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  • 1
    Electronic Resource
    Electronic Resource
    Simultaneous measurements from the Millstone Hill radar and the Active satellite during the SAID/SAR arc event of the March 1990 CEDAR storm (1999)
    Springer
    Annales geophysicae 17 (1999), S. 389-404 
    Details
    ISSN: 0992-7689
    Keywords: Ionosphere (ionosphere-magnetosphere interactions; plasma temperature and density) ; Magnetospheric physics (plasmasphere)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract During a nearby passage of the Active satellite above the Millstone Hill radar on 21 March 1990 at local sunset, the satellite and the radar performed simultaneous measurements of upper ionospheric parameters in nearly the same spatial volume. For this purpose the radar carried out a special azimuth-elevation scan to track the satellite. Direct comparisons of radar data and in situ satellite measurements have been carried out quite rarely. In this case, the coincidence of co-ordinated measurements and active ionospheric-magnetospheric processes during an extended storm recovery phase presents a unique occasion resulting in a very valuable data set. The measurements show generally good agreement both during quiet prestorm and storm conditions and the combination of radar and satellite observations gives a more comprehensive picture of the physical processes involved. We find a close relationship between the rapid westward ion drift peak at subauroral latitudes (SAID event) and the occurrence of a stable auroral red (SAR) arc observed after sunset by an all-sky imager and reported in an earlier study of this event. The SAID electric field is caused by the penetration of energetic ions with energies between about 1 keV and 100 keV into the outer plasmasphere to a latitude equatorward of the extent of the plasmasheet electrons. Charge separation results in the observed polarisation field and the SAID. Unusually high molecular ion densities measured by the satellite at altitudes of 700–870 km at subauroral and auroral latitudes point on strong upward-directed ion acceleration processes and an intense neutral gas upwelling. These structures are collocated with a narrow trough in electron density and an electron temperature peak as observed simultaneously by the radar and the satellite probes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s00585-999-0389-6
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  • 2
    Electronic Resource
    Electronic Resource
    On the periodic variations of secondary cosmic rays and the geomagnetic Pc4 pulsations in BMAr (1997)
    Springer
    Annales geophysicae 15 (1997), S. 1009-1014 
    Details
    ISSN: 0992-7689
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract In a set of balloon flights in the Brazilian magnetic anomaly region (BMAr) short time periodic variations were observed, i.e. pulsation, of secondary charged and neutral particle fluxes, X- and γ-ray fluxes with amplitudes of about 2–4%. The pulsations are accompanied by the geomagnetic Pc4 pulsations and have similar periodicity. The phenomenon was observed over various local times and in quiet and disturbed magnetospheric conditions. One of the explanations of this effect, i.e. periodic variation of local cut-off rigidity, and following pulsations of primary and secondary cosmic ray intensity is suggested.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s00585-997-1009-y
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  • 3
    Electronic Resource
    Electronic Resource
    On the oxidation of silicon in a microwave discharge (1971)
    Springer
    Czechoslovak journal of physics 21 (1971), S. 1016-1018 
    Details
    ISSN: 1572-9486
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01706497
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  • 4
    Electronic Resource
    Electronic Resource
    Connections between neutron monitor count rate and solar modulation strength (1999)
    Springer
    Czechoslovak journal of physics 49 (1999), S. 1743-1749 
    Details
    ISSN: 1572-9486
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We suggest a new approach to the normalisation of neutron monitor response to galactic cosmic rays. The reference normalisation count rate is the neutron monitor response to the model unmodulated flux of galactic cosmic rays. A comparison of the actually recorded neutron monitor count rate with the calculated normalisation count rate can provide one with an observationally obtained true-of-date integral measure of the current level of solar modulation of galactic cosmic rays.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022888121484
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  • 5
    Electronic Resource
    Electronic Resource
    Cosmic-ray modulation and long-duration solar flare events (1994)
    Springer
    Solar physics 154 (1994), S. 371-376 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The correlation between the long-term intensity variations of cosmic rays at neutron monitor energies and the LDE index measure of solar flares with long-lasting soft X-ray emissions is reported. Three subsequent solar cycles, 20–22, are taken into account and half-monthly data are analyzed. Possible explanation of this correlation is discussed in terms of the recent concepts of cosmic-ray modulation, in particular with merged interaction regions affecting the cosmic-ray intensity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00681105
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  • 6
    Electronic Resource
    Electronic Resource
    Characteristics of enhanced and low-amplitude cosmic-ray diurnal variation (1995)
    Springer
    Solar physics 159 (1995), S. 191-202 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The occurrence of a large number of high- and low-amplitude cosmic-ray diurnal wave trains during the two solar cycles (20 and 21) over the years 1965–1990 has been examined as a function of solar activity. The high-amplitude days with the time of maximum in the ∼ 18:00 hr corotation direction do not indicate any significant correlation with solar activity. But, the low-amplitude days are inversely correlated with solar activity and the time of maximum shifts to earlier hours (∼ 15:00 hr direction). The slope of the power-specrum density roughly characterized by power spectral index ‘n’ in the high-frequency range 3.5 x 10−5 Hz to 8.3 x 10−4 Hz (time scales of 20 min to 8 hr) is different for the two classes of events. A suggestion is made that the enhanced and low-amplitude cosmic-ray diurnal variations are produced by different types of interplanetary magnetic field distributions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00733042
