Effects of Geomagnetic Disturbances in Power Spectra of Atmospheric Waves in the Dynamo Region of the Ionosphere

Mikhailova G.A.1, Mikhailov Yu.M.1, Kapustina O.V.1, Smirnov S.E.2
  1. Institute of Terrestrial Magnetism, Ionosphere, and Radiowave Propagation, Russian Academy of SciencesTroitsk, Moscow oblast, e-mail: yumikh@izmiran.ru
  2. Institute of Cosmophysical Research and Radiowave Propagation, Far East Division, Russian Academy of Sciences, v. Paratunka, Kamchatka region, e-mail: sergey@ikir.kamchatka.ru

The dynamics of wave disturbances in the ionosphere E region in the band of periods of thermal tidal waves
and waves of planetary scales (T = 48, 72, and 192 h) has been studied based on the variations in the horizontal
component of the geomagnetic field, observed at Paratunka and Barrow observatories in September-October
1999. It has been found that, at midlatitudes during high geomagnetic activity, the intensity of oscillations in
the power spectra with T=24 and 12 h varies with a periodicity of 16 days different from the periodicity of
changes in the Kp index. The maximum deviations of these periods from the values under quiet conditions
coincide with the maximum changes in the Kp index. The variations in the 48-192 h band of periods (espe-
cially with T ∼ 192 h) intensify simultaneously with the increasing geomagnetic activity. The intensity of this
harmonic is several times as high as that of the harmonic with T ∼ 24 h. The periodicity of changes in the
harmonics intensity within the 48 – 192 h band coincides with the periodicity of changes in the Kp index. In
the polar ionosphere, the effect of high geomagnetic activity is observed as an increase in the variations with a
quasi-period of T ∼ 24 h and as an appearance of variations in the 48-192 h band with the periodicity coinciding
with the maximums in the Kp index variations.