E. N. Sosnovets

Magnetic storms in October 2003

Preliminary results of an analysis of satellite and ground-based measurements during extremely strong magnetic storms at the end of October 2003 are presented, including some numerical modeling. The geosynchronous satellites Ekspress-A2and Ekspress-A3, and the low-altitude polar satellites Coronas-F and Meteor-3M carried out measurements of charged particles (electrons, protons, and ions) of solar and magnetospheric origin in a wide energy range. Disturbances of the geomagnetic field caused by extremely high activity on the Sun were studied at more than twenty magnetic stations from Lovozero (Murmansk region) to Tixie (Sakha-Yakutia). Unique data on the dynamics of the ionosphere, riometric absorption, geomagnetic pulsations, and aurora observations at mid-latitudes are obtained.

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.

Investigations of the space environment aboard the Universitetsky-Tat’yana and Universitetsky-Tat’yana-2 microsatellites

The first results obtained through the university small satellites program developed at Moscow State University (MSU) are presented. The space environment was investigated aboard two MSU microsatellites designed for scientific and educational purposes, Universitetsky-Tat’yana and Universitetsky-Tat’yana-2. The scientific equipment is described to study charged particles in near Earth space and atmospheric radiations in ultraviolet, red, and infrared optical wavelength ranges. The dynamic properties of fluxes of charged particles in microsatellite orbits are studied and findings are presented regarding specific parameters of solar proton penetration during the geomagnetic disturbances. Experimental results are considered concerning flashes of ultraviolet (UV), red (R), and infrared (IR) radiation that are transient light phenomena in the upper atmosphere. The space educational MSU program developed on the basis of the Universitetsky-Tat’yana projects is reviewed.

A study of long-term strong dawn-dusk asymmetry of the earth's magnetosphere in 1991

Abstract A study of dawn-dusk asymmetry of the Earths magnetosphere was made by the indirect way using data from a middle-energy-range (E: ∼ 80/1000 keV) electron semiconductor spectrometer onboard the geosynchronous satellite Gorizont from July, 1991 to April, 1992. In July-September, 1991 the diurnal variation of the examined fluxes had a number of unusual features. The most interesting feature was existence of local maxima on the diurnal distribution of electron flux intensity in dawn and dusk sectors. Observed features of the flux distributions could be explained as appeared due to the particle drift in the strong dawn-dusk asymmetry of the magnetospheric magnetic field. In the presented case, probably, the intrinsic factor was the main cause stabilising the dawn-dusk asymmetric geomagnetic field.

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.

Diurnal variations of ion flux intensity on a synchronous orbit

Abstract The data from the synchronous-orbit satellites of the Gorizont series are used to study the dependences of the ion flux variation amplitudes in the synchronous altitude region (the diurnal behaviour) on particle energies and on the form and rigidity of the particle energy spectrum. The proton fluxes were measured in the energy range E ∼ 60–120 keV, and the [N,0] 2+ and [C,N,0] 4+ ion fluxes in the energy range E ∼ 60–70 keV/e. The ratio of the diurnal variation amplitudes of the studied ions is shown to correspond to the similarity of their energy spectra in the E/Q representation. The magnetically-quiet time gradient of the distribution function F(μ,J,L) in the synchronous-orbit region is shown to be (∂F/∂L)=0 for the H + and [N,0] 2+ ions and (∂F/∂L) > 0 for the [C,N,0] 4+ ions (at the values of μ corresponding to the examined energy ranges). During magnetically-disturbed periods the inner boundary of the (∂F/∂L)=0 region shifts to lower L and (∂ F/∂L) = O in the synchronous altitude region must be also for the [C,N,O] 4+ ions.

Detection and prediction of absorbed radiation doses from solar proton fluxes onboard orbital stations

We consider cases of simultaneous detection of the absorbed doses produced by proton fluxes of powerful solar events onboard the Mir and ISS orbital stations and the Ekspress A3 geosynchronous satellite. Experimental data are analyzed using a software package that takes into account the energy spectra of protons at the Earths orbit depending on the time of event evolution, as well as their penetration to near-earth orbits and through the protective shields of spacecraft. Based on a comparison of the experimental data of dosimeters with the calculation of absorbed doses under the action of solar proton events, we developed a method of estimating the effective thickness of the shielding of dosimeters and made some estimates. A possibility is considered for predicting the radiation hazard onboard orbital stations upon the appearance of solar proton events using dosimeter data from a geosynchronous orbit.

Observation of the Near Plasma Sheet, Ring Current, and Energetic Electrons from Radiation Belts at a Geosynchronous Orbit, March 11–25, 1992

The dynamics of near plasma sheet electrons and ions (E≈ 0.1–12.4 keV), ring current protons (Ei≈ 41–133 keV), and energetic electrons from the Earths radiation belts (Ee≈ 97–1010 keV) is considered using the data from the Gorizont-34and Gorizont-35geosynchronous satellites from March 11–25, 1992. Peculiarities of this period are a long (more than 4 days) interval of the northward interplanetary magnetic field (Bz> 0) and a high-speed stream of the solar wind with an enhanced particle density. The SC and compression of the magnetosphere to the geosynchronous orbit (GMC) preceded this interval. Under quiet and moderately disturbed geomagnetic conditions and under a prolonged northward interplanetary magnetic field, we observed a significant decrease of fluxes and softening of spectra of the electron component of plasma in the energy ranges of 0.1–12.4 keV and 97–1010 keV, and of the ion component of plasma at energies of 0.1–4 keV, while the intensity of 5–12.4 keV ion fluxes increases by about one order of magnitude. The peculiarities of distributions of energetic particle fluxes observed in the period under consideration can be associated with significant variations of the convection conditions and a decreased or fully suppressed injection of energetic electrons into the geosynchronous orbit region.

Dynamics and ions composition of the ring current during substorms: the Gorizont‐35 results

The geosynchronous satellite Gorizont‐35 observations and analysis of the ring current H+ (protons), He2+ (α‐particles) and O+ ions energy spectra variations near noon (11.30±01.30 LT) and midnight (23.30±01.30 LT) during substorms and storms (11–25 March 1992) are presented. Measurements were made in the energy range E=41–133 keV/e in seven channels (ΔE/E≊0.1). It has been discovered that the O+ ions are the main component of the ring current energy density during the period of the active Sun. The He2+ ions are the most dynamic component of the ring current (especially for E<70 keV/e). At midnight the H+, He2+ and O+ ions energy spectra are similar to the same energy per charge presentation form. The obtained data are compared with the AMPTE/CCE(CHEM) results. Formation of the space and energy features mentioned above and variations of ring current ions composition physical processes are discussed.