Concentration of ions in the topside ionosphere as measured onboard the <Emphasis Type="Italic">DEMETER</Emphasis> satellite: Morphology and dependence on solar and geomagnetic activity

Variations in concentration of ions H⁺, He⁺, and O⁺ are studied at a height of about 700 km using the data of continuous observations onboard the DEMETER satellite at the decline and in the minimum of solar activity from 2004 to 2008. Latitudinal distributions, seasonal behavior, and irregular variations in ion concentrations and their dependence on solar and geomagnetic activity are considered. Within this altitude range, for the first time an analysis is performed of the dataset of many-year continuous observations in both hemispheres from the equatorial to subauroral latitudes. This made it possible to describe the seasonal and irregular variations of the concentrations of main ion species with better time and spatial resolution than in the available empirical models. The dependence of concentrations of three types of ions on solar and geomagnetic activity is studied at time scales from several days to several years, and it is shown that the anti-phase change in concentrations of O⁺ and light ions known from publications is partly a result of mutual dependence of solar and geomagnetic activity and is observed only at time scales beginning from several months. At time scales from several days to several weeks, variations in the concentration of O⁺ and light ions are governed mainly by solar and geomagnetic activity, respectively.     

Characteristics of thermal ion outflows in the polar cap according to data of the <Emphasis Type="Italic">Interball-2</Emphasis> satellite

Characteristics of polar wind fluxes at a height of ∼20000 km measured by the Hyperboloid mass-spectrometer installed onboard the Interball-2 satellite are presented in the paper. The characteristics are presented for the upwelling flows of ionospheric ions H⁺, He⁺, and O⁺ from the sunlit polar cap in the period of solar activity minimum. Orbit segments with minimal precipitation of magnetospheric ions and electrons were preliminarily selected, and the measurements where the fluxes of ions coming from the cusp/cleft were excluded as carefully as possible. Thus, the densities, field-aligned velocities, and temperatures of ions in the regions where fluxes of polar wind could be detected with the maximal probability degree are presented in the paper. It is found that cases when only H⁺ ions are reaching the detector are with high probability the polar wind outflows. Their characteristics agree well with the Tube-7 hydrodynamic model and are as follows: n ≈ 1.5 cm⁻³, V _∥ ∼ 21 km/s; T _∥ = 3500 K, and T _⊥ = 2000 K. In cases when He⁺ and O⁺ ions are also detected, the temperatures are substantially higher than the model ones, and the measured field-aligned velocities of O⁺ fluxes are several times higher than the model ones. Moreover, it was revealed that the polar wind outflows are predominantly observed in the polar cap regions where the polar rain fluxes are very small.     

Numerical simulation of effects of the August 11, 1999 solar eclipse in the outer ionosphere

The results of a numerical simulation of such parameters of the topside ionosphere as concentration N _e and temperature T _e of electrons, and concentration n(H⁺) and fluxes along the magnetic field lines Φ(H⁺) of H⁺ ions at an altitude of ～2000 km for the conditions of the August 11, 1999 solar eclipse are presented. The calculations were performed using the Global Self-consistent Model of the Thermosphere, Ionosphere, and Protonosphere of the Earth (GSM TIP). It is shown that during the eclipse, in addition to a region of decreased values of T _e in the Northern Hemisphere and in the magnetically conjugate region in the Southern Hemisphere, regions of electron heating emerge in both hemispheres. Simultaneously, an extended region of decreased values of N _e comes into existence and moves behind the Moon’s shadow. Regions with decreased (down to ～30%) and enhanced (up to ～50%) concentrations of H⁺ ions are detected in the global distribution of these ions.     

variations of the atmospheric chemical composition in the earths’s polar regions after solar proton flare on July 14, 2000 (photochemical simulation)

