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.
The strength and hemispheric asymmetry of Equatorial Ionization Anomaly during two geomagnetic storms in 2013 from Global Ionosphere Map and SAMI2
