M.O. Riazantseva

First results of investigating the space environment onboard the Universitetskii-Tatyana satellite

The complex of scientific pay load installed onboard the research and educational Universitetskii-Tatyana microsatellite of Moscow State University is described. The complex is designed to study charged particles in the near-earth space and ultraviolet emissions of the atmosphere. Data of the measurements of charged particle fluxes in the microsatellite orbit are presented, spectra are calculated, and the dynamics of penetration boundaries for protons of solar cosmic rays (SCR) during geomagnetic disturbances in 2005 is investigated. Intensities of the ultraviolet emission are measured in the entire range of variation of the atmospheric irradiation, as well as intensities of auroras in the polar regions of the Northern and Southern hemispheres. The experimental data on flashes of ultraviolet radiation (transient light phenomena in the upper atmosphere) are considered, and some examples of oscillograms of their temporal development and their distribution over geographical coordinates are presented.

Dynamic properties of small scale solar wind plasma fluctuations

The paper presents the latest results of the studies of small-scale fluctuations in a turbulent flow of solar wind (SW) using measurements with extremely high temporal resolution (up to 0.03 s) of the bright monitor of SW (BMSW) plasma spectrometer operating on astrophysical SPECTR-R spacecraft at distances up to 350 000 km from the Earth. The spectra of SW ion flux fluctuations in the range of scales between 0.03 and 100 s are systematically analysed. The difference of slopes in low- and high-frequency parts of spectra and the frequency of the break point between these two characteristic slopes was analysed for different conditions in the SW. The statistical properties of the SW ion flux fluctuations were thoroughly analysed on scales less than 10 s. A high level of intermittency is demonstrated. The extended self-similarity of SW ion flux turbulent flow is constantly observed. The approximation of non-Gaussian probability distribution function of ion flux fluctuations by the Tsallis statistics shows the non-extensive character of SW fluctuations. Statistical characteristics of ion flux fluctuations are compared with the predictions of a log-Poisson model. The log-Poisson parametrization of the structure function scaling has shown that well-defined filament-like plasma structures are, as a rule, observed in the turbulent SW flows.

Enhancements of Fluxes of Precipitating Energetic Electrons on the Boundary of the Outer Radiation Belt of the Earth and Position of the Auroral Oval Boundaries

An analysis of enhancements in the fluxes of electrons with energies above 300 keV registered onboard of the Coronas-F satellite in the polar regions at the boundary of the outer radiation belt is performed. Cases are revealed when the increases in question were observed consequently during multiple crossings of the outer radiation belt boundary. Localization of the revealed events relative to the auroral oval using the data of almost simultaneous observations of electrons with energies of 0.1–10 keV on the Meteor-3M satellite and OVATION model is studied. It is shown that almost all studied increases in relativistic electrons are localized at latitudes of the auroral oval. Various mechanisms which could cause the observed increases are discussed, as well as a possibility of formation of local traps of energetic particles in the high-latitude magnetosphere.

Intermittency of solar wind density fluctuations and its relation to sharp density changes

The paper presents the study of turbulent properties of the solar wind plasma, namely, the intermittency of fluctuations of the solar wind ion flux in the earlier unexplored region of comparatively high frequencies (0.01–1 Hz). Special attention is given to a comparison of intermittency for solar wind observation intervals containing sharp (shorter than 10 min) and high-amplitude (greater than 20%) changes of the ion flux to intervals without such changes. The solar wind observation intervals containing sharp changes of the flux are found to be essentially more intermittent than the intervals of quiet solar wind. Such a comparison allows one to reveal the fundamental difference in turbulent properties of the solar wind depending on the presence or absence of sharp boundaries in plasma structures.

Observation of Fast Variations of the Helium-Ion Abundance in the Solar Wind

This paper describes the results of studying the helium component of the solar-wind ion-flux measurement by the BMSW instrument on the Spektr-R satellite with a time resolution of 3 s. In contrast to most previous works that presented values averaged over large (hourly average or daily average) intervals, we have shown that the relative helium-ion abundance in the solar wind experiences considerable (by a few percent and even 10%) variations on such short intervals as 10 seconds or even several seconds.

Penetration of solar cosmic rays into the Earth’s magnetosphere on January 28, 2012

Results of the comparative analysis of the dynamics of SCR fluxes with energies of 1–100 MeV in the interplanetary environment according to the data of the ACE and Wind spacecraft and within the Earth’s magnetosphere according to the data of the GOES-15 and Electro-L satellites in the region of geostationary orbits, and POES-19 and Meteor-M1 in the region of polar caps during two increases in SCR of January 19–31, 2012, are presented. It is shown that the decrease in the efficiency of SCR penetration into the Earth’s magnetosphere in the region of the orbits under study on January 28, 2012, is related to the passage of the Earth’s magnetosphere through the interplanetary environment structure with a quasi-radial interplanetary magnetic field and a small pressure of the solar wind.