Altitude—temporal cross-sections q(z, t) of atmospheric ionization rates by solar protons above the polar regions were calculated using the GOES-10 satellite data on solar proton fluxes for the period of solar proton flare (SPF) on July 14, 2000. The values of q(z, t) were used further in calculations of variations of the atmospheric chemical composition during the flare in the northern and southern polar regions (70°N and 70°S) by two different 1D photochemical models of the atmosphere (neutral and charged components). The calculation results have shown considerable variation of the ozone content after SPF: a decrease of [O3] was about 80% at altitudes of 65–75 km above northern and 25% in the layer of 55–65 km above the southern polar region. Such decrease of the ozone content is a result of reactions with [NO] and [OH] whose concentrations have grown substantially during SPF. According to calculations, the increase of electron concentration during SPF has reached 3–4 orders of magnitude at altitudes of 50–80 km. A comparison of the calculation results with the observational data on [NO], [NO2], and [O3] from the UARS and HALOE satellites for 70°N have shown a good qualitative correspondence, however, for variations of nitric oxides there are quantitative discrepancies.     

Radio Occultation Measurements of the Radio Wave Absorption and the Sulfuric Acid Vapor Content in the Atmosphere of Venus

The results of the determination of centimeter ( = 5 cm) radio waves absorption in the radio occultation experiments, carried out using the Venera-15and Venera-16spacecraft, are presented. The altitude distribution of the absorber substance is analyzed. The absorbing layer is shown to exist at altitudes of 64 to 58 km in the near-polar regions of the planet. At middle latitudes such an absorbing layer was not found. In the altitude range from 56 to 46 km the radio wave absorption by the sulfuric acid (H₂SO₄) vapor is observed. The content of the sulfuric acid vapor is shown to increase with decreasing altitude: in the mid-latitude region at altitudes of 56.7 and 53 km it equals 5 and 20 ppm, respectively, and at polar latitudes the same content of H₂SO₄vapor is observed at altitudes of 51.2 and 47 km, respectively. A comparison of these results with the data of radio wave absorption in the = 13 cm band, obtained in the Pioneer Venus Orbiterradio occultation experiments, leads to the conclusion that the obtained values of the sulfuric acid vapor content well agree in the regions of overlap of the data.     

Physicochemical model of the auroral ionosphere

A physicochemical model of excited polar ionosphere has been presented. The model makes it possible to calculate vertical profiles of concentrations of the following excited and ionized constituents: O₂ ⁺, N₂ ⁺, O⁺(⁴S), O⁺(²D), O⁺(²P), O(¹D), O(¹S), N(⁴S), N(²D), N(²P), NO, NO⁺, N⁺, N₂(A³Σ_u ⁺), N₂(B³П_g), N₂(W³Δ_u), and N₂(B′³Σ_u ^-) and the electron concentration during electron precipitations. The energy spectrum of the electrons at the upper boundary of the ionosphere and concentrations of neutral constituents are the input parameters of the model. A model has been compiled based on available publications and includes 56 physicochemical reactions that influence concentrations of the aforementioned constituents in the polar ionosphere. The method of calculating vertical profiles of the excitation rates of atmospheric gases and proper allowance for the electron-vibrational kinetics in the processes of exciting the triplet states of N₂ are specific features of the presented model. The ionospheric model has been approbated using the results of the coordinated rocket–satellite experiment. The agreement between the modeling results and experimental data best for the time being is achieved.     

Characteristics of Near-Polar Atmosphere/Thermosphere of Mars at Altitudes of 125–145 km: The Data of a Radio Occultation Experiment onboard the <Emphasis Type="Italic">Mars Global Surveyor</Emphasis> Spacecraft

Using data from a radio occultation experiment onboard the Mars Global Surveyor spacecraft, altitude variations of the scale height of the neutral atmosphere in the northern and southern hemispheres of Mars are analyzed. The averaged altitude gradient of temperature for neutrals in the thermosphere is estimated. The revealed variations of the scale height of the neutral atmosphere at zenith angles of less than 82° indicate that the near polar atmosphere is not isothermal at altitudes of 125–145 km, which experimentally confirms predictions of models of the Martian atmosphere. It is shown that when one approaches the terminator the near polar atmosphere is cooled and the effects of variation of the solar zenith angle modulate the local time effects in both hemispheres.     

