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Observations of Pc 3-4 and Pi 2 geomagnetic pulsations in the low-latitude ionosphere

Observations of Pc 3-4 and Pi 2 geomagnetic pulsations in the low-latitude ionosphere,R. A. Marshall,F. W. Menk

Observations of Pc 3-4 and Pi 2 geomagnetic pulsations in the low-latitude ionosphere   (Citations: 9)
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Day-time Pc 3-4 (5-60 mHz) and night- time Pi 2 (5-20 mHz) ULF waves propagating down through the ionosphere can cause oscillations in the Doppler shift of HF radio transmissions that are correlated with the magnetic pulsations recorded on the ground. In order to examine properties of these correlated signals, we conducted a joint HF Doppler/ magnetometer experiment for two six-month intervals at a location near L = 1.8. The magnetic pulsations were best correlated with ionospheric oscillations from near the F region peak. The Doppler oscillations were in phase at two diÄerent altitudes, and their amplitude increased in proportion to the radio sounding frequency. The same results were obtained for the O- and X-mode radio signals. A surprising finding was a constant phase diÄerence between the pulsations in the ionosphere and on the ground for all frequencies below the local field line resonance frequency, independent of season or local time. These observations have been compared with theoretical predictions of the amplitude and phase of ionospheric Doppler oscillations driven by downgoing Alfven mode waves. Our results agree with these predictions at or very near the field line resonance frequency but not at other frequencies. We conclude that the majority of the observations, which are for pulsations below the resonant frequency, are associated with downgoing fast mode waves, and models of the wave-ionosphere interaction need to be modified ac- cordingly.
Published in 1999.
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    • ...According to the Doppler observations of Pc3‐4 and Pi2 geomagnetic pulsations in the low‐latitude ionosphere [Marshall and Menk, 1999; Menk et al., 2007], most of these pulsations at frequencies below the local field‐ line resonant frequency were associated with downgoing fast‐mode waves...

    V. Pilipenkoet al. An analytical model for Doppler frequency variations of ionospheric HF...

    • ...Cross-correlation analysis is able to reveal a possible direct relationship between ionospheric and geomagnetic oscillations, which was previously described between short period ionospheric waves and geomagnetic micropulsations (e.g. Marshall and Menk, 1999)...

    Tereza Šindelářováet al. Observations of acoustic-gravity waves in the ionosphere generated by ...

    • ...In addition to these contributions from incident Alfven waves, some workers [Menk et al., 1995; Marshall and Menk, 1999] suggested that the pulsation-associated Doppler oscillations at the middle/low latitudes are directly affected also by compressional waves propagating toward the middle-/low-latitude ionosphere across field lines...

    Tetsuo Motobaet al. HF Doppler oscillations in the low-latitude ionosphere coherent with e...

    • ...In addition to these contributions from incident Alfven waves, some workers [Menk et al., 1995; Marshall and Menk, 1999] suggested that the pulsation-associated Doppler oscillations at the middle/low latitudes are directly affected also by compressional waves propagating toward the middle-/low-latitude ionosphere across field lines...

    Tetsuo Motobaet al. HF Doppler oscillations in the low-latitude ionosphere coherent with e...

    • ...In spite of many years of theoretical and experimental research, it has not yet been possible to conclusively elucidate the mechanisms [6, 9, 10] accounting for the relationship between short-period variations in frequency Doppler shift of the ionosphere-reflected radio signal and geomagnetic pulsations...
    • ...One of the reasons for this, as suggested by the authors of [10], has to do with the difficulty in obtaining statistically significant sets of experimental data...
    • ...This is confirmed by simultaneous recordings of variations in frequency Doppler shift fd of the ionosphere-reflected radio signal and geomagnetic pulsations [1-3, 6, 9, 10, 14]...
    • ...It should be noted that the mechanisms accounting for the correlation between geomagnetic pulsations and fd variations still remain unclear [9, 10]...
    • ...This value is consistent with results (from 0.01 Hz/nT to 0.4 Hz/nT) obtained in [2, 10]...

    Yu. V. Lipkoet al. Ionospheric manifestations of geomagnetic pulsations at high latitudes

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