Emergence of a localized total electron content enhancement during the severe geomagnetic storm of 8 September 2017

Abstract

Abstract. In this work, the results of the analysis on total electron content (TEC) data before, during and after the geomagnetic storm of 8 September 2017 are reported. One of the responses to geomagnetic storms due to the southern vertical interplanetary magnetic field (Bz) is the enhancement of the electron density in the ionosphere. Vertical TEC (VTEC) from the Center for Orbit determination in Europe (CODE) along with a statistical method were used to identify positive and/or negative ionospheric storms in response to the geomagnetic storm of 8 September 2017. When analyzing the response to the storm of 8 September 2017 it was indeed possible to observe an enhancement of the equatorial ionization anomaly (EIA); however, what was unexpected was the identification of a local TEC enhancement (LTE) to the south of the EIA (∼40∘ S, right over New Zealand and extending towards the southeastern coast of Australia and also eastward towards the Pacific). This was a very transitory LTE that lasted approximately 4 h, starting at ∼ 02:00 UT on 8 September where its maximum VTEC increase was of 241.2 %. Using the same statistical method, comparable LTEs in a similar category geomagnetic storm, the 2015 St. Patrick's Day storm, were looked for. However, for the aforementioned storm no LTEs were identified. As also indicated in a past recent study for a LTE detected during the 15 August 2015 geomagnetic storm, an association between the LTE and the excursion of Bz seen during the 8 September 2017 storm was observed as well. Furthermore, it is very likely that a direct impact of the super-fountain effect along with traveling ionospheric disturbances may be playing an important role in the production of this LTE. Finally, it is indicated that the 8 September 2017 LTE is the second one to be detected since the year 2016.

Klobuchar, NeQuick G, and EGNOS Ionospheric Models for GPS/EGNOS Single-Frequency Positioning under 6–12 September 2017 Space Weather Events

“…Many applications relying on radio frequency transmission can be impacted by strong ionospheric perturbations [41]. The culmination of the analysed storm took place on 8 September 2017 and was caused by an X-ray solar flare [42]. This was the most powerful flare of the 24 solar cycle and the strongest flare in a decade.…”

Extreme Positive Ionosphere Storm Triggered by a Minor Magnetic Storm in Deep Solar Minimum Revealed by FORMOSAT‐7/COSMIC‐2 and GNSS Observations

“…Indeed, for the positive storm responses in the event shown in this study, there are ∼800% enhancement in the confined regions in the midlatitude, however, for a fair comparison, only the magnitude of peak‐to‐peak variations of EIA crests is displayed in the figures. Though a magnetic storm was recorded during September 7–8, 2017 with lower solar activity period, and it did produce about 240% enhancement of TEC (Sotomayor‐Beltran & Andrade‐Arenas, 2019), the storm was classified as a severe G4 storm with Dst reaching about −150 nT. Further, the peak‐to‐peak variations of the EIA crests by the storm was about a factor of 2.…”