ИСТИНА

Geomagnetic storms are often accompanied by increases of electron density in the F2-region of low-latitude ionosphere, so-called positive ionospheric storms. We focus on problem concerning time variations and possible causes of the positive storms, which are still poorly understood. We consider positive storm effects along with magnetospheric manifestations of geomagnetic storm over Pacific Ocean. For this study we have collected more than 70 modest/major geomagnetic storms from 1999 to 2006 years and use a combination of ground-based GPS vertical total electron content (VTEC) and electron density profiles provided by GPS radio occultation from COSMIC satellites. We classify all the events on three groups of the effects over the Pacific region: a) simultaneous ionospheric and magnetospheric effects; b) only ionospheric effects; c) only magnetospheric effects. We have defined the external solar wind conditions under which the ionospheric and magnetospheric effects could be coupled. We showed that in the case (a) the observed ionization enhancements can be related to a mechanism of magnetospheric origin.