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Ann. Geophys., 20, 1751-1761, 2002
www.ann-geophys.net/20/1751/2002/
© European Geosciences Union 2002
Bursts of ULF noise excited by sudden changes of solar wind dynamic pressure
V. Safargaleev1, J. Kangas2, A. Kozlovsky2, and A. Vasilyev1
1Polar Geophysical Institute, 184200 Apatity, Russia
2Sodankyla Geophysical Observatory, FIN-99600 Oulu, Finland
Correspondence to: A. Kozlovsky
(alexander.kozlovsky@oulu.fi)
Abstract. We present the results of
analysis of the dayside magnetic pulsation response to a sudden change in solar
wind dynamic pressure. We concentrate on the events when a burst or a series of
short-lived bursts in the Pc1 frequency range with the repetition period of 7–15
min were observed on the ground around the local noon. Not every impulse of
large amplitude caused this phenomenon. We have found that the ULF bursts were
excited when the spectrograms of the DMSP satellites showed a signature of 10–30
keV ions in the vicinity of the magnetic flux tube of the ground observatory,
that may be related to a geomagnetic storm preceding the event. In light of
this finding a possible model of the phenomenon is suggested in which the hot
protons influence significantly both the generation and modulation of Pc1
activity.
Key words. Magnetospheric physics (solar wind –
magnetosphere interaction; MHD waves and instabilities; storms and substorms)
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