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Ann. Geophys., 26, 1479-1490, 2008
www.ann-geophys.net/26/1479/2008/
© European Geosciences Union 2008
Space weather effects on radio propagation: study of the CEDAR, GEM and ISTP storm events
D. V. Blagoveshchensky1, A. S. Kalishin2, and M. A. Sergeyeva1
1University of Aerospace Instrumentation, 67, Bolshaya Morskaya, St. Petersburg, 190000, Russia
2Arctic and Antarctic Research Institute, 38, Bering Street, St. Petersburg, 199397, Russia
Abstract. The impact of 14 geomagnetic storms from a list of CEDAR, GEM and ISTP
storms, that occurred during 1997–1999, on radio propagation conditions has
been investigated. The propagation conditions were estimated through
variations of the MOF and LOF (the maximum and lowest operation frequencies)
on three high-latitude HF radio paths in north-west Russia. Geophysical
data of Dst, Bz, AE as well as some riometer data from Sodankyla
observatory, Finland, were used for the analysis. It was shown that the
storm impact on the ionosphere and radio propagation for each storm has an
individual character. Nevertheless, there are common patterns in variation
of the propagation parameters for all storms. Thus, the frequency range
Δ=MOF−LOF increases several hours before a storm, then it
narrows sharply during the storm, and expands again several hours after the
end of the storm. This regular behaviour should be useful for the HF radio
propagation predictions and frequency management at high latitudes. On the
trans-auroral radio path, the time interval when the signal is lost through
a storm (tdes) depends on the local time. For the day-time storms an
average value tdes is 6 h, but for night storms tdes is only 2 h.
The ionization increase in the F2 layer before storm onset is 3.5 h
during the day-time and 2.4 h at night. Mechanisms to explain the
observed variations are discussed including some novel possibilities
involving energy input through the cusp.
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