ИСТИНА

Observations by low Earth orbital satellites revealed sudden increases of the energetic electrons in the equatorial topside ionosphere during enhanced substorm activity and magnetic storms. Significant ionizing effect of the energetic electrons at low latitudes was found during some major and minor geomagnetic storms. Statistics, accumulated during solar minimum years of the cycle 23, show a regular occurrence of the phenomenon. The enhanced fluxes of energetic electrons at equatorial latitudes during even non-storm conditions indicate that some ionospheric effects such as day-to-day variability, F3 layer, and equatorial spread F might also be related to direct ionization impact of energetic electrons on the ionosphere/thermosphere system at low latitudes. The coupling of enhanced energetic electrons penetrating into the equatorial ionosphere with ionospheric effects needs further investigations and testing with direct observations and models.