Solitary Vortical Structures Research Articles

Formation of Nonlinear Solitary Vortical Structures by Drift and Ion-Acoustic Waves in Electron-Positron-Ion Plasmas

Formation of Nonlinear Solitary Vortical Structures by Drift and Ion-Acoustic Waves in Electron-Positron-Ion Plasmas

Formation of Nonlinear Solitary Vortical Structures by Coupled Electrostatic Drift and Ion-Acoustic Waves

Propagation of coupled electrostatic drift and ion-acoustic waves (DIAWs) is presented. It is shown that nonlinear solitary vortical structures can be formed by low-frequency coupled electrostatic DIAWs. Primary waves of distinct (small, intermediate and large) scales are considered. Appropriate set of 3D equations consisting of the generalized Hasegawa–Mima equation for the electrostatic potential (involving both vector and scalar nonlinearities) and the equation of motion of ions parallel to magnetic field are obtained. According to experiments of laboratory plasma mainly focused to large scale DIAWs, the possibility of self-organization of DIAWs into the nonlinear solitary vortical structures is shown analytically. Peculiarities of scalar nonlinearities in the formation of solitary vortical structures are widely discussed.

Shear flow driven Rossby-Khantadze electromagnetic planetary vortices in the ionospheric E-layer

A system of equations describing the nonlinear interaction of coupled Rossby-Khantadze electromagnetic waves with a sheared zonal flow in the Earth's ionospheric E-layer is obtained. For the linear regime the corresponding region of phase velocities is analyzed and the appropriate stability condition of zonal flow is deduced. It is shown that the sheared zonal flow may excite solitary vortical structures in the form of a row of counter-rotating vortices whose amplitudes decrease with the increase of the zonal flow parameter. This conclusion is consistent with the stabilizing idea of a sheared zonal flow. The possibility of an intense magnetic-field generation is shown.

Rossby–Khantadze electromagnetic planetary vortical motions in the ionospheric E-layer

AbstractIt is shown that in the earth's conductive ionospheric E-region, large-scale ultra low-frequency Rossby and Khantadze electromagnetic waves can propagate. Along with the prevalent effect of Hall conductivity for these waves, the latitudinal inhomogeneity of both the earth's angular velocity and the geomagnetic field becomes essential. Action of these effects leads to the coupled propagation of electromagnetic Rossby and Khantadze modes. Linear propagation properties of these waves are given in detail. It is shown that the waves lose the dispersing property for large values of wave numbers. Corresponding nonlinear solitary vortical structures are constructed. Conditions for such self-organization are given. It is shown that nonlinear large-scale vortices generate the stronger pulses of the geomagnetic field than the corresponding linear waves. Previous investigations are revised.

Acoustic-gravity waves in the Earth's ionosphere

Taking into account the existence of charged particles in the Earth's ionosphere the propagation of acoustic-gravity waves is investigated. The influence of the Coriolis force is also taken into account. The weakly ionized ionospheric D, E, and F-layers are considered. The existence of a cut-off frequency at 2 Ω 0 ( Ω 0 is the value of the angular velocity of the Earth's rotation) is noted. It is shown that the linear waves are damped because of the Pedersen conductivity. When the acoustic-gravity waves are excited by external events (volcanic eruptions, earthquakes, lightning strikes, etc.) their amplitudes grow until self-organization of these waves into nonlinear vortex solitary structures is admitted. Taking into account the interaction of the induced ionospheric current with the geomagnetic field the governing nonlinear equations are deduced. The formation of dipole vortex solitary structures of low-frequency internal gravity waves is shown for the stable stratified ionosphere. The dynamic energy equation for such nonlinear structures is obtained. It is shown that nonlinear solitary vortical structures damp due to Joule losses.

Localized magnetized Rossby structures under zonal shear flow in the ionospheric E-layer

Taking into account nonlinear interaction of magnetized Rossby waves with zonal shear flow in the Earth's ionospheric E-layer modified by inhomogeneous geomagnetic field and sheared zonal flow Charney equation is obtained. The appropriate region of linear phase velocities is analyzed and the stability condition of zonal flows is obtained. In case of nonlinear regime the appropriate compatibility condition is obtained and its independence on zonal shear flows is shown. It is shown that zonal shear flow may support the existence of solitary vortical structures. Owing to carried out analysis different from dipole structures new class of nonlinear solitary vortical structures is found.

