  We report simultaneous observations of intense fluxes of quasi-trapped
energetic electrons and substantial enhancements of ionospheric electron
concentration (EC) at low and middle latitudes over Pacific region during
geomagnetic storm on 15 December 2006. Electrons with energy of tens of keV
were measured at altitude of ~800 to 900 km by POES and DMSP satellites.
Experimental data from COSMIC/FS3 satellites and global network of ground-based
GPS receivers were used to determine height profiles of EC and vertical total
EC, respectively. A good spatial and temporal correlation between the electron
fluxes and EC enhancements was found. This fact allows us to suggest that the
quasi-trapped energetic electrons can be an important source of ionospheric
ionization at middle latitudes during magnetic storms.
