Distinctive effects of interplanetary electric field and substorm on nighttime equatorial F layer: A case study

Abstract

[1] A geomagnetic storm event is identified wherein the base of the equatorial F layer (h 0 F) over dip equator moved unusually upward till premidnight hours and descended thereafter. The h 0 F variation is linearly correlated with the variation in the smoothed auroral electrojet index (AE) which varies slowly. The fast fluctuations (residuals) with periodicity $42 min in the vertical plasma drift are found to be causally related with the fast fluctuations in the dawn-todusk component of interplanetary electric field (IEFy) and interestingly, not with the fast fluctuations in AE. However, during the interval when a substorm was triggered in association with sharp transitions in IEFy polarity, the drift fluctuations follow the AE fluctuations and are out of phase with IEFy fluctuations. The investigation demonstrates distinctive effects of IEFy and substorm-related current systems on the zonal electric field over dip equator in the premidnight hours during geomagnetic storms.

Solar wind flow angle and geoeffectiveness of corotating interaction regions: First results

“…Therefore, although it is clear that the frequency response around the ring current region decides the prompt penetration frequency, the nature [e.g., Ohtani and Uozumi , ] of the processes that controls this response is not comprehensively understood. Nevertheless, the present study (Table ) shows that on some occasions, DP2 (30 and 60 min periodicities) type [ Nishida , ; Sastri et al , ; Chakrabarty et al , , ] periodic fluctuations can reach up to dip equatorial ionosphere in daytime during the passage of CIRs.…”

Significant Electric Field Perturbations in Low Latitude Ionosphere due to the Passage of Two Consecutive ICMEs During 6–8 September 2017

“…As the shielding currents do not get sufficient time to develop during time‐varying disturbances, the penetration may last for several hours (e.g., Fejer et al., ; Garner, ; Maruyama et al., ). Such long duration penetration events are reported on some occasions (e.g., Chakrabarty et al., , , ; Huang, Foster, et al., ). In the present investigation, also, the DP2‐type PP is observed to last for about 10 hr during the passage of ICME‐1 sheath region.…”

“…During geomagnetic disturbances, low latitude ionosphere gets affected by several types of electric fields perturbations: prompt electric field perturbations associated with magnetospheric convection (e.g., Chakrabarty et al., ; Jaggi & Wolf, ; Tsurutani et al., ), substorm (Chakrabarty et al., ; Hashimoto et al., , ; Huang, ), overshielding‐OS (Hashimoto et al., ; Kikuchi et al., ; Sekar & Chakrabarty, ), ram pressure (Huang et al., ; Rout et al., ), and delayed electric field perturbations due to disturbance dynamo‐DD (e.g., Blanc & Richmond, ; Fejer & Emmert, ; Maruyama et al., ; Pandey et al., ). During southward conditions of Interplanetary Magnetic Field (IMF) Bz, the effects of the fast fluctuations in the Y component (dawn‐dusk) of solar wind/interplanetary electric field (IEFy) can reach up to low‐equatorial latitudes as the time constant of the shielding region at the inner edge of the ring current is much larger than the time constant associated with the magnetospheric convection.…”

Extreme changes in the equatorial electrojet under the influence of interplanetary electric field and the associated modification in the low‐latitude F region plasma distribution

“…In the context of the shielding and overshielding phenomena, this event is important because the overshielding occurred during the storm main phase. As we know, the overshielding events are known to trigger recovery phase of the geomagnetic storms and trigger the substorms, or trigger the recovery of substorms [e.g., Chakrabarty et al , 2008; Kikuchi et al , 2008; Veenadhari et al , 2010]. Unlike this, the event reported here occurs in the main phase of the storm, and the main phase continues even after the overshielding event.…”