Equatorial ionospheric variations caused by different large-scale solar wind structures

     The paper presents the analysis of critical frequency foF2 variations and
   virtual height h'F at equatorial and ionospheric stations during
   geomagnetic storms of different nature. It is well known, that ionospheric
   parameter variations and generation of ionospheric irregularities during
   geomagnetic storms considerably affect signal propagation and satellite
   devices. Yohkoh, SOHO, Ulysses mission observations of the Sun and the
   solar wind allow us to predict the types of flows in the solar wind,
   approaching to the Earth's orbit, and their characteristics 2-3 days
   before the event. We identified geomagnetic storms and caused by them
   ionospheric variations according to the current classification of flow
   types in the solar wind. During the first stage we distinguished two types
   of geomagnetic storms determined by large-scale coronal mass ejections and
   solar wind fast flows from coronal holes. The paper presents the results
   of comparison of ionospheric variations caused by these two sources in the
   solar wind. The obtained conclusions allow us to suggest, that
   investigation of geomagnetic and ionospheric variations from the known
   quasi-stationary and sporadic large-scale types of flows in the solar wind
   and during different phases of solar activity are perspective for the
   method of medium-term forecast of ionospheric storminess based on current
   investigations of the Sun and the solar wind.