Seasonal Variations and Transformations of Climatic Currents with Depth on the Basis of Assimilation of New Climatic Data on Temperature and Salinity in a Model of the Black Sea

Abstract

Demyshev, V. V. Knysh, and N. V. Inyushina UDC 551.465 The seasonal climatic circulation of the sea reconstructed on the basis of assimilation of new arrays of many-year average hydrological data in a model is analyzed. Five layers are discovered in the structure of climatic currents in the sea in depth: the surface Ekman layer (& 10 m), a layer with small vertical gradients of the kinetic energy (& 10-60 m), a layer with relatively high vertical gradients of the kinetic energy (& 60-150 m), a layer with gradual decrease in the kinetic energy and intensification (from 250-350 m) of the east cyclonic gyre and Batumi anticyclonic eddy (& 150-1000 m), and an abyssal layer characterized by an almost barotropic velocity (& 1000-2000 m).The specific features of the seasonal evolution of currents at these depths are investigated. It is shown that the key role in the formation of deep-water circulation of the sea is played by the south east flow, east cyclonic gyre, and Batumi anticyclonic eddy.Marine Hydrophysical Institute, Ukrainian Academy of Sciences, Sevastopol.

Assimilation of climatic data in a model of circulation of waters in the Black Sea with regard for the space and time behavior of the variances and cross-covariance functions of forecast errors

“…1, the period of stabilization was equal to 150 days. As the initial conditions, we took the fields of temperature, salinity, current velocities, and sea level obtained as a result of numerical calculations performed with assimilation in the model solely of the climatic arrays of temperature and salinity [8].…”

“…The comparison of the profiles of coefficients specified by relations (7) and (8) in the case of their dependence solely on the vertical coordinate and time (without taking into account the dynamics of waters [4]) with the profiles of these coefficients averaged over any given depth (with regard for the dynamics of the sea) in different seasons shows that the amplitudes of the latter are much lower. In this case, the influence of the data of observations in the model decreases and the role of the effect of mutual adaptation of the hydrophysical parameters of the sea increases.…”

“…The algorithm of assimilation of the climatic data was tested by using of a nonlinear numerical model of dynamics of the sea presented in [7,8]. The specific features of the model, the values of the parameters, and the boundary conditions typical of the Black-Sea basin are presented in [4].…”

Vertical structure of the field of current velocities in the northwest part of the Black Sea based on the LADCP data for May 2004

“…The results of numerical modeling performed on the basis of the climatic data give a smoothed picture of circulation but, at the same time, reveal noticeable space shifts of the jet of Rim Current from season to season [1]. The standard hydrological field surveys reveal more pronounced variations of the space-and-time characteristics of the dynamics of waters [2].…”

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

“…In a series of works published in recent years [1][2][3][4], various procedures aimed at the reconstruction of the seasonal hydrophysical fields in the Black Sea on the basis of assimilation of the climatic temperature and salinity fields in the model of circulation were proposed and realized. The analyses carried out in these works are based on the numerical nonlinear model developed at the Marine Hydrophysical Institute (MHI) of the Ukrainian National Academy of Sciences and described in detail in [5].…”