Sources and Losses of Energetic Electrons at Low Altitudes from Satellite Data

Fluxes and differential spectra of 0.04–2.0 MeV electrons at low altitudes in the Earth's magnetosphere are considered in comparison with the model spectra AE-8 MAX and AE-8 MIN. Possible causes of the discrepancy between the observational and model spectra are discussed. The coefficients of radial diffusion at various L-shells are estimated for the maximum of solar activity (using the Interkosmos-19 data) and for the minimum of solar activity (using the Kosmos-1686 data) and are derived from the model AE-8. A quantitative evaluation of the electron yield from radial diffusion at low L shells is derived. Ionization losses, Coulomb angle scattering, and resonant wave–particle interaction are considered as the loss mechanisms. A calculation of these losses at the low L-shells is given. The electron distribution at low L-shells is best fitted by a combination of dissipative terms from different models: Coulomb scattering dominates at the lower L-shells (L = 1.2–1.4) and the resonant wave–particle interaction controls the radiation belt maximum and the gap (L = 1.4–2.0).     

Effects of small-scale plasma disturbance on the IKB-1300 spacecraft potential

The potential of the Intercosmos-Bulgaria-1300 (IKB-1300) satellite launched to a circular orbit at an altitude ～900 km was measured with several instruments. Care was taken to equalize the potential along the satellite surface. The satellite was placed inside the conducting screen and the solar cells had a metal coating. The satellite potential slightly varied along the trajectory and in the typical case it was “?2”B that corresponds to 5 kTe/e. While the satellite crossed the auroral zone small-scale fluctuations of plasma and field parameters, known as shocks, were recorded. In this region a sharp decrease of the satellite negative potential is often observed. In this case the potential variations well correlate with the increasing flux of energetic electrons. The observed variations can be explained by secondary electron emission from the satellite surface.     

Electron flux variations at altitudes of 600–800 km in the second half of 2014. preliminary results of an experiment using RELEC equipment onboard the satellite <Emphasis Type="Italic">VERNOV</Emphasis>

The results of measurements of fluxes and spectra carried out using the RELEC (relativistic electrons) equipment onboard the VERNOV satellite in the second half of 2014 are presented. The VERNOV satellite was launched on July 8, 2014 in a sun-synchronous orbit with an altitude from 640 to 830 km and an inclination of 98.4°. Scientific information from the satellite was first received on July 20, 2014. The comparative analysis of electron fluxes using data from RELEC and using experimental data on the electron detection by satellites Elektro-L (positioned at a geostationary orbit) and Meteor-M no. 2 (positioned at a circular polar orbit at an altitude of about 800 km as the VERNOV satellite) will make it possible to study the spatial distribution pattern of energetic electrons in near-Earth space in more detail.     

Changes in the Earth’s ozonosphere due to ionization of high-latitude atmosphere by solar protons in October, 2003

Using the data of the Russian KORONAS-F satellite and American GOES spacecraft on solar cosmic ray fluxes associated with powerful events which occurred on the Sun at the end of October - the beginning of November, 2003, calculations of ionization of high-latitude (70° N) atmosphere were carried out. The calculations have shown that the maximum values of ionization for the chosen latitude lie in the range of 50–70 km. The largest ionization was caused by the flare on November 28, 2003. Based on a numerical photochemical simulation it is shown that, as a result of intensification of catalytic cycles with participation of ozone-destroying NO and OH, the concentration of ozone decreased by 30% at ionization maximum altitudes.Translated from Kosmicheskie Issledovaniya, Vol. 42, No. 6, 2004, pp. 653–662.Original Russian Text Copyright © 2004 by Krivolutsky, Kuminov, Vyushkova, Kuznetsov, Myagkova.     