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  • 7
    Electronic Resource
    Electronic Resource
    Synchrotron radiation of electrons trapped in earth's magnetosphere (1989)
    Springer
    Czechoslovak journal of physics 39 (1989), S. 1423-1428 
    Details
    ISSN: 1572-9486
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Relatively large fluxes of trapped electrons with energy above several tens of MeV in the inner radiation belt, established according to low altitude satellite measurements, invoked the question of their production of synchrotron radiation in geomagnetic field. Based on experimental data on electrons, rough estimate of the spectral density of synchrotron radiation at the Equator is obtained in the region of maximum emissivity. Relatively low value of the radiation flux implies that only precise measurements at 1 GHz allowing to measure the directivity of emissions may be relevant.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01597607
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  • 8
    Electronic Resource
    Electronic Resource
    Cosmic-ray fluctuations and interplanetary magnetic fields (1993)
    Springer
    Astrophysics and space science 199 (1993), S. 125-132 
    Details
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The relations of cosmic-ray fluctuations to those of interplanetary magnetic fields (IMF) and the possible consequences of the magnetic helicity of IMF for the acceleration of cosmic rays are examined using experimental data from two neutron monitors and data on IMF in interplanetary space. The spectral tensor of IMF at two different distances from the Sun is determined for several selected intervals of 10–15 hours duration. Data from IMP-8 and Helios-1 are used. Cross correlations of IMF with cosmic rays measured by the Lomnický Štít neutron monitor, based on 5 min data, are estimated. A comparison of spectral slopes of the power spectrum density at the Lomnický Štít and Calgary neutron monitors demonstrates the possibility of using a single neutron monitor data point as a representative of the CR fluctuation power spectrum slope. It is shown that the data are not in all cases consistent with model of 3D turbulence in interplanetary space as the cause of the cosmic-ray fluctuation spectrum. Magnetic helicity, kinetic fluctuation energy, and the correlation length of the magnetic field are deduced from the limited amount of data and compared with values obtained by Matthaeus and Goldstein (1982). Based on the theoretical approach by Fedorovet al. (1992) the efficiency of acceleration of cosmic rays due to the presence of anisotropic reflective non-invariant IMF at various heliospheric distances is estimated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00612982
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  • 9
    Electronic Resource
    Electronic Resource
    Spatial distribution of albedo particles on altitudes ∼500 km (1985)
    Springer
    Czechoslovak journal of physics 35 (1985), S. 1371-1381 
    Details
    ISSN: 1572-9486
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Spatial distributions of energetic charged particles, neutrons and gamma rays at altitude ∼500 km (below the radiation belts of the Earth), obtained by the measurements of two apparatuses on board the Intercosmos-17 satellite, are presented. The latitudinal dependences, [i.e. the variation of flux with vertical cut-off rigidity of the measurement point], for neutrons (E n = 1 –30 MeV), gamma rays (E γ=0·15−6 MeV), secondary electrons (E e 〉 100 MeV) and for primary protons coming from the west and the east, respectively, are given. The main characteristic, the ratioN p/N e of the counting rate of the particles in the polar regionN p(Rvert〈 〈0·1 GeV/c) and on the equatorN e(Rvert 〉 16 GeV/c), is obtained for the various types of particles. This value is 10 for neutrons, 3.7 for gamma rays, 1·8 for electrons, 11 for protons in westward direction, 10 for protons in eastward direction. The latitude profile of neutrons and gamma rays is in a good agreement with calculations assuming their production by nuclear reactions of primary cosmic rays with nuclei of the atmosphere. The weakening of rigidity dependence of protons coming from east in comparison with those coming from the west, is interpreted as the cause of additional proton albedo flux. The equality of albedo electron fluxes (Ee = 100–3500 MeV) from these directions is observed. With the use of the shadowing effect the obtained data on electron-positron component are consistent with the flux of albedo positrons (Ee + 〉 3·5 GeV) of the value (0·5±0·2) m−2. s−1. ster−1. The possibility of abundance of albedo positrons above electrons at these altitudes for the energy intervalE=0·2÷0·3 GeV is indicated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01772719
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  • 10
    Electronic Resource
    Electronic Resource
    Response of the outer ionosphere to a magnetic storm at equinox (1995)
    Springer
    Studia geophysica et geodaetica 39 (1995), S. 425-448 
    Details
    ISSN: 1573-1626
    Keywords: Magnetic storm ; plasmasphere ; plasmapause ; outer ionosphere ; plasmatrough
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences , Physics
    Notes: Summary The observations of the ACTIVE Project satellites in the interval of March 17–23, 1990 were analyzed for the purpose of studying the response of the outer ionosphere to the magnetic storm with SSC on March 20 at 22.43 UT. In particular, measurements of thermal plasma parameters were used, but VLF broadband measurements and data on energetic ion and electron fluxes in the range of 17.7–272 keV were also available. The results of this case study show that the observations in the morning sector at altitudes around 2000 km reflect well the state of the plasmasphere during enhanced activity, namely the depth to which the plasmasphere has been affected by enhanced magnetospheric convection. They also provide the possibility of monitoring the initial phase of recovery. The early evening observations of the plasma parameters in the outer ionosphere at altitudes of 500–1000 km indicate a distinct trough in electron concentration. In the dusk sector, the equatorward edge of this trough can be assumed to be the projection of the equatorial plasmapause. This, combined with the occurrence of electron temperature peaks and with the morning plasmapause position, enables one to judge whether the plasmaspheric bulge has formed and whether an inner plasmapause has occurred.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02295896
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