A state-of-the-art review is given of research by computing physics methods on compressible magnetohydrodynamic turbulence in space plasmas. The presence magnetic fields and compressibility this case makes plasma much less amenable to direct numerical simulations than a neutral incompressible fluid. large eddy simulation method discussed, which was developed as an alternative modeling filters the initial equations uses subgrid-scale universal small-scale turbulence. detailed analysis made...

Abstract In this paper, the internal structuring of Polarization Jet (PJ)/Subauroral Ion Drift (SAID) is studied. It shown that PJ/SAID consists several Strata (PJS) electron density and temperature. A new type phenomena has been discovered called Stratified Subauroral (SSAID), which a containing small‐scale PJS. Internal structure SSAIDs measured during various geomagnetic events using data from NorSat‐1, DMSP F‐17 F‐18 satellites. High resolution measurements on Norsat‐1 satellite make it...

We study the spatial structure of a polarization jet/Sub-Auroral Ion Drift (PJ/SAID) based on data from NorSat-1 and Swarm satellites during geomagnetic storm. Observations plasma parameters inside PJ/SAID are obtained with using system Langmuir probes nominal sampling rate up to 1 kHz, which allowed measurements such high temporal resolution for first time. A comparative analysis electron density spectra PJ according both is presented. Our results show that fluctuations increase at all...

In the subauroral zone at boundary of auroral oval in evening and night hours during geomagnetic disturbances, a narrow (about 1°–2°) extended structure (several longitude) is formed. It known as polarization jet (PJ) or ion drift (SAID). The PJ/SAID fast westward one main signatures disturbance ionosphere altitudes F-layer, when AE index reaches more than 500 nT. Plasma speed can reach several kilometres per second, size plasma irregularities inside it scales from tens meters to hundred...

The ERG (Arase) satellite recently discovered a non-thermal hectometric continuum with narrowband frequency structure. mechanism behind the generation of this type emission in near-Earth plasma is still unknown. This study examines potential use electron cyclotron harmonics instability to explain line structure radio emissions for first time. By analyzing case continuum, proposed creation quasi-harmonic resulting quasi-parallel bands discussed. In other words, double resonance effect...

Abstract We report in situ measurements of plasma irregularities associated with a reverse flow event (RFE) the cusp F region ionosphere. The Investigation Cusp Irregularities 3 (ICI‐3) sounding rocket, while flying through RFE, encountered several regions density down to meter scales. address detail most intense small‐scale fluctuations both and AC electric field, which were observed on equatorward edge shear, coincided double‐humped jet fast flow. Due its long‐wavelength low‐frequency...

Abstract The influence of an auroral substorm on the total electron content (TEC) jumps and cycle slips Global Positioning System (GPS) at high-latitudes is studied. For first time, optical data from all-sky imager, as well interplanetary magnetic field magnetometer are used to complete analysis occurrence monitor evolution. Two types considered: (i) instrumental including losses in measured phase GPS signal (ii) sharp TEC variations (TEC jumps) It demonstrated that determined signals mainly...

The large eddy simulation technique is developed for the study of decaying compressible magnetohydrodynamic turbulence. In present paper obtained results numerical computations are compared with direct three-dimensional turbulence under various similarity parameters, namely, magnetic Reynolds numbers, hydrodynamic and Mach numbers. comparison five subgrid-scale closures case made. between carried out regarding time evolution kinetic energy, cross helicity, molecular dissipations turbulent...

Fractal geometry is used to describe the spatial structure of ionospheric conductivity. Topological values fractal dimension and connectivity index, characterizing Pedersen Hall conductivities on nightside auroral zone, are analytically obtained. Restrictions imposed conductivity analyzed in terms percolation currents. It shown that observed scaling for fluctuations electric field glow region well within limitations by critical condition The multiple arc structures corresponds estimates...

Inhomogeneities of plasma density and non-uniform electric fields are compared as possible sources a sort electrostatic ion cyclotron waves that can be identified with broadband extremely low frequency turbulence in the topside auroral ionosphere. Such excited by inhomogeneous energy-density-driven instability. To gain deeper insight generation these waves, computational modeling is performed various parameters. It demonstrated inhomogeneities give rise to this instability even absence...

Abstract In this study, we employ a unique multi‐instrumental approach for comprehensive examination of Polarization Jet (PJ) (or, another name, Subauroral Ion Drift (SAID)). A diverse set data is used to assess the connection between appearance inhomogeneous structure PJ/SAID and its reflection in ground‐based observations during geomagnetic activity. Our combines satellite (Defense Meteorological Satellite Program, NorSat‐1, Swarm) (ionosondes, magnetometers, GPS/GLONASS receivers) data,...

Abstract This work presents the first results of measurements artificial plasma disturbance characteristics using low‐orbit NorSat‐1 satellite, which are excited when ionospheric F2 layer is modified by powerful high‐frequency (HF) waves emitted SURA heating facility. carries multineedle Langmuir probe instrument, capable sampling electron density at a nominal rate up to 1 kHz. The uniqueness this experiment lies in fact that satellite passes very close center HF‐perturbed magnetic flux tube...

In the present article, large eddy simulation (LES) technique for study of compressible magnetohydrodynamic turbulence is developed. The filtered equations magnetohydrodynamics fluid are obtained with use a mass-weighted filtering procedure (Favre filtering). Favre-filtered large-scale components include subgrid-scale terms describing subgrid phenomena. Different models closure suggested. this work numerical and an analysis received characteristics turbulent flow carried out. results...

The excitation of electrostatic turbulence inside space-observed solitary structures is a central topic this exposition. Three representative observed in the topside auroral ionosphere as large-amplitude nonlinear signatures electric field and magnetic-field-aligned current on transverse scales ∼102–103 m are evaluated by theories wave generation inhomogeneous background configurations. A quantitative analysis shows that are, general, effective destabilizing energy-density-driven (IEDD)...

We present the large-eddy simulation method for studying forced compressible magnetohydrodynamic turbulence. The proposed is based on a solution of filtered basic equations magnetohydrodynamics by finite-difference methods and linear representation driving forces in momentum conservation equation magnetic induction equation. These supply production kinetic energies. emphasis placed upon important, not investigated, question about ability approach to reproduce Kolmogorov Iroshnikov–Kraichnan...

Auroral kilometric radiation is used as a tool for the remote diagnostics of processes in Earth’s magnetosphere. Using satellite data and spectrum fluctuations auroral at various frequencies, fractal properties region magnetosphere depending on altitude source frequency generated are studied. The characteristics (Hurst exponent dimension) medium generation their dynamics determined from scaling law. It shown that Hurst increase with (or decrease signal frequency), whereas dimension decreases...

Many electrically and heat conducting fluid flows cannot be described within the framework of incompressible medium or by compressible magnetohydrodynamic equations on assumption polytropic (or adiabatic) process. Therefore, we consider a with use an energy equation. Application large eddy simulation approach to magnetohydrodynamics is considered. The system filtered total equation using mass-weighted filtering procedure has been obtained. It shown that novel subgrid-scale terms arise in...

We present the results of Auroral Kilometric Radiation (AKR) measurements near plasmapause on ERG (Arase) satellite. The apogee satellite's orbit is located ecliptic plane, at latitudes ±30°. According to generally accepted point view, AKR observation impossible in this region since it shielded by plasmasphere. Simultaneous and local plasma density made possible determine that near-equatorial regions occur channels — inhomogeneities elongated along magnetic field lines. from sources auroral...