Outer Ionosphere Research Articles

Influence of the Outer Ionosphere on the Magnetic Field of a Controlled Source in the 0.4–10 Hz Frequency Range

Influence of the Outer Ionosphere on the Magnetic Field of a Controlled Source in the 0.4–10 Hz Frequency Range

Structure of the Martian Dayside Magnetosphere: Two Types

A set of scientific instruments capable of high temporal resolution measurements onboard the Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft made it possible to study the structure and properties of the dayside Martian magnetosphere. The Mars plasma envelope on the dayside of the planet was discovered based on observations on the first orbiters of Mars (Vaisberg et al., 1976; Gringauz et al., 1976). The high temporal and mass resolution of MAVEN instruments made it possible to study the structure and processes in the plasma of the dayside magnetosphere, the plasma layer that exists between the solar wind heated by the shock wave and the ionosphere (Vaisberg et al., 2017). It is shown that, under different external conditions, two different types of plasma layers are formed between the ionosphere and magnetosheath on the dayside of the planet: (1) mixture of heated ionospheric ions and picked-up exospheric ions and (2) a layer of ionospheric ions accelerated by the solar wind motional electric field called “plume” (Dong et al., 2015). The first type of the Martian daytime magnetosphere is formed as a result of the interaction of oxygen exospheric ions captured and accelerated by the solar wind with the upper part of the Martian ionosphere (Vaisberg and Shuvalov, 2021). The second type of the Martian dayside magnetosphere is formed by the acceleration of an ion beam from the outer ionosphere, which then passes into a more energetic plume beam in the magnetosheath. This article discusses typical plasma populations, their properties and conditions that lead to the formation of the daytime magnetosphere from the material of the upper ionosphere.

Features of generation and propagation of the extremely low frequency waves excited in the ionosphere under the powerful HF radioemission influence

The experimental results of the extremely low frequency emission characteristics excited in the outer ionosphere under the ionospheric plasma heating by high-latitude EISCAT facility are presented. The experiments have been conducted in the period of 20062010 yr. using two main schemes of extremely low frequency generation including the impact of the heating facility amplitude modulated emission and two unmodulated pump waves with the frequency detuning. In-situ measurements of the plasma wave disturbances were performed at the outer ionosphere heights using on-board equipment of DEMETER microsatellite. In work the spatial, amplitude and spectral characteristics of the generated extremely low frequency emissions are determined. It is shown that the characteristic size of the extremely low frequency emission is about 400600 km along the trajectory of the DEMETER microsatellite. The registration area spatial position is determined by both the applied generation scheme and the background plasma density distribution. The extremely low frequency emission electric field strength at the Earths outer ionosphere heights is 50330 V/m.

Role of the Outer Ionosphere in the Winter/Summer Asymmetry of Auroral Electron Precipitations

This paper analyzes the role of the outer ionosphere in the occurrence of a large difference in the frequency of accelerated electron fluxes in the auroral region in the premidnight sector for winter and summer conditions, which are associated with discrete auroras. Simulation indicates that the critical value JEIC of the longitudinal current of the Alfven wave for the development of electrostatic ion–cyclotron instability at heights around the Earth’s radius (h ~ RE) for winter almost coincides with the upper limit of average values of the stationary large-scale longitudinal current. Therefore, weak fluctuations of the longitudinal current associated with the Alfven wave are sufficient in winter for the development of processes leading to accelerated electron fluxes, which are associated with discrete auroras. The summer value of JEIC is four to five times higher than that for winter, and a stimulated precipitation of auroral electrons is likely to be possible only at high geomagnetic activity. The winter/summer asymmetry in the JEIC value is mainly associated with specific changes in the parameters of the outer ionosphere along the geomagnetic field. The difference in electron density reaches a maximum at heights h ~ RE, where the summer values of this density are five to six times higher than the winter ones, which, in turn, is associated with higher summer temperatures of electrons and ions. The important role of these temperatures in the winter/summer asymmetry in the frequency of accelerated electrons has been noted, it would seem, for the first time.

Assessment of the Accuracy of Calculations Using the International Reference Ionosphere Model IRI-2016: I. Electron Densities

The paper quantitatively compares the results of calculations of the electron density Ne by the International Reference Ionosphere model IRI-2016 with experimental data obtained from the DE-2 satellite. It considers 648 variants of heliogeophysical conditions. The deviation of theoretical estimates from experimental values is within the instrumental accuracy of satellite data in an average of 27% of cases. It is concluded that the IRI-2016 model, the approximation coefficients of which in functional dependences are associated with heights of the F-region, gives negative values of the efficiency coefficient of the predicted electron density in ~73% of cases in the outer ionosphere at altitudes over 500 km.