Exploration of Venus with the Venera-15 IR Fourier spectrometer and the Venus Express planetary Fourier spectrometer

The infrared spectrometry of Venus in the range 6–45 μm allows one to sound the middle atmosphere of Venus in the altitude range 55–100 km and its cloud layer. This experiment was carried out onboard the Soviet automatic interplanetary Venera-15 station, where the Fourier spectrometer for this spectral range was installed. The measurements have shown that the main component of the cloud layer at all measured latitudes in the northern hemisphere is concentrated sulfuric acid (75–85%). The vertical profiles of temperature and aerosol were reconstructed in a self-consistent manner: the three-dimensional fields of temperature and zonal wind in the altitude range 55–100 km and aerosol at altitudes 55–70 km have been obtained, as well as vertical SO₂ profiles and H₂O concentration in the upper cloud layer. The solar-related waves at isobaric levels in the fields of temperature, zonal wind, and aerosol were investigated. This experiment has shown the efficiency of the method for investigation of the Venusian atmosphere. The Planetary Fourier Spectrometer has the spectral interval 0.9–45 μm and a spectral resolution of 1.8 cm^?1. It will allow one to sound the middle atmosphere (55–100 km) of Venus and its cloud layer on the dayside, as well as the lower atmosphere and the planetary surface on the night side.     

Thermal structure of dayside plasmasphere according to the data of Tail and Auroral Probes, and Magion-5 satellite

We consider the results of measurements of density and temperature of cold plasma in the dayside sector of the plasmasphere. The measurements were made by Interball-1 (Tail Probe) in November 1995, by Interball-2 (Auroral Probe) in August 1996 (the periods close to the solar cycle minimum), and by the Magion-5 satellite in June 2000 (this period is close to the solar cycle maximum). It was shown by the measurements in the dayside sector of the plasmasphere that, contrary to expectations of model distributions of temperature in the plasmasphere [1, 2], under quiet geomagnetic conditions the temperature of hydrogen ions of the cold plasma filling the plasmasphere was observed to increase at altitudes 5000 km < H < 10000 km. Its altitude gradient was equal to ～0.5 deg/km, the geomagnetic latitude being variable within the limits 10° < λ < 40°. The maximum values of temperature of protons, as measured by Tail Probe and Auroral Probe deep in the plasma-sphere, were equal to ～4000–6000 K. According to the data obtained by the Magion-5 satellite in the depth of the plasmasphere, these temperatures varied within the limits 7500–8500 K. These results can be considered as some indication of a dependence of the plasmasphere thermal structure on the phase of the solar cycle. In the region 2.5 < L < 5 and at geomagnetic latitudes λ < 40°, drops of the ion temperature were regularly observed with values reaching ～2000 K.     

红蓝光敏探测器空间环境效应探测数据分析

红蓝光敏太阳电池空间环境效应探测器利用镓铟磷和三结砷化镓太阳电池来探测空间污染、原子氧和辐射环境及效应,搭载在中国空间技术研究院自主研制的“新技术验证一号”卫星上。文章通过分析红蓝光敏探测器在轨1年时间的探测数据,得到如下结论：红蓝光敏探测器污染电池板功率下降2.7%,等效污染累积增加量2.23×10^-5 g/cm^2,日均6×10^-8 g/cm^2;原子氧探测器在轨道高度499.226 km运行11个月,原子氧积分通量探测数据为9.7×10^20 AO/cm^2;辐射效应探测器（三结砷化镓太阳电池）在轨1年后累计接受辐射剂量（等效1 MeV电子注量）5.49×10^11 e/cm^2。     

电动绳系在低极轨卫星中的应用研究

低极轨卫星具有轨道周期短、对地观测分辨率高等优点,但由于所在轨道大气阻力大,其使用寿命受到较大限制。文章提出采用水平结构电动绳系抵消低极轨卫星大气阻力的方法,通过系绳电流与地球磁场相互作用产生洛仑兹力进行推进,进而在无燃料消耗的情况下实现对低极轨卫星轨道高度的维持。初步分析了该方法在低极轨不同尺寸卫星中的应用潜力,计算了160 、400 和800 km 典型高度低极轨卫星所经历的地球磁场、电离层和高层大气环境相关参数变化,比较了不同条件下电动绳系推力与大气阻力大小随轨道位置的变化。分析结果表明,该方法适用于400 km 轨道高度以上大卫星;在满足一定系绳长度和轨道高度的条件下,电动绳系可以有效延长低极轨卫星的轨道寿命。     

