Prompt Penetration and Substorm Effects Over Jicamarca During the September 2017 Geomagnetic Storm

Abstract

We used reanalyzed Jicamarca radar measurements to study the response of equatorial ionospheric electrodynamics and spread F during the main phase of the large September 2017 geomagnetic storm. Our observations near dusk on 7 September show very large upward drifts followed by a large short‐lived downward drift perturbation that completely suppressed the lower F region plasma irregularities and severely decreased the backscattered power from the higher altitude spread F. We suggest that this large short‐lived westward electric field perturbation is most likely of magnetospheric origin and is due to a sudden and very strong magnetic field reconfiguration. Later in the early night period, data indicate large, mostly upward, drift perturbations generally consistent with standard undershielding and overshielding electric field effects, but with amplitudes significantly larger than expected. Our analysis suggests that occurrence of storm‐time substorms is one of the major factors causing the large nighttime westward and eastward electric field perturbations observed at Jicamarca near the storm main phase. Our analysis also suggests that magnetospheric substorms play far more important roles on the electrodynamics of the equatorial nighttime ionosphere than has generally been thought.

Signatures of Equatorial Plasma Bubbles and Ionospheric Scintillations from Magnetometer and GNSS Observations in the Indian Longitudes during the Space Weather Events of Early September 2017

“…Geomagnetic storms may occur during the southward polarity of the interplanetary magnetic field (Bz) that manipulates the regular equatorial electric fields to trigger pre-reversal enhancements (PREs) to seed the generation and development of plasma bubbles [2][3][4]. Additionally, the substorms formed at the polar latitudes can alter the equatorial electric field during the recovery of geomagnetic storms resulting in an increase or decrease in the scintillation activity [5][6][7][8]. Generally, the ionospheric electrodynamics during the geomagnetic storms are affected by two sources: (1) the short-lived penetrating electric fields from high to low latitudes corresponding to the southward turning of the interplanetary magnetic field Bz to drive eastward (westward) the polarized disturbances at the day and evening sectors (nightside) [9][10][11][12]; and (2) the disturbance dynamo electric fields (DDEFs) resulting from the changes in neutral winds that develop a few hours after the onset of the storm and usually last for several hours via thermospheric wind dynamo action, often dominating in the recovery phase [13,14].…”

“…The space weather event of 6-10 September 2017 was a complex event associated with multiple X-and M-class solar flares and severe geomagnetic storms, when the GNSS signals witnessed pronounced post-sunset scintillations due to strong EPB irregularities. The occurrences of plasma density irregularities, their drifting characteristics, and the mechanisms responsible for this occurring over different longitude sectors during the storm of September 2017 have been widely investigated in the earlier literature [3,8,[44][45][46][47][48][49][50][51]. From the investigation of the topside ionospheric conditions during this particular storm period, with uplooking GNSS TEC from the observations retrieved from TerraSAR-X, GRACE, Swarm, and MetOp-A, and the in situ electron density (Ne) from the Swarm satellite, Jimoh et al [50] reported night-time ROTI enhancements across a wide latitudinal range during the main phase of the storm.…”

A Method to Mitigate the Effects of Strong Geomagnetic Storm on GNSS Precise Point Positioning

“…Since two solar flares X2.2 and X9.3 erupted over the active region 2673 on 6 September 2017, a strong geomagnetic storm with double main phases was generated on 8 September 2017 (Yamauchi et al., 2018). Based on the observations derived from GNSS receivers, radars, and ionosondes, numerous studies have investigated the complex responds of ionosphere at different latitudes to this strong storm (Aa et al., 2018; Fejer et al., 2021; Habarulema et al., 2020; Li et al., 2018; Xiong et al., 2019).…”

“…3 of 13 the complex responds of ionosphere at different latitudes to this strong storm (Aa et al, 2018;Fejer et al, 2021;Habarulema et al, 2020;Li et al, 2018;Xiong et al, 2019).…”

Ground-Based Augmentation System Operation in Low Latitudes - Part 2: Space Weather, Ionospheric Behavior and Challenges

“…giving rise to the so-called "Region 2" currents near the equatorial plane in the ionosphere and creating a partial dusk-to-dawn electric field that tends to shield the near-Earth region opposing the convection in the inner magnetosphere. These shielding electric fields immediately alter the electrodynamics over low-latitude regions significantly (Abdu et al 2009a;2012;2016;Fejer et al 2021;Kelley et al 1979a;Kikuchi et al 2008;Peymirat et al 2000). This aspect must be considered every time a space weather evaluation is carried out but may be taken into account indirectly through other parameters to be discussed later.…”