PROBLEMS OF GEOCOSMOS

Proceedings of the 7th International Conference "Problems of Geocosmos" (St. Petersburg, Russia, 26-30 May 2008)
Fig. 4 The same as in Fig. 3(right panel) for magnetic storms on October 13-14, 2000 and May
23-24, 2000
activity may be mapped or inside of the auroral oval, or in the polar cap region, i.e. under the open
geomagnetic field lines (Fig. 5).
Kozyreva et al. (2004) reported that the storm initial phase as well as its sudden commencement (SC),
caused by a passage of the compression front edge of an interplanetary magnetic cloud, manifests itself
mainly as wave magnetic disturbances at dayside polar cap latitudes. We studied a response of Ez and Jz
variations, observed at Hornsund, to the SC and the initial phase of the large magnetic storm on July 15,
2000. This storm was associated with
the powerful coronal mass ejection
(CME). The observations (Fig. 6)
demonstrate the occurrence of the
very strong (up to ~ 800 V/m) positive
bursts of Ez and Jz following the
sudden jump of the solar wind
dynamic pressure and the IMF B
corresponding to the bow shock
impact (magnetic storm sudden
commencement - SC. The positive Ez
and Jz enhancement was observed
Fig. 5 The location of Hornsund relatively to auroral oval under the significant cross-polar cap
position (OVIATION data)
potential drop. The amplitude of Ez
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