a retrieval algorithm for the sea surface temperature from the two-channel measurements of the...     

Assimilation of the climatic hydrological data in the σ-coordinate model of the black sea by the algorithm of adaptive statistics

We realize the algorithm of adaptive statistics of forecasting errors for the assimilation of the climatic fields of temperature and salinity in the σ-coordinate model of the dynamics of the Black Sea. The principal relations of this algorithm and its simplified version based on the Kalman filter are presented. The distinctive features of realization of the algorithm specified by the model are discussed. We also present the results of comparison of the hydrophysical fields of the Black Sea reconstructed according to the algorithm of adaptive statistics and a simplified scheme of assimilation of the climatic data. It is shown that the dependence of sources in the transport equations (heat and salt diffusion) on the four-dimensional variances of forecasting errors and threedimensional measurement errors enables one to reconstruct the mutually adapted climatic parameters of the sea more exactly.     

Interaction between Rossby Waves and a Jet Flow: Basic Equations and Verification for the Antarctic Circumpolar Current

Izvestiya, Atmospheric and Oceanic Physics - Abstract—The article focuses on the interaction of Rossby waves in the ocean with zonal jet flows. A new approach is proposed to show that...     

Seasonal and interannual variability of vertical turbulent exchange coefficient in the Black Sea pycnocline in 2013–2016 and its relation to variability of mean kinetic energy of surface currents

Ocean Dynamics - In this paper, we analyze seasonal and interannual variability of vertical turbulent diffusion coefficient (Kt). Our calculations are based on the time series from 2013 to 2016,...     

Properties of the Vertical Distribution of Diurnal Temperature Variations in Different Seasons in the Black Sea Based on the NEMO Model Data

Izvestiya, Atmospheric and Oceanic Physics - A study has been performed for the Black Sea basin investigating the properties of the vertical distribution of the daily temperature variation in...     

Characteristics of topographic submesoscale eddies off the Crimea coast from high-resolution satellite optical measurements

Ocean Dynamics - Long-term arrays of satellite optical measurements of Landsat-5,7,8 and Sentinel-2 were used to describe the characteristics of submesoscale eddy (SE) dynamics in different parts...     

Distinctive features of circulation of waters in the region of the Zmeiny Island under the action of winds of various directions

We use mathematical simulation to study the response of the sea in the region of the Zmeiny Island to the action of winds of various directions. We describe the processes of reconstruction of circulation and thermohaline structure of waters and, in particular, the location and dimensions of the zones of upwelling and downwelling caused by water surges depending on the direction of the wind. Translated by Peter V. Malyshev and Dmitry V. Malyshev