V. D. Kuznetsov

Solar and Heliospheric Phenomena in October-November 2003: Causes and Effects

We present new observational data on the phenomena of extremely high activity on the Sun and in the heliosphere that took place in October–November 2003. A large variety of solar and heliospheric parameters give evidence that the interval under consideration is unique over the entire observation time. Based on these data, comparing them with similar situations in the past and using available theoretical concepts, we discuss possible cause-and-effect connections between the processes observed. The paper includes the first results and conclusions derived by the collaboration “Solar Extreme Events-2003” organized in Russia for detailed investigations of these events. As a result of our consideration, it is beyond question that the physical causes of solar and heliospheric phenomena in October–November 2003 are not exclusively local and do not belong only to the active regions and solar atmosphere above them. The energy reservoirs and driving forces of these processes have a more global nature. In general, they are hidden from an observer, since ultimately their sources lie in the subphotospheric layers of the Sun, where changes that are fast and difficult to predict can sometimes take place (and indeed they do). Solar flares can serve as sufficiently good tracers of these sudden changes and reconstructions on the Sun, although one can still find other diagnostic indicators among the parameters of magnetic fields, motions of matter, and emission characteristics.

Controlled injection of high-power radio pulses into the ionosphere-magnetosphere system and appearance of microsubstorms on October 2, 2007

Insignificant geomagnetic disturbances, which originated during the experimental injection of high-power radio pulses into the magnetosphere-ionosphere system with the help of an HF transmitter of the Sura heating facility, are considered. The experiment was performed at 1840–1900 UT on October 2, 2007 (∼2100 MLT) at geomagnetic latitudes close to the zone of generation of the current wedge westward branch, responsible for geomagnetic substorms. The series of two magnetic microsubstorms, with a sudden initial pulse and an insignificant delay relative to the facility switching, was observed at 1840–2000 UT. A disturbance was registered at many stations in the Northern Hemisphere as a global event. The equivalent ionospheric current system of an initial pulse was similar to such a system of the westward auroral surge and had an intensity maximum at Karpogory magnetic observatory, which is the closest station to the Sura facility. Under the conditions of a quiet solar wind and low planetary geomagnetic activity, the AE auroral index correlated with the interplanetary medium parameters (the correlation coefficient reached 0.65) at 1710–2000 UT. It has been confirmed that an initial geomagnetic pulse is generated as a result of radiowave injection. The arguments for and against the generation of microsubstorms due to stimulated precipitation of magnetospheric electrons, as well as the assumption that the geoeffective impact of the interplanetary medium is intensified during the injection of high-power radiowaves near the zone where the westward branch of the current wedge of magnetospheric substorms is generated, are considered.

Auroral activity caused by high-power radioemission from the SURA facility

A series of experimental modifications of the ionosphere in the HF range, performed at the SURA facility base, together with optical measurements onboard the International Space Station (ISS), indicated that such impacts on the ionosphere are effective when the facility operational frequency is higher than the critical plasma frequency (for the main ionospheric F2 layer). The experimental measurements were supported by measurements at ground-based observatories, ISS, and the Demeter and GPS satellites. The analysis results of the entire data set are presented. The ray HF radio tracing for the experiment of October 2, 2007, has been calculated, and it has been indicated that the ionosphere to the north of the facility up to 60°–62° N latitudes was irradiated by the facility beam (the effects of ray redistribution and refocusing) due to refraction on the gradient of the F2 layer critical frequencies. An analysis of the ground-based and satellite measurements (both in the vicinity of a heater and in the magnetically conjugate region) indicates that it is possible to trigger a substorm in experiments with the Sura heating facility.

Ionospheric response to the entry and explosion of the South Ural superbolide

The South Ural meteoroid (February 15, 2013; near the city of Chelyabinsk) is undoubtedly the best documented meteoroid in history. Its passage through the atmosphere has been recorded on videos and photographs, visually by observers, with ground-based infrasound microphones and seismographs, and by satellites in orbit. In this work, the results are presented of an analysis of the transionospheric GPS sounding data collected in the vicinity of the South Ural meteoroid site, which show a weak ionospheric effect. The ionospheric disturbances are found to be asymmetric about the explosion epicenter. The received signals are compared, both in shape and amplitude, with the reported ionospheric effects of ground level explosions with radio diagnostics. It is shown that the confident registration of ionospheric effects as acoustic gravity waves (AGWs) by means of vertical sounding and GPS technologies for ground explosions in the range of 0.26–0.6 kt casts doubt on the existing TNT equivalent estimates (up to 500 kt) for the Chelyabinsk event. The absence of effects in the magnetic field and in the ionosphere far zone at distances of 1500–2000 km from the superbolide explosion epicenter also raises a question about the possibility of an overestimated TNT equivalent. An alternative explanation is to consider the superposition of a cylindrical ballistic wave (due to the hypersonic motion of the meteoroid) with spherical shock waves caused by the multiple time points of fragmentation (multiple explosions) of the superbolide as a resulting source of the AGW impact on ionospheric layers.

