The 6 September 2017 X-class solar flares and their impacts on the ionosphere, GNSS and HF radio wave propagation

Wednesday, 13 February 2019
Fountain III/IV (Westin Pasadena)
Elvira Astafyeva1, Yuryi Yasyukevich2, Artem M Padokhin3, Vera Ivanova2, Semen Syrovatskii2 and Aleksey Podlesnyi2, (1)Institut de Physique du Globe de Paris, Paris, France, (2)Institute of Solar-Terrestrial Physics SB RAS, Irkutsk, Russia, (3)Moscow State University, Moscow, Russia
Abstract:
On 6 September 2017, the Sun emitted two significant solar flares (SF). The first SF, classified X2.2, peaked at 09:10UT. The second one, X9.3, which is the most intensive SF in the current solar cycle, peaked at 12:02UT, and was accompanied by solar radio emission (SRE). In this work, we study ionospheric response to the two X-class SF, and their impact on the Global Navigation Satellite Systems (GNSS) and high-frequency (HF) propagation. We compare the effects of the September 2017 SRE with those due to past events.

Our results show that the 6 September 2017 X2.2 SF caused an increase of 2-4 TECU in the dayside vertical total electron content (TEC). The X9.3 SF produced a sudden increase of ~8-10 TECU at mid-latitudes and of ~15-16 TECU enhancement at low latitudes. These vertical TEC enhancements lasted longer than the duration of the EUV emission. Further, analysis of the impact of the two SF on the GNSS-based navigation showed that the SF did not cause losses-of-lock in the GPS, GLONASS or Galileo systems, while the positioning error increased by ~3 times in GPS precise point positioning solution, and even more for the GLONASS solution. The two X-class SF had an impact on HF radio wave propagation causing blackouts at <30 MHz in the subsolar region and <15 MHz in the post-midday sector.

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