First- and second-order accurate implicit difference schemes for the numerical resolution of the generalized Charney–Obukhov and Hasegawa–Mima equations

First- and second-order accurate implicit difference schemes for the numerical solution of the nonlinear generalized Charney-Obukhov and Hasegawa-Mima equations with scalar nonlinearity are constructed. On the basis of numerical calculations accomplished by means of these schemes, the dynamics of two-dimensional nonlinear solitary vortical structures are studied. The problem of stability for the first-order accurate semi-discrete scheme is investigated. The dynamic relation between solutions of the generalized Charney-Obukhov and Hasegawa Mima equations is established. It is shown that, contrary to existing opinion, the scalar nonlinearity in the ease of the generalized Hasegawa-Mima equation develops monopolar anticyclone, while in case of the generalized Charnev -Obukhov equation it develops monopolar cyclone.

Investigation and numerical resolution of initial-boundary value problem for the generalized Charney–Obukhov and Hasagewa–Mima equations

In the present work, first-order accurate implicit difference schemes for the numerical solution of the nonlinear generalized Charney–Obukhov and Hasegawa–Mima equations with scalar nonlinearity are constructed. On the basis of numerical calculations accomplished by means of these schemes, the dynamics of a two-dimensional nonlinear solitary vortical structures is studied. For the considered equations the initial-boundary value problem is set when at the initial moment the solution in the form of solitary dipole structure is taken. For this problem uniqueness of the solution in case of periodic boundary conditions is proved. The dynamic relation between solutions of the generalized Charney–Obukhov and Hasegawa–Mima equations is established. It is shown that, in spite of the existing opinion, the scalar nonlinearity in case of the generalized Hasegawa–Mima equation develops monopolar anticyclone, while in case of the generalized Charney–Obukhov equation develops monopolar cyclone.

Self-organization of planetary electromagnetic waves in the E-region of the ionosphere

A physical mechanism for the generation of slow and fast electromagnetic-type planetary waves due to standing factor—latitude variation of geomagnetic field—in the dissipative E-region of the ionosphere is suggested. It has been shown that slow waves are generated due to the dynamo-field in the ionosphere, and fast waves by the vortical electric field. The slow electromagnetic wave is analog to the Rossby planetary wave; the fast electromagnetic wave is a new mode of natural oscillations of the E-region of the ionosphere. Linear waves propagate along the parallel west and east directions in the dynamo-region of the ionosphere against a background of the mean zonal flow. Phase velocity of the fast waves is a few km s −1 , oscillation frequencies are in the frequency band of 10 −2– 10 −4 s −1 and the wavelength is of the order of 10 3 km and higher. Phase velocities of the slow waves and local winds are at the same order of magnitude, the frequency band is 10 −4– 10 −5 s −1 and wavelength is of 10 3 km and higher order. Fast waves generate intense magnetic fields in order of a few hundred nanotesla (nT); slow waves—a few tens of nT. In this paper the nonlinear theory of both fast and slow planetary electromagnetic waves in the E-region of the ionosphere is investigated for the first time. It was established that these perturbations are self-localized as nonlinear solitary vortical structures in the dynamo-region of the ionosphere move to the west (fast) and to the east (slow) against a background of the mean zonal flow. The nonlinear structure consists of cyclone–anticyclone-type mutual counter-clockwise-rotating vortices, which capture medium particles. Energy and enstrophy of these large-scale vortices are weakly attenuated and are long-lived. Vortical structures generate magnetic fields, which are an order of magnitude larger than those generated by the corresponding linear waves. Features and parameters of electromagnetic wavy structures are theoretically investigated and are in good agreement with the experimental data of large-scale ULF wavy perturbations observable in the ionosphere.

Nonlinear Alfven–Rossby vortical structures in the Earth's ionosphere

The influence of spatial inhomogeneity of the Earth's rotation on the Alfven perturbations is considered.The possibility of existence of new spatially localized joint Alfven–Rossby nonlinear solitary vortical structures in the Earth's ionosphere is shown. In the ideal magnetohydrodynamic approximation, corresponding system of nonlinear partial differential equations governing the dynamics of Alfven–Rossby waves is obtained. It is shown that, in the case of stationary propagation, it has the well-known spatially localized Larichev–Reznik type solution. It is suggested that such dynamic Alfven–Rossby nonlinear solitary vortical structures are responsible for so-called “magnetic days” in the Earth's atmosphere.

Solitary dipole vortices in the Earth's ionosphere

The influence of charged particles and the Earth's magnetic field on the possibility of the formation of solitary vortical structures in the different layers of the Earth's ionosphere is considered for the first time. It is shown that such influence manifests itself only in the E and F layers and leads to the destruction of the vortical dipole structures. Therefore longlived vortices mainly exist in the D layer of the atmosphere in the form of solitary dipole Rossby vortices. The nonlinear equations describing the vortical formation dynamics in the D, E and F layers are obtained.

Electron vortices in a nonneutral plasma in crossed E⊥H fields

Abstract Geometrical dimensions and electron densities of solitary vortical structures in a magnetized nonneutral electron plasma in crossed E ⊥ H fields have been experimentally determined. The process of their formation and evolution has been investigated.