X-ray and EUV radiation of solar flares and its ionospheric response on GNSS measurments

Abstract

The Earth’s ionosphere is primarily generated by solar EUV radiation and X-rays. Whereas higher energetic X-rays penetrate down to the D region ionosphere, EUV radiation causes an enhanced ionization in the upper E and F region. During a solar flare, we observe a sudden release of energy distributed over the whole electromagnetic spectrum, but the spectral distribution may vary strongly from flare to flare. The present poster demonstrates the variable ratio of X-ray and EUV radiation components during selected solar flares recorded by the GOES and SDO satellites and the associated different influences on the ionosphere found in GNSS (Global Navigation Satellite System) and GIFDS (Global Ionospheric Flare Detection System) measurements. The dual-frequency GNSS measurements can effectively be used to derive the total electron content (TEC) of the ionosphere. Our investigation shows that the first derivative of the vertical TEC is a good indicator for EUV flares. Furthermore, the solar zenith angle dependence of flare induced ionization enhancements in GNSS measurements is presented.