Evolution of the Cold Intermediate Layer in the Black Sea According to the Results of Assimilation of Climatic Data in the Model

We present the results of analysis of the seasonal variability of the climatic cold intermediate layer based on a complex approach with the use of series of successive changes in the hydrophysical parameters computed according to the model with assimilation of the climatic fields of temperature and salinity. We analyze some mechanisms of formation of the cold intermediate layer. It is discovered that the layer of cold waters, which is continuous after regeneration and transformation in the entire deep-water area of the sea, becomes discontinuous at the end of the year (October–November). One of the possible mechanisms responsible for the appearance of discontinuities is discussed.     

Numerical experiment on the computation of the equatorial circulation on the basis of a conservative model

A finite-difference system of motion equations for a baroclinic ocean with an irregular bottom is developed on the basis of the box method and the method of indefinite coefficients. The numerical model is shown to possess the property of conserving momentum, mass, and energy. In the case of barotropic motion, the finite-difference scheme retains potential enstrophy. A numerical experiment on the adaptation of hydrophysical fields in the Equatorial Atlantic in summer was carried out within the framework of the model developed. We managed to obtain a series of features of the equatorial circulation when the coefficients of turbulent exchange and diffusion were small enough.Translated by Mikhail M. Trufanov.     

A Procedure of Reconstruction of the Climatic Seasonal Circulation in the Black Sea Based on the Assimilation of Hydrological Data in the Model

We propose a procedure of reconstruction of the continuous (in time) climatic annual behavior of circulation in the Black Sea based on the successive assimilation of the climatic distributions of temperature and salinity in the complete nonlinear model. We use monthly average arrays interpolated for each day of a year by expanding in harmonic functions of time. Various procedures aimed at the assimilation of data are studied by taking into account the variance of measurement errors. Our main attention is given to the analysis of qualitative and quantitative characteristics of vertical motions in the sea depending on the quality of the data and parameters of the model. The main version of calculations is illustrated by the maps of annual variability of the fields of sea level, horizontal currents, and vertical velocity.     

Investigation of the absolute instability of currents in oceanic gyres

In the approximation of geometric optics, we study the absolute instability of currents in oceanic gyres. It is shown that absolute instability is observed in the case where the most unstable mode of wave motion is stationary. Our results qualitatively agree with the data of numerical experiments aimed at the simulation of the synoptic variability of large-scale oceanic gyres.Translated from Morskoi Gidrofizicheskii Zhurnal, No. 5, pp. 3–13, September–October, 2004.This revised version was published online in May 2005 with corrections to cover date.     

Hydrological Regime and Morphodynamics of the Yangtze River Mouth Area

The features of the hydrological regime, modern morphological structure, fluviomorphological processes, and the history of formation of the Yangtze River mouth area are discussed. The influence of the huge river water and sediment runoff and tides on the hydrological and morphological processes in the Yangtze River mouth is shown. The possible impact of construction of the large waterworks Three Gorges on the hydrological and morphological processes in the Yangtze River mouth is roughly evaluated.     

The effect and precursors of the earthquake of August 28, 2008, in the vertical component of the electric field in Lake Baikal

Doklady Earth Sciences -     

Seasonal and interannual variability of Black Sea hydrophysical fields reconstructed from 1971–1993 reanalysis data

We pioneered a retrospective analysis of Black Sea hydrophysical fields for the period from 1971 to 1993. We describe a reanalysis algorithm based on the assimilation (in a σ-coordinate circulation model) of observed temperature and salinity data obtained on hydrophysical test areas. The thickness of the cold intermediate layer (CIL) and its freezing capacity for 1985 to 1993 were found to be increasing. At the levels of 0, 50, 75, and 100 m, the tendency of variations in annual values of level-averaged temperature is negative. At the level of 200 m and deeper, the linear trends of the interannual course of temperature are positive. We found that the linear trends of interannual variations in salinity are negative in the upper layer of 0 to 50 m and positive at 75 m and deeper. The sea-water circulation in the layer from 0 to 300 m was observed to be maximum in February–March and minimum in September–October. The characteristic of the linear trend of interannual variations in the kinetic energy of currents averaged over the sea surface is negative, while its value is positive in the layer from 50 to 100 m. Some factors responsible for the formation of hydrophysical fields in the sea and their seasonal and interannual variations were indicated. We revealed that there is a qualitative resemblance between seasonal and interannual variations [4, 26] in temperature, salinity, and kinetic energy.     

Baikal Deep-Water Monitoring—New Results

Izvestiya, Physics of the Solid Earth - Abstract—The vertical component of the electric field Ez in the water column can have an almost zero telluric component, which allows effective...