Influence of the solar hydrogen Lya line on the GNSS signal delay in the ionospheric D-region

Abstract

Recent research indicates that the influence of the ionospheric D-region on the propagation of satellite signals cannot be ignored during the intense X-radiation emitted during solar X-ray flares. In this paper, we investigate the influence of changes in the solar hydrogen Lya radiation, which is manifested in variations of the D-region electron density and, consequently, the total electron content in this region, on the propagation of the Global Navigation Satellite System (GNSS) signals. We consider changes during a solar cycle and year, represented by the smoothed daily sunspot number and the day of year. The obtained results indicate that the influence of the D-region on these signals is not negligible for positioning with a single signal recorded by a single receiver during the period around the maximum of a solar cycle.