Model of strong stationary vortex turbulence in space plasmas

Abstract. This paper investigates the macroscopic consequences of nonlinear solitary vortex structures in magnetized space plasmas by developing theoretical model of plasma turbulence. Strongly localized vortex patterns contain trapped particles and, propagating in a medium, excite substantial density fluctuations and thus, intensify the energy, heat and mass transport processes, i.e., such vortices can form strong vortex turbulence. Turbulence is represented as an ensemble of strongly localized (and therefore weakly interacting) vortices. Vortices with various amplitudes are randomly distributed in space (due to collisions). For their description, a statistical approach is applied. It is supposed that a stationary turbulent state is formed by balancing competing effects: spontaneous development of vortices due to nonlinear twisting of the perturbations' fronts, cascading of perturbations into short scales (direct spectral cascade) and collisional or collisionless damping of the perturbations in the short-wave domain. In the inertial range, direct spectral cascade occurs through merging structures via collisions. It is shown that in the magneto-active plasmas, strong turbulence is generally anisotropic Turbulent modes mainly develop in the direction perpendicular to the local magnetic field. It is found that it is the compressibility of the local medium which primarily determines the character of the turbulent spectra: the strong vortex turbulence forms a power spectrum in wave number space. For example, a new spectrum of turbulent fluctuations in k−8/3 is derived which agrees with available experimental data. Within the framework of the developed model particle diffusion processes are also investigated. It is found that the interaction of structures with each other and particles causes anomalous diffusion in the medium. The effective coefficient of diffusion has a square root dependence on the stationary level of noise

NEW FEATURES OF THE WEATHER FORMING THREE-DIMENSIONAL ULF ELECTROMAGNETIC WAVES IN THE IONOSPHERE

Abstract In the present article the results of theoretical investigation of the dynamics of generation and propagation of planetary (with wavelength 10<sup>3</sup>km and more) three -dimensional weather-forming ultra-low frequency (ULF) electromagnetic waves in the ionosphere are given. It is established, that the global factor, acting permanently in the ionosphere -spatial inhomogeneity and curvature of the geomagnetic field and inhomogeneity of angular velocity of the earth's rotation -generates the fast and slow planetary ULF electromagnetic waves. The waves propagate along the parallels to the east as well as to the west. In E-region the fast waves have phase velocities (2÷20) km/s and frequencies (10<sub>-1</sub> -10<sub>-4</sub>) Hz; the slow waves propagate with local winds velocities and have frequencies (10<sub>-4</sub> -10<sub>-6</sub>) Hz. In F-region the fast ULF electromagnetic waves propagate with phase velocities 10 5 ÷ km/s and their frequencies are in the range of (10 -10<sub>-3</sub>)Hz. The large-scale waves are weakly damped. The waves generate the geomagnetic field from several tens to several hundreds nT and more

On the new modes of planetary-scale electromagnetic waves in the ionosphere

Using an analogy method the frequencies of new modes of the electromagnetic planetary-scale waves (with a wavelength of 10<sup>3</sup> km or more), having a weather forming nature, are found at different ionospheric altitudes. This method gives the possibility to determine spectra of ionospheric electromagnetic perturbations directly from the dynamic equations without solving the general dispersion equation. It is shown that the permanently acting factor-latitude variation of the geomagnetic field generates fast and slow weakly damping planetary electromagnetic waves in both the E- and F-layers of the ionosphere. The waves propagate eastward and westward along the parallels. The fast waves have phase velocities (1–5)km s<sup>–1</sup> and frequencies (10<sup>–1</sup>–10<sup>–4</sup>), and the slow waves propagate with velocities of the local winds with frequencies (10<sup>–4</sup>–10<sup>–6</sup>)s<sup>–1</sup> and are generated in the E-region of the ionosphere. Fast waves having phase velocities (10-1500)km s<sup>–1</sup> and frequencies (1–10<sup>–3</sup>)s<sup>–1</sup> are generated in the F-region of the ionosphere. The waves generate the geomagnetic pulsations of the order of one hundred nanoTesla by magnitude. The properties and parameters of the theoretically studied electromagnetic waves agree with those of large-scale ultra-low frequency perturbations observed experimentally in the ionosphere.<br><Br> <b>Key words.</b> Ionosphere (ionospheric disturbances; waves propagation; ionosphere atmosphere interactions