Multi‐Instrument Investigation of the Impact of the Space Weather Events of 6–10 September 2017

• Published in: Space weather Vol. 19; no. 12
• Main Authors: Amaechi, Paul O., Akala, Andrew O., Oyedokun, Johnson O., Simi, K. G., Aghogho, O., Oyeyemi, Elijah O.
• Format: Journal Article
• Language: English
• Published: Washington John Wiley & Sons, Inc 01.12.2021
• Subjects: Corona Mass Ejection; Coronal mass ejection; E region; Electric currents; Electrojets; Equatorial electrojet; Gas pipelines; Geomagnetic field; Geomagnetic storms; Geomagnetism; Global navigation satellite system; Global positioning systems; GPS; Instrument approach; Ionosondes; Ionospheric currents; Ionospheric electron content; magnetic crochet; Magnetic storms; Magnetometers; Magnetospheres; Magnetospheric-solar wind relationships; Natural gas; Navigation satellites; Navigation systems; Petroleum pipelines; Pipelines; Risk levels; Solar corona; Solar flare effects; Solar flares; Solar wind; Space weather; Storms; Total Electron Content; X‐class solar flare; Ascension Island
• ISSN: 1542-7390; 1539-4964; 1542-7390
• DOI: 10.1029/2021SW002806

We analyzed the space weather events of 6–10 September 2017 using the multi‐instrument approach. We focused on the four X‐class flares which emanated from the Active Region AR 12673 and the Ground Induced Currents hazard associated with the geomagnetic storm of 7–8 September 2017. The flare effect on the equatorial electrojet (EEJ) recorded on board the SWARM satellite and on the horizontal component of the geomagnetic field (H) records of ground‐based magnetometers was further examined. During the X2.2/X1.3 flares of 6/7 September, the maximum percentage Global Navigation Satellite System (GNSS) vertical Total Electron Content (VTEC) increase was 6.9%/5.0% in Dakar/Porto Velho. During the X9.3/X8.2 flare of 6/10 September it was 7.9%/18.8% in Ascension Island/Kourou. The strongest Solar Flare Effect occurred in Mbour and Kourou during the respective flare. However, the highest EEJ increase was observed during the X2.2 and X9.3 flares. Interestingly, the X.9.3 flare resulted in a stronger ionospheric response than the X8.2 flare. Furthermore, global TEC map showed a higher response in the African and South American longitude during the respective event. The total radio fade‐out lasted from 30 to 90 min at the Hermanus and Sao Luis ionosondes during the flares, while the risk level to critical ground infrastructures based on the geomagnetically induced currents hazard was very low risk. Our results highlight the potential GPS positioning errors induced by sudden increase in TEC and the loss of high‐frequency communication and GNSS navigation signals associated with these solar events. Plain Language Summary Space weather refers to changes on the Sun, solar wind and magnetosphere that can affect the performance of technological systems in space and on ground. Solar flares and coronal mass ejections are typical examples of space weather. Several Coronal Mass Ejections (CMEs) and solar flares occurred in the month of September 2017. We have focused on the X‐class solar flares of 4–10 September and the Ground Induced Currents (GICs) related with the geomagnetic storm of 7/8 September. The X9.3/X8.2 flare had enhanced the ionospheric total electron content by about 7.9%/18.8% in Ascension Island/Kourou on 6/10 September. The highest sudden increase in the horizontal component of the geomagnetic field was observed in Mbour and Kourou during the respective flare. The largest changes in ionospheric current in the E region occurred during the X2.2 and X9.3 flares on 6 September. The flares also caused total radio fade‐out for over 30–90 min at the Hermanus and Sao Luis ionosondes. The GICs however, represented a low risk to critical ground infrastructures such as power grids, as well as oil and gas pipelines. Key Points The X9.3/X8.7 flare induced peak vertical Total Electron Content increase of 7.9%/18.8% in Ascension Island/Kourou with rise time of 2/9 min The total radio fade‐out lasted from 30 to 90 min at the Hermanus and Sao Luis ionosondes during the flares The risk level to critical ground infrastructures based on the Ground Induced Current hazard was very low at the low‐latitude