Nonlinear Evolution of a Balloon Satellite Orbit

The motion of a spherically symmetric balloon satellite near the equatorial plane is considered. Taking the Earth's oblateness and solar light pressure into account, the integral of motion can be obtained under certain simplifications. The eccentricity is related to the solar angle which represents an angle between pericenter and the Sun. This analytical approximation describes a large and complicated evolution of the eccentricity in corresponding areas of the phase space and the space of parameters. Phase portraits contain fixed saddle points and separatrices that divide different types of oscillations of the eccentricity. In the unsimplified problem, separatrices break down, and specific stochastic motions arise. The aims of the present study are (1) evaluation of the accuracy of analytical approximation with the help of numerical integration using a sufficiently complete model of motion and (2) numerical investigation of stochastic motions and dimensions of stochastic zones in the region of broken separatrices for an adequate model of motion. For a balloon satellite with a semimajor axis of 2.15 Earth's radii and a windage of 30 cm²/g the dimensions of a stochastic zone in eccentricity and solar angle are 10^–5and 0.1°, respectively. The analytical approximation describes the orbit evolution in the right way, except for the cases of large eccentricities, e> 0.4, which corresponds to a pericenter height of less than 1400 km, where the atmospheric drag is already significant.     

Storm deviations of the geomagnetic trap core from dipole configuration deduced from data on relativistic electrons

Satellite data on the position of maximum L _m of the belt of relativistic electrons during strong storms, obtained at low altitudes (∼500 km) and at high altitudes (near the geomagnetic equator plane), are compared (L is the McIlwain parameter). Both at low and high altitudes the maximum of the storm belt of relativistic electrons is formed on the outer edge of the ring current. It is shown that the geomagnetic field can substantially deviate from dipole configuration not only at the geomagnetic trap periphery, but at its core as well (at L ∼ 2.5–3.5), and these deviations are nonlinear. Simultaneous measurements of the fluxes of relativistic electrons at low and high altitudes can serve for estimation of the real shape of magnetic field lines at L < 4 during geomagnetic disturbances.     

Observations of electromagnetic emissions inside the Earth’s plasmasphere from the <Emphasis Type="Italic">Interball-1</Emphasis> satellite

The spectrum analyzer AKR-X onboard the Interball-1 satellite at the beginning (August–October 1995) and at the end (August–October 2000) of satellite operation in perigees of its orbital motion recorded and analyzed electromagnetic emissions of the inner regions of the Earth’s plasmasphere in the frequency band 100–1500 kHz at distances of 1.1–1.8 R _E. The observations have shown that the electromagnetic modes (the Z and LO modes escaping the magnetosphere) which are formed at the altitudes 600–4000 km are associated with the subauroral nonthermal continuum and with the recently discovered kilometric continuum. There are noticeable differences in the spectral character of these emissions during the minimum (1996) and maximum (2000) solar activity, when, as a rule, the LO mode escaping the plasmaphere and the continua are not present.     

Study of notches in the Earth’s plasmasphere based on data of the <Emphasis Type="Italic">MAGION-5</Emphasis> satellite

Depleted narrow (localized in longitude) regions (field tubes) in the plasmasphere, recently discovered in He⁺ radiation measurements on the IMAGE spacecraft, were first directly observed by the Magion-5 satellite. The low-density regions (notches) occupy <～ 10–30° in longitude and extend from L ～ 2–3 to the plasmasphere boundary in neighboring plasmasphere regions with larger densities. The Magion-5 data give evidence that in the low-density regions temperature is enhanced as compared to the neighboring denser plasmasphere regions. Formation of notches in the plasmasphere is, apparently, associated with AE intensification during weak magnetic storms, while strong magnetic storms usually result in the overall reduction of plasmasphere dimensions. However, even a strong magnetic storm on April 6–7, 2000 (max K _p = 9-and min D _st ～ ?290 nT), but accompanied by an isolated AE impulse, resulted in a density decrease only in the longitudinally limited post-midnight sector of the plasmasphere.