Russian Space Program: Experiments in Solar-Terrestrial Physics

We present a brief review of scientific milestones of the Russian Space Research Program for 2006-2015 in the field of solar and solar-terrestrial physics and describe several space projects: CORONAS-PHOTON, RESONANCE, CLIPPER, INTERHELIOPROBE, and

MHD instabilities of collisionless space plasma with heat fluxes

Properties of instabilities in a collisionless plasma are considered based on 16-moment MHD equations with allowance for differences between the heat fluxes along the magnetic field due to longitudinal and transverse thermal ion motions. It is shown that the increments and thresholds appreciably depend on these two heat fluxes for all compressible instabilities arising in the MHD approach (second compressible fire-hose, mirror, and thermal instabilities).

Space projections on solar-terrestrial physics

An overview of the current status of research in the field of solar-terrestrial physics conducted by space agencies of various countries is given. The main results of current (Ulysses, SOHO, TRACE, RHESSI, Hinode, and STEREO) and completed (Coronas-F and others) missions as well as the scientific goals and objectives of space projects being prepared and planned (SDO, Solar Probe, Solar Orbiter, Resonance, Interheliosonde, and others) are presented. The space projects are considered in the context of problems of the Sun—Earth system.

Orbital monitoring of the ionosphere and abnormal phenomena by the small Vulkan-Compass-2 satellite

Natural disasters, the processes of their origin and large-scale technogenic catastrophes are accompanied by anomalous physical phenomena in near-Earth space (NES). In order to reveal such phenomena, record and investigate them, complex NES monitoring is required with the use of specially designed research equipment onboard a low-orbiting spacecraft. This work presents the results of flight tests of the small Vulkan-Compass-2 satellite with research equipment specially designed for orbital monitoring of the ionosphere and search for abnormal phenomena caused by large-scale catastrophes of different nature.

“COMPASS 2” Satellite and Ground-Based Experiments

This review is devoted to modern methods of earthquake (EQ) prediction. Section 4.2 contains the first results of special satellite “COMPASS 2” destined for the detection of seism-electromagnetic (EM) effects. A whistler group in the higher-order guided mode was recorded. Probably it was propagating between two layers, caused by onion-like structure of inhomogeneities in the plasma sphere. In Section 4.3, ELF-VLF effects observed over seism-active regions by the satellite “INTERCOSMOS-24” are considered. It was revealed that the D-region conductivity decreases during the earthquake preparation at Kp < 3 and increases during geomagnetic disturbances. The seismic and geomagnetic effects are assumed to be attributable, respectively, to the increase in near-ground atmospheric conductivity caused by radon emanation during fissuring and to the precipitation of high-energy particles from the inner radiation belt. In Section 4.4, results of the earthquake precursor occurrence time analysis in quasi-static electric field of the surface atmosphere on the Kamchatka Peninsula are presented. The propagation velocity of the precursors and their occurrence time are estimated for different geophysical conditions. ULF-effects in magnetic fields as a result of aftershocks are considered. In Section 4.5, relation between precursors in quasistatic electric fields and in ionosphere parameters is analyzed. This relation reflects the processes of lithosphere–ionosphere interaction.

Effects of the chelyabinsk meteoroid entry at the ionosphere

The transionospheric sounding by signals from the GPS cluster satellites carried out in the zone of explosion of the Chelyabinsk bolid has shown that the explosion had a very weak effect on the ionosphere. The observed ionosphere disturbances were asymmetric with respect to the explosion epicenter. The signals obtained were compared both in shape and in amplitude with the known Earth surface explosions. Ionosphere effects in the form of acoustic-gravity waves (AGW) produced by 260-500 tons TNT explosions on the ground are detected with confidence both by vertical sounding and by GPS techniques. This allows us to suggest that the reported equivalent of the meteoroid explosion was obviously overestimated.