Determination of the Ion Composition of the Outer Ionosphere from the Characteristics of ELF–VLF Waves Detected during the Operation of the Sura Facility

The propagation characteristics and physical nature of low-frequency waves observed in the ionosphere during heating of the near-Earth plasma by a powerful short-wavelength radiation are investigated using the singular value decomposition method. The experimental results obtained with the Sura midlatitude heating facility and detected by the onboard equipment of the DEMETER satellite were used. The ion composition of the near-Earth plasma is estimated from the spectral characteristics of the observed radio waves. The method is verified using results of full-scale measurements performed at altitudes corresponding to the Earth’s outer ionosphere.

Ground-Based Measurements of the Outer-Ionosphere Turbulence Induced by a High-Power VLF Transmitter

We present experimental results on the detection of artificial irregularities produced in the ionospheric plasma by a high-power VLF transmitter. The analysis of TEC variations and ionosonde data was used for the diagnostics of ionospheric turbulence. Spatial distribution of the electric field amplitude of the VLF transmitter was calculated for selection of the NAVSTAR and GPS satellites the signal from which passes through the perturbed region. A quite different TEC variation curve was observed in the reference measurement when the transmitter was out of operation. Operation of the VLF transmitter resulted in the appearance of F spread in the ionosonde data (the effect took place at night). The experiment showed for the first time that with the help of ground-based measurements of TEC it is possible to study the region of turbulence in the outer ionosphere induced by the operation of a VLF radio station.

The Results of Measurements of Features of Artificial Electromagnetic and Plasma Perturbations in the Outer Ionosphere of the Earth Using the DEMETER Satellite

The results of the DEMETER satellite mission for 2005–2010 are summarized. The characteristics of electromagnetic and plasma perturbations induced in the F2 layer of the Earth’s ionosphere by the highpower HF radio waves from the SURA heating facility are analyzed.

Transionospheric radiosounding (Review)

The transionospheric radiosounding (TIS) method has naturally brought together the two most precise methods for scanning and monitoring the ionosphere (ionospheric radiosounding by airborne and ground ionosondes) into a single system. The subsequent development of TIS equipment has led to a qualitative change in the structure and operation of the ionospheric observatory, which greatly broadened the diagnostic capabilities of the ionospheric monitoring and expanded the ionospheric region monitored by the ground station. In fact, it can be said that a closed radiosounding system has been developed. It uses three branches of ionospheric multifrequency ray (or radio wave) fans to monitor the inner and outer ionosphere and to control both of these regions via transillumination of the ionosphere at the boundary of its radio transparency. The advantage of such a system is the full use of the entire range of radiated radio waves, each part of which is responsible for certain components of the diagnostic circuit. The paper presents the results of scientific studies obtained based on TIS data, which have led to the appearance of new and, to some extent, unexpected and previously unknown phenomena and effects. Special attention is paid to the modern stage of development of the TIS concept, which has good prospects for continuous monitoring of the polar ionosphere. It is questioned whether it is expedient to replace the term sounding with the term transillumination. It is noted that TIS was and remains the most precise method of ionosphere diagnostics.

Features of the Electromagnetic and Plasma Disturbances Induced at the Altitudes of the Earth’s Outer Ionosphere by Modification of the Ionospheric F 2 Region Using High-Power Radio Waves Radiated by the SURA Heating Facility

In this paper we systematize the results of studying the characteristics of the plasma-density ducts, which was conducted in 2005–2010 during the DEMETER-satellite operation. The ducts are formed at altitudes of about 700 km as a result of the ionospheric F 2 region modification by high-power high-frequency radio waves radiated by the midlatitude SURA heating facility. All the performed measurements are used as the basis for determining the formation conditions for such ducts, the duct characteristics are studied, and the opportunities for the duct influence on the ionosphere–magnetosphere coupling and propagation of radio waves of various frequency ranges are demonstrated. The results of numerical simulation of the formation of such ducts are presented.

