Journal cover Journal topic
Annales Geophysicae An interactive open-access journal of the European Geosciences Union
Journal topic

Journal metrics

Journal metrics

  • IF value: 1.490 IF 1.490
  • IF 5-year value: 1.445 IF 5-year
    1.445
  • CiteScore value: 2.9 CiteScore
    2.9
  • SNIP value: 0.789 SNIP 0.789
  • IPP value: 1.48 IPP 1.48
  • SJR value: 0.74 SJR 0.74
  • Scimago H <br class='hide-on-tablet hide-on-mobile'>index value: 88 Scimago H
    index 88
  • h5-index value: 21 h5-index 21
Volume 17, issue 11
Ann. Geophys., 17, 1397–1410, 1999
https://doi.org/10.1007/s00585-999-1397-2
© European Geosciences Union 1999
Ann. Geophys., 17, 1397–1410, 1999
https://doi.org/10.1007/s00585-999-1397-2
© European Geosciences Union 1999

  30 Nov 1999

30 Nov 1999

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

R. A. Marshall1,2 and F. W. Menk1,3 R. A. Marshall and F. W. Menk
  • 1Department of Physics, the University of Newcastle, Callaghan, NSW 2308, Australia
  • E-mail: physpuls3@cc.newcastle.edu.au
  • 2IPS Radio and Space Services, PO Box 1386, Haymarket, NSW 1240, Australia
  • 3Also at Cooperative Research Centre for Satellite Systems, Canberra, ACT, Australia

Abstract. 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 different 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 difference 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 Alfvén 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 accordingly.

Key words. Ionosphere (ionosphere irregularities) · Magnetospheric physics (magnetosphere-ionosphere interactions) · Radio science (ionospheric physics)

Publications Copernicus
Download
Citation