The ionosphere as a natural detector for studying long-period variations in the fluxes of solar geoeffective radiation

摘要

A method for determining the fluxes of solar extreme ultraviolet (EUV) based on measurements of the E region critical frequencies and calculations of the ionospheric activity index is proposed. The error of irradiance determination is similar to 7%. This makes it possible to study long-term variations in EUV and to extend the time interval of studies. The use of the ionospheric index indicates that considerable trends in EUV during 1957-2003 are absent.