Turbulence in the Magnetosheath and the Problem of Plasma Penetration Inside the Magnetosphere

Chapman & Ferraro (1931) introduced the concept of confinement of the Earths magnetic field in a cavity carved in the solar plasma flow. The balance between the Earth’s magnetic field (more accurately between the magnetic pressure at the boundary of the cavity) and the solar wind dynamic pressure was considered as the condition of the formation of the boundary of the cavity. Chapman-Ferraro model is called a closed magnetosphere. Low energy particles can not penetrate through the boundary of the cavity. Dungey (1961) made the most drastic revision of Chapman-Ferraros original theory. Dungey envisaged that the connection process, called reconnection, takes place on the dayside magnetopause and that the connected field lines are then transported in the antisolar direction by the solar wind, resulting in the magnetotail. Subsequently, the field lines are reconnected there and then transported back to the dayside magnetosphere. Such process takes place when interplanetary magnetic field (IMF) has the southward direction. The large scale reconnection takes place at high latitudes when IMF has the northward direction. The scheme shown on Fig. 1 demonstrates Dungey’s concept of reconnection at the dayside magnetopause when IMF has southword (a) and northward (b) directions. The model of Dungey qualitatively accounts for such phenomena as the inward motion of the dayside magnetopause, equatorward motion of the cusp, expansion of the auroral oval, increase in magnetotail magnetic field strength, and expansion of the magnetotail radius which occur when the IMF turns southward. It can also easily explain the penetration of the plasma of solar wind origin inside the magnetosphere. That is why this concept for a long period was the dominant concept in the physics of the magnetosphere and was widely used for the description of different phenomena including the formation of boundary layers (see, for example, the review Lavraud et al. (2011)). However step by step a number of observations ant theoretical arguments have appeared which give the possibility to throw doubts on the applicability of the scheme shown on Fig. 1 for the real situation.

Hot plasma pressure variations on the geostationary orbit on the base of Gorizont satellite data

Abstract Plasma and energetic particles pressure distribution is studied using data from the plasma and energetic particle experiment (0.1 – 133 keV) onboard the Gorizont-35 geostationary satellite for the period from 11 to 25 March 1992. The analysed period consists of relatively quiet time, small geomagnetic storms, SC and the time of the northern orientation of the IMF. The calculations show that the basic contribution to the total particle pressure was made by ions at the energy from 0.1 to 12.4 keV. The derived average value of the calculated pressure (∼1 nPa) points to the important role of the geostationary orbit plasma population in the formation of the magnetosphere pressure balance and of the near-Earth magnetic field distortion.

Geostationary orbit plasma pressure variations according to gorizont satellite data

Abstract Plasma and energetic particles pressure distribution is studied using data from the plasma and energetic particle experiment (0.1 –133 keV) onboard the Gorizont-35 geostationary satellite for the period from 11 to 25 March 1992. The analysed period consists of relatively quiet time, small geomagnetic storms, SC and the time of the northern orientation of the IMF. The calculations show that the basic contribution to the total particle pressure was made by ions at the energy from 0.1 to 12.4 keV. The derived average value of the calculated pressure (≈1 nPa) points to the important role of the geostationary orbit plasma population in the formation of the magnetopause pressure balance and of the near-Earth magnetic field distortion.

Solar-wind structure propagation through the magnetosheath studied by two Themis probes

The penetration and transformation of solar-wind plasma structures at propagation through the turbulent magnetosheath were studied over time intervals from a few seconds to a few minutes using data of plasma density measurements on two closely located satellites of the Themis mission. It was shown that near Earth bow shock and the magnetosheath have added high-frequency fluctuations with frequencies higher than 0.01–0.02 Hz to initial variations of solar wind’s plasma density. As a result of the analysis of several long intervals, it was found that the correlation coefficient can undergo drastic changes, while decreasing from large to rather small values for several minutes and then increasing again. Factors affecting the level of correlation between the solar wind’s plasma density and the magnetosheath were studied statistically. It was shown that a high level of correlation is observed, in a large percentage of cases, at high values of the interplanetary magnetic field magnitude, the plasma density and the magnitude of solar wind’s directed velocity. The level of correlation also considerably grows with increasing amplitude of solar-wind plasma structures.