Extreme solar events and magnetic storms in October 2003 and their manifestations in the midlatitude ionosphere

O. M. Raspopov
Institute of Terrestrial Magnetism, Ionosphere and Radiowaves Propagation, St. Petersburg Filial, St. Petersburg, Russia

Abstract

[1]  Effects of the extreme solar phenomena and magnetic storms on 28-30 October 2003 in the midlatitude ionosphere are studied on the basis of the disturbances of the VLF signals at midlatitudinal paths and geophysical situation in the magnetosphere and ionosphere. The aim of the study was, on one hand, to reveal ionospheric effects in variations of the electron concentration in the lower ionosphere and, on the other hand, monitoring of the shift of the region of auroral processes into middle latitudes during magnetic storms, where there is no other types of observations of these phenomena. The estimate of VLF fields on the disturbance model of the ionosphere shows an increase by an order of magnitude in the electron concentration in the sunlit conditions during an X-ray flare and a descent of the ionosphere at night at middle latitudes during the magnetic storm. The latter fact indicates that there are injections into the ionosphere of electrons with energies of tens (and probably hundreds) keV. Joint analysis of the data on VLF signals, structure, and dynamics of the magnetosphere and also auroral and geomagnetic activity shows that in the evening UT hours on 29 and 30 October 2003, there is a splitting of the region of auroral processes to two distanced latitude zones located at geomagnetic latitudes above 48-55^o and 38-46^o.

Received 5 April 2005; revised 7 March 2006; accepted 11 April 2006; published 29 June 2006.

Keywords: Ionospheric storms; Auroral processes; Electron concentration variations.

Index Terms: 2431 Ionosphere: Ionosphere/magnetosphere interactions; 2788 Magnetospheric Physics: Magnetic storms and substorms; 2716 Magnetospheric Physics: Energetic particles: precipitating.