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  • 1
    ISSN: 0992-7689
    Keywords: Electromagnetics (wave propagation) ; Magnetospheric physics (magnetospheric configuration and dynamics; MHD waves and unstabilities)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Simultaneous whistler records of one station and geomagnetic pulsation (Pc3) records at three stations were compared. In a previous study correlation was found between occurrence and L value of propagation/excitation for the two phenomena. The recently investigated simultaneous records have shown that the correlation is better on longer time scales (days) than on shorter ones (minutes), but the L values of the propagation of whistlers/excitation of pulsations are correlated, i.e. if whistlers propagate in higher latitude ducts, pulsations have periods longer than in the case when whistlers propagate in lower latitude ducts.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Annales geophysicae 15 (1997), S. 1604-1614 
    ISSN: 0992-7689
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The present study is based on simultaneous measurements of the atmospheric electric potential gradient (PG) and Schumann resonances at Nagycenk station (Hungary) from 1993 to 1996. Annual and semiannual variations detected previously in the relative amplitudes of Schumann resonances (SR) in the first three modes are confirmed by the extended data series applied here. The regular annual variation found in the PG (with winter maximum and summer minimum) is in the opposite phase, compared to that of the SR amplitudes. Nevertheless, even the PG (being a parameter of the DC global circuit) occasionally shows a distinct secondary peak in summer as indicated by the results of the present analysis (and corresponding to a recent study on further parameters of the DC global circuit). In spite of the presumed dominance of local influence over the global one, a suitable PG parameter correlates well with SR (representing the AC global circuit) on the annual time scale. It also became evident that a semiannual variation (with spring and autumn maxima and winter and summer minima) is generally present in SR. Certain signatures of a semiannual variation have also been revealed in the PG, however, the phase of this semiannual variation does not fit the pattern shown by SR (and tropical surface air temperature, respectively). The representativeness of the PG data has also been checked by means of a single day’s diurnal variations displaying a phase corresponding to that of the ‘Carnegie Curve’. Additionally, the coincidence of short-term changes (lasting some hours) both in the SR and the PG parameter is also demonstrated on a day disturbed by local factors. The results are discussed in the context of correlations between surface air temperature and parameters of the atmospheric electric global circuit shown by previous studies.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0992-7689
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Using data on the occurrence frequency of geomagnetic pulsations of different periods from three observatories in Central Europe, conclusions are drawn about the occurrence of field line resonances and pulsations directly driven by upstream waves at L-values below 3. It was found that both types occur during the interval studied (first 6 months of the year 1991), but both the occurrence frequency of the two types and the characteristic period of the field line resonance change significantly as compared to other intervals. During Northern winter, pulsation activity is severely damped in solar maximum years, including the year 1991. The decrease in the activity of the pulsations is more significant at shorter periods.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    GeoJournal 30 (1993), S. 486-490 
    ISSN: 1572-9893
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography
    Type of Medium: Electronic Resource
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