Modelling of the spectral characteristics of the wind wave envelope

A method applied for the determination of the statistical characteristics of the wind wave envelope is considered. It is shown that the correlation function envelope for a normal random process defines the basic properties of the process envelope and it can be expressed through the spectrum width. No limitations are imposed on the form or the width of the spectrum. The model is effective for a developing and steady sea disturbance when the attenuation of the temporal correlation function can be approximated by an exponent. Numerical computations and experimental results for typical cases of sea disturbance are compared.Translated by Mikhail M. Trufanov.     

Relationship between the Beam Attenuation Coefficient and the Concentration of Suspended Matter in Black-Sea Waters

By using the results of simultaneous measurements of the beam attenuation coefficient and the concentration of suspended matter in water samples, we deduce the relationships between these parameters for wavelengths of 640, 660, and 677 nm. The proposed formulas are used for the evaluation of the concentration of suspended matter according to the data of optical measurements performed in cruises of research vessels. We present two maps of the distribution of suspended matter plotted for the north part of the sea in November–December 1991 and for the south part of the sea in July 1992.     

Numerical simulations of three-dimensional magnetic swirls in a solar flux-tube

We aim to numerically study evolution of Alfv′en waves that accompany short-lasting swirl events in a solar magnetic flux-tube that can be a simple model of a magnetic pore or a sunspot. With the use of the FLASH code we numerically solve three-dimensional ideal magnetohydrodynamic equations to simulate twists which are implemented at the top of the photosphere in magnetic field lines of the flux-tube. Our numerical results exhibit swirl events and Alfv′en waves with associated clockwise and counterclockwise rotation of magnetic lines, with the largest values of vorticity at the bottom of the chromosphere, and a certain amount of energy flux.     

Hydrooptical Characteristics of Subsatellite Test Ranges in the Mediterranean and Black Seas According to the Data of Investigations Performed by the R/V Gorizont in 1998

Hydrooptical investigations were performed for three subsatellite test ranges located near the Rhodes Island in the Levant Sea, near Dardanelles in the north part of the Aegean Sea, and near the Crimean Peninsula in the northwest part of the Black Sea. In the course of observations, we measured the beam attenuation coefficient, the depth of visibility of the Secchi disk, and the color of water. These data are used to characterize the space and time variability of the optical properties of water in the investigated regions.     

Characteristics of Underwater Irradiation in the Black Sea in Spring (1993 and 1995)

We present the data on the values of the coefficients of vertical attenuation and diffusive reflection of light in the Black Sea in spring 1993 and 1995, compute the depths of one-percent quantum irradiation and the parameter Μ specifying the fraction of attenuation of directed light as a result of scattering: Μ = σ/ɛ, and compare the characteristics of underwater irradiation in the sea in different seasons for 1989–1995. __________ Translated from Morskoi Gidrofizicheskii Zhurnal, No. 3, pp. 44–48, May–June, 2005.     

Characteristics of a Cup Anemometer and a Procedure of Measuring the Wind Velocity

On the basis of the data of laboratory, model, and field investigation of the characteristics of a proposed cup anemometer, we obtain the following results: the distance constant is equal to 0.32 m with a mean-square deviation of 0.05 m, which is smaller than for the other anemometers of this type by an order of magnitude, the dynamic characteristics of the anemometer are linear for typical conditions of atmospheric turbulence, the variance and spectrum of noises (as a result of transformation of pulsed signals at the output of the anemometer) are described by universal functions with known parameters, the transmission bandwidth is approximately equal to 2 Hz for wind velocities lower than 5 m/sec and up to 5 Hz for higher wind velocities, and the errors of measurements of the mean wind velocity and the characteristics of the longitudinal component of velocity are approximately equal to 1 and 3%, respectively. The dimensions and weight of the anemometer are quite small, which enables one to perform long-term measurements of the characteristics of wind velocity for all types of platforms within broad ranges of hydrometeorological conditions.     

On the possible generation of low-frequency microseisms by internal waves in the ocean

The conditions under which the interaction between internal waves and the rough bottom topography may be the reason for synchronous fluctuations of pressure at the bottom have been studied. Disturbances of the depth are assumed to be small compared with the mean depth of the ocean, and the Väisälä-Brunt frequency is constant. It is shown that synchronous fluctuations of pressure exist with a frequency equal to that of internal waves. The amplitude of pulsations can be approximately an order lower than the amplitude of fluctuations generated by standing surface waves. However, local maxima can exist in the low-frequency minimum of the spectrum of microseisms (in the range of 20–1000 s).Translated by Mikhail M. Trufanov.     

Plate boundaries in the Far East region of Russia (from GPS measurement,seismic-prospecting,and seismological data)

The recent geodynamics of the Far East region of Russia is considered, where three large tectonic plates converge—Eurasian, North American, and Pacific, as well as several microplates—Okhotsk, Bering, and Amurian—have been hypothesized to exist. The available data on the position of the plate boundaries, the relative plate rotation poles, and the regional seismicity were analyzed, and parameters of plate motion models for northeastern Russia were determined in this study. The regional deep structure was investigated, using data obtained by different geophysical methods. The results of observations of the Magadan–Vrangel Island profile by deep seismic sounding (DSS), common-depth point (CDP) method, and correlation refraction method (CRM) are presented.