ВАРИАЦИИ ПЛАЗМЕННЫХ ТЕМПЕРАТУР В ИОНОСФЕРЕ НАД ХАРЬКОВОМ В ТЕЧЕНИЕ ГЛУБОКОГО МИНИМУМА СОЛНЕЧНОЙ АКТИВНОСТИ

PACS numbers: 93.30.Ge, 94.20.Cf, 94.20.Dm, 94.20.Fg Purpose: to present temperature variations of electrons and ions obtained at the Institute of Ionosphere (Kharkiv) with an incoherent scatter radar during the 23rd solar cycle minimum, and compare the obtained results with the corresponding data of IRI-2012 model. Design/methodology/approach : Data are obtained by incoherent scattering. Method of solving the inverse radiophysics problem was used for analysis. Two-dimensional ambiguity function was used for specification. Findings: It has been found that in most cases the IRI-2012 model overestimates the values of electron and ion temperatures as against experimental data. The maximum differences are observed at night and can be about 500 K in summer, and 700 K in winter. Also, the effects of sunrise and sunset in magnetoconjugate area are considered. Conclusions: It is confirmed that to adequately describe processes in the ionosphere it is necessary to have a systematic approach which takes into account interaction in ionospheric regions located in magneto-conjugate area. Such regularities must be taken into account for correction of ionospheric model for the Central European region. Key words: method of incoherent scattering, electron temperature, ion temperature, magneto-conjugate area Manuscript submitted: 22.02.2016 Radio phys. radio astron. 2016, 21(2): 132-140 REFERENCES 1. CHERNOGOR, L. F., 2006. Earth–atmosphere–ionosphere–magnetosphere as an open dynamic nonlinear physical system (Part 1). Nelinejnyj mir. vol. 4, no. 12, pp. 655–697 (in Russian). 2. CHERNOGOR, L. F., 2007. Earth–atmosphere–ionosphere–magnetosphere as an open dynamic nonlinear physical system (Part 2). Nelinejnyj mir. vol. 5, no. 4, pp. 198–231 (in Russian). 3. EVANS, J. V., 1969. Theory and Practice of Ionospheric Study by Thomson Scatter Radar. Proc. 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V., EMMERT, J. T. and QIAN, L., 2010. Anomalously low solar extreme ultraviolet irradiance and thermospheric density during solar minimum. Geophys. Res. Lett. vol. 37, id. L16103. DOI: https://doi.org/10.1029/2010GL044468 9. TARAN, V. I., 2001. Study of the ionosphere in the natural and artificially excited states dy method of incoherent scattering. Geomagnetizm i aeronomija. vol. 41, no. 5, pp. 659–666 (in Russian). 10. DOMNIN, I. F., KOTOV, D. V. and CHERNOGOR, L. F., 2012. Optimization of the ionospheric plasma parameters estimation using the incoherent scatter technique. Nelineinyi mir. vol. 10, no. 6, pp. 380–386 (in Russian). 11. SIUSIUK, M. N., KOTOV, D. V. and BOGOMAZ, A. V., 2011. Modeling two-dimensional uncertainty function in incoherent scatter radar. Vestnik Natsionalnogo tekhnicheskogo universiteta. no. 44, pp. 81–84 (in Russian). 12. TRUHLIK, V., BILITZA, D. and TRISKOVA, L, 2012. A new global empirical model of the electron temperature with the inclusion of the solar activity variations for IRI. Earth Planets Space. vol. 64, pp. 531–543. DOI: https://doi.org/10.5047/eps.2011.10.016 13. APONTE, N., BRUM, CH. G. M., SULZER, M. P. and GONZALEZ, S. A., 2013. Measurements of the O+ to H+ transition height and ion temperatures in the lower topside ionosphere over Arecibo for equinox conditions during the 2008–2009 extreme solar minimum. J. Geophys. Res. Space Phys. vol. 118, pp. 4465–4470. DOI: https://doi.org/10.1002/jgra.50416 14. PICONE, J. M., HEDIN, A. E. and DROB, D. P., 2002. NRLMSISE-00 empirical model of the atmosphere: Statistical comparisons and scientific issues. J. Geophys. Res. Space Phys. vol. 107, no. A12, id. 1468. DOI: 0.1029/2009JA009430 15. CARLSON, H. C., 1966. Ionospheric Heating by Magnetic Conjugate-Point Photoelectron. J. Geophys. Res. Space Phys. vol. 71, no. 1, pp. 195–199. DOI: 10.1029/JZ07li001p00195 16. KAKINAMI, Y., BALAN, N., LIU, J. 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Investigation of the spatial structure and developmental dynamics of near-Earth plasma perturbations under the action of powerful HF radio waves

Results of numerical simulations of the near-Earth plasma perturbations induced by powerful HF radio waves from the SURA heating facility are presented. The simulations were performed using a modified version of the SAMI2 ionospheric model for the input parameters corresponding to the series of in-situ SURA–DEMETER experiments. The spatial structure and developmental dynamics of large-scale plasma temperature and density perturbations have been investigated. The characteristic formation and relaxation times of the induced large-scale plasma perturbations at the altitudes of the Earth’s outer ionosphere have been determined.

Structure of the Electric Field of a High-Power Radio Wave in the Outer Ionosphere

The electric field of a high-power HF radio wave radiated by the Sura facility was measured using onboard instruments of the French microsatellite DEMETER at altitudes of 670 km. The data analysis shows that the high-power radio wave passes to the outer ionosphere under conditions where the difference between the cutoff frequency and the pump-wave frequency does not exceed 0.5–0.7 MHz in the undisturbed ionosphere. Energy and spatial characteristics of the high-power radio wave transmitted through the ionosphere are determined. A possible mechanism explaining such a penetration to the supercritical plasma is discussed.

