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1.
Izvestiya, Atmospheric and Oceanic Physics - This paper investigates the stability of a jet flow with a piecewise linear velocity profile in a rotating stratified atmosphere. The linearized set of... 相似文献
2.
Geodynamic aspects of the development of offshore oil and gas deposits: Case study of Barents region
Geodynamic aspects of the development of offshore deposits in the Russian sector of Barents region are considered. The main
technogenic geohazards at oil hydrocarbon extraction are shown to be land subsidence and earthquakes. A concept of studying
geodynamic manifestations is substantiated. This concept is based on the evolution of oil-and-gas-producing enterprise with
appropriate portion of geological environment, regarded as a complex open natural-engineering system. The geodynamic situation
at the Shtokman gas-condensate field was simulated using a mathematical model. The model showed some regularities in the deformation
of the fluid-bearing massif because of gas extraction, including the up to 30% volumetric compaction of the production strata,
resulting in a regression deflection (subsidence) of seabed and considerable subhorizontal deformations and displacements
of bottom rock beds. The specific features of gas pipeline laying from the Shtokman field through Murmansk province are discussed,
and the structure of geodynamic monitoring is proposed. Substantiation is given to the need to carry out special geodynamic
studies in the Barents region with the aim to ensure operation geosafety and stability of structures of oil-and-gas facilities
and pipeline transportation of hydrocarbons materials. 相似文献
3.
The nonlinear dynamics of long-wave perturbations of the inviscid Kolmogorov flow, which models periodically varying in the horizontal direction oceanic currents, is studied. To describe this dynamics, the Galerkin method with basis functions representing the first three terms in the expansion of spatially periodic perturbations in the trigonometric series is used. The orthogonality conditions for these functions formulate a nonlinear system of partial differential equations for the expansion coefficients. Based on the asymptotic solutions of this system, a linear, quasilinear, and nonlinear stage of perturbation dynamics is identified. It is shown that the time-dependent growth of perturbations during the first two stages is succeeded by the stage of stable nonlinear oscillations. The corresponding oscillations are described by the oscillator equation containing a cubic nonlinearity, which is integrated in terms of elliptic functions. An analytical formula for the period of oscillations is obtained, which determines its dependence on the amplitude of the initial perturbation. Structural features of the field of the stream function of the perturbed flow are described, associated with the formation of closed vortex cells and meandering flow between them. As a supplement, an asymptotic analysis of nonlinear dynamics of long-wave perturbations superimposed on a damped by small viscosity Kolmogorov flow (very large, but finite Reynolds numbers) is made. It is strictly shown that all velocity components of the perturbed flow remain bounded in this case. 相似文献
4.
M. V. Kalashnik O. G. Chkhetiani G. D. Chagelishvili 《Izvestiya Atmospheric and Oceanic Physics》2018,54(4):305-312
Edge baroclinic waves are generated in a geostrophic flow with a vertical shear near a solid surface. The study investigates a new class of baroclinic waves in flows with horizontal and vertical shears and a linear distribution of potential vorticity. It is shown that taking account of the horizontal shear leads to the appearance of new features of wave dynamics. These include the nonmodal growth of energy in the initial stage of development, the time dependence of the vertical wave scale, and the possibility of generation of stationary or blocked waves. The horizontal shear makes the mechanism of generation of baroclinic waves by initial vortex perturbations more efficient. One important feature is associated with vortex paths, which are formed by the superposition of a baroclinic wave on the flow with horizontal shear. 相似文献
5.
The problem of finding optimal perturbations, which are perturbations with a maximum ratio of the final energy to the initial energy, is considered in the Eady model of baroclinic instability. The solution to the problem uses explicit expressions for the energy functional, which are functions of parameters of an initial perturbation. For perturbations with zero potential vorticity, the basic parameters are the amplitudes of the initial buoyancy distributions at the boundaries of the atmospheric layer and a phase shift between these distributions. Dependences of the optimal phase shift and maximum energy ratio on the wave number and time optimization are determined using an analysis for extremum. The parameters of the optimal perturbations are compared with those of the growing normal modes. It is found that only one exponentially growing mode is an optimal perturbation. 相似文献
6.
M. V. Kalashnik A. F. Nerushev R. V. Ivangorodsky 《Izvestiya Atmospheric and Oceanic Physics》2017,53(2):156-163
Wind-speed distributions in atmospheric upper air jet streams have a horizontal asymmetry: the wind shear on the northern (cyclonic) side of the jet is larger than that on the southern (anticyclonic) side. The paper suggests an explanation of this feature on the basis of the theory of nonlinear geostrophic adjustment. Simple theoretical estimates are obtained for the asymmetry coefficient of the speed profile. It is shown that the asymmetry increases with the Rossby number (with a jet-stream velocity). Results of the statistical analysis of the horizontal asymmetry of jet streams from Earth’s satellite measurements are described. 相似文献
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8.
M. V. Kalashnik 《Izvestiya Atmospheric and Oceanic Physics》2011,47(4):439-444
Cyclone-anticyclone asymmetry in a rotating fluid results in vortices with cyclonic rotation being attenuated more rapidly than vortices with anticyclonic rotation due to the Ekman bottom friction. To explain this effect, some authors invoked rather complex integral (averaged along the vertical) models with the parametrization of nonlinear friction. A simple analytical model, free of the procedure of formal averaging and based on a separate consideration of the equations for external flow in the nonviscous region and internal flow in the boundary layer, is investigated in this work. The corresponding equations are written in the so-called geostrophic momentum approximation, which makes it possible to take into account the nonlinear advective mass transport in the boundary layer at small Rossby numbers. The nonlinear equation of the hyperbolic type for the tangential velocity, which describes the process of attenuation of an axisymmetric vortex, is obtained from the condition of total mass conservation. Based on the solutions to this equation, it was shown that distinctions in the character of vortex attenuation are caused by deviations from the geostrophic regime in the nonviscous region. It was established that the concentration (compression) of anticyclonic vortices and the extension of cyclonic ones take place in the process of attenuation. 相似文献
9.
O. G. Chkhetiani M. V. Kalashnik L. Kh. Ingel’ 《Izvestiya Atmospheric and Oceanic Physics》2013,49(2):121-127
The problem of stationary convective flows over a nonuniformly heated wavy surface is studied in the context of a simplified analytical model. It is shown that the horizontally periodic heating of such a surface can lead to a “thermal wind” effect, i.e., the generation of a uniform horizontal flow far from the surface. 相似文献
10.
M. V. Kalashnik 《Izvestiya Atmospheric and Oceanic Physics》2013,49(2):217-228
The process of propagation and trapping of inertial gravity wave (IGW) packets in oceanic shear flows is studied in the geometric-optics approximation (ray theory). It is shown that wave trapping in strong stable stratification occurs in the region of anticyclonic (horizontal) velocity shear in a narrow frequency range on the left side of the inertial frequency. Beyond this range, the packet (ray) is either reflected from a cyclonic shear layer or propagates freely through the shear layer. The basic equations of ray theory are analyzed qualitatively, and analytical expressions are derived for freely propagating and trapped rays. The influence that vertical shear exerts on the ray behavior is also investigated. It is shown that two-dimensional ray focusing occurs as the velocity profile decreases with depth, so that rays concentrate along a specific latitude. 相似文献