Anomaly effects of 6–10 September 2017 solar flares on ionospheric total electron content over Saudi Arabian low latitudes

Abstract

Solar flares are sudden eruption of intense high-energy radiation from the Sun causing radio perturbations due to disturbances in ionosphere and magnetosphere of the Earth. The present paper investigates ionospheric response to a series of X- and M-class solar flares during 6–10 September 2017 with simultaneously extracted total electron content (TEC) from six global positioning system (GPS) observatories around Saudi Arabian low latitudes. These solar flares include the most significant event of the 24th solar cycle and the brightest one in the past ten years. The results show noticeable enhancement in TEC magnitudes with the flare induced geomagnetic storms as compared to the average nearest quiet days. An abrupt increase in TEC (~132%) is observed at the eastward location in Oman with a time lag of about 1 h from the brightest solar flare (X9.3) whereas other sites depict increments within 22%–78%, referring to a longitudinal asymmetry during the period. However, a remarkable deviation from the quiet time TEC is visible at all stations about 24 h after the event, with the maximum and the least positive differences in TEC at the westward Israel (~141%) and the southward Djibouti (23%) stations, respectively. Comparable levels of TEC (~200%–300%) were also seen at far equatorial locations after the M-class flare on September 8, 2017, corroborating to the conjugate effects of solar flares and coronal mass ejections (CMEs) induced geomagnetic storms and O/N2 changes. Interestingly, the second brightest solar flare (X8.2) appeared to be less effective confirming a negative ionospheric response at the eastern side during the nighttime hours.