Electric field variability and classifications of Titan's magnetoplasma environment

Abstract. The atmosphere of Saturn's largest moon Titan is driven by photochemistry, charged particle precipitation from Saturn's upstream magnetosphere, and presumably by the diffusion of the magnetospheric field into the outer ionosphere, amongst other processes. Ion pickup, controlled by the upstream convection electric field, plays a role in the loss of this atmosphere. The interaction of Titan with Saturn's magnetosphere results in the formation of a flow-induced magnetosphere. The upstream magnetoplasma environment of Titan is a complex and highly variable system and significant quasi-periodic modulations of the plasma in this region of Saturn's magnetosphere have been reported. In this paper we quantitatively investigate the effect of these quasi-periodic modulations on the convection electric field at Titan. We show that the electric field can be significantly perturbed away from the nominal radial orientation inferred from Voyager 1 observations, and demonstrate that upstream categorisation schemes must be used with care when undertaking quantitative studies of Titan's magnetospheric interaction, particularly where assumptions regarding the orientation of the convection electric field are made.

Characteristics Analysis for the Spherical Antenna of a Seismometer

A seismometer for vertical electric field component of natural ELF and ULF electromagnetic waves measurement by using spherical antenna is introduced. The goal of the proposed seismometer is to provide continuous observation of the natural electromagnetic emissions related to the coupling of seismic activity with the outer spaces and ionosphere, which utilize a spherical aluminum electrode 78mm in diameter with embedded enhanced preamplifier circuits that built to mount flush with the ground so as to preserve the configuration in which the antenna operates. The presented seismometer has a wide frequency response at low frequencies, it's typical sensitivity in the frequency range DC to 30MHz are shown to be and ,the dynamical range is >50dB in ELF and VLF and about 25dB in HF.

Построение профиля электронной концентрации по его геометрическим параметрам при моделировании области F2 и внешней части ионосферы

Построение профиля электронной концентрации по его геометрическим параметрам при моделировании области F2 и внешней части ионосферы

Low-frequency noise at altitudes of the outer ionosphere and solar activity

The results of recording the intensity of low-frequency electromagnetic emissions at altitudes of the outer ionosphere based on satellite data at various levels of solar activity have been investigated. The intensity of low-frequency emissions has been found to depend on the solar activity, i.e., the spatial noise characteristics vary. Mean values of the noise amplitude variations at various phases of the solar activity cycle are presented. The low-frequency emissions are shown to serve as a source of information about the processes in the surface plasma; in particular, the state of the radiation belts is judged from them. The noise carries information about the variations in the particle fluxes intruding into the Earth’s plasmasphere under various solar activity conditions and about the magnetospheric plasma variations related to the growth of solar activity. In other words, the electromagnetic low-frequency noise can be a peculiar kind of indicator of the solar activity and the state of the magnetosphere.

Electromagnetic and plasma perturbations induced by radio emission of the EISCAT high-frequency heating facility in the outer ionosphere of the earth

We present the results of measuring the characteristics of electromagnetic and plasma perturbations at the altitudes of the Earth’s outer ionosphere, which were obtained by the onboard equipment of the French microsatellite DEMETER when it passed through the magnetic flux tube based on a region modified by high-power HF radio emission of the EISCAT heating facility. Physical mechanisms which allow one to explain the observed phenomena are considered.

Density ducts formed by heating the Earth’s ionosphere with high-power HF radio waves

The parameters of plasma disturbances at altitudes 660 and 840 km, measured by the instruments onboard the French DEMETER satellite and the US DMSP satellites passing through the magnetic flux tube footed at the region of intense modification of the F2 ionospheric layer by the high-power HF radio waves of the Sura heating facility, are presented. The formation of artificial enhanced-density plasma ducts in the outer ionosphere is observed experimentally. Conditions facilitating the formation of such ducts are pointed out.

Some results of measuring the characteristics of electromagnetic and plasma disturbances stimulated in the outer ionosphere by high-power high-frequency radio emission from the “Sura” facility

We present the results of measuring the characteristics of electromagnetic and plasma disturbances at altitudes of about 700 km, obtained by using the onboard equipment of the French microsatellite DEMETER during its passage through the magnetic tube resting upon the region of intense generation of artificial ionospheric turbulence created due to modification of the ionospheric F2 region by high-power radio emission from the “Sura” facility. It is shown that an artificial density duct emerging from the disturbed region and extending to the Earth’s magnetosphere can be formed.