Statistical analysis of dayside equatorial ionospheric electric fields and electrojet currents produced by magnetospheric substorms during sawtooth events

Huang, Chao‐Song

doi:10.1029/2011ja017398

Cited by 33 publications

(54 citation statements)

References 49 publications

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“…Second, during this period of time the sub-storm activity was less intensive than during the initial phase of the storm, which could play a role on the efficiency of the PPEF. It is known that substorms can enhance the PPEF or can serve themselves as a source of PPEF (Huang 2012). Finally, the longitudinal The second positive storm on the nightside correlates well with a new increase of the counter electrojet, especially in data of SWA and SWC (rows VIII and IX), i.e., in the same manner as during the first sub-event.…”

Section: Resultsmentioning

confidence: 66%

Prompt penetration electric fields and the extreme topside ionospheric response to the June 22–23, 2015 geomagnetic storm as seen by the Swarm constellation

2016

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Using data from the three Swarm satellites, we study the ionospheric response to the intense geomagnetic storm of June 22-23, 2015. With the minimum SYM-H excursion of −207 nT, this storm is so far the second strongest geomagnetic storm in the current 24th solar cycle. A specific configuration of the Swarm satellites allowed investigation of the evolution of the storm-time ionospheric alterations on the day-and the nightside quasi-simultaneously. With the development of the main phase of the storm, a significant dayside increase of the vertical total electron content (VTEC) and electron density Ne was first observed at low latitudes on the dayside. From ~22 UT of 22 June to ~1 UT of 23 June, the dayside experienced a strong negative ionospheric storm, while on the nightside an extreme enhancement of the topside VTEC occurred at mid-latitudes of the northern hemisphere. Our analysis of the equatorial electrojet variations obtained from the magnetic Swarm data indicates that the storm-time penetration electric fields were, most likely, the main driver of the observed ionospheric effects at the initial phase of the storm and at the beginning of the main phase. The dayside ionosphere first responded to the occurrence of the strong eastward equatorial electric fields. Further, penetration of westward electric fields led to gradual but strong decrease of the plasma density on the dayside in the topside ionosphere. At this stage, the disturbance dynamo could have contributed as well. On the nightside, the observed extreme enhancement of the Ne and VTEC in the northern hemisphere (i.e., the summer hemisphere) in the topside ionosphere was most likely due to the combination of the prompt penetration electric fields, disturbance dynamo and the storm-time thermospheric circulation. From ~2.8 UT, the ionospheric measurements from the three Swarm satellites detected the beginning of the second positive storm on the dayside, which was not clearly associated with electrojet variations. We find that this second storm might be provoked by other drivers, such as an increase in the thermospheric composition.

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Section: Resultsmentioning

confidence: 66%

Prompt penetration electric fields and the extreme topside ionospheric response to the June 22–23, 2015 geomagnetic storm as seen by the Swarm constellation

2016

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“…Generally, the equatorial electric field perturbation after substorm onset could be either eastward or westward. Huang [] showed that the westward electric field perturbation is in many cases related to a northward turning of the interplanetary magnetic field (IMF), which often coincides with substorm onset. Huang [] also showed that the equatorial electric field perturbation after substorm onset is eastward when the IMF is continuously southward around the onset without a northward turning of the IMF.…”

Section: Resultsmentioning

confidence: 99%

The equatorial electrojet during geomagnetic storms and substorms

Yamazaki

Kosch

2015

JGR Space Physics

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The climatology of the equatorial electrojet during periods of enhanced geomagnetic activity is examined using long‐term records of ground‐based magnetometers in the Indian and Peruvian regions. Equatorial electrojet perturbations due to geomagnetic storms and substorms are evaluated using the disturbance storm time (Dst) index and auroral electrojet (AE) index, respectively. The response of the equatorial electrojet to rapid changes in the AE index indicates effects of both prompt penetration electric field and disturbance dynamo electric field, consistent with previous studies based on F region equatorial vertical plasma drift measurements at Jicamarca. The average response of the equatorial electrojet to geomagnetic storms (Dst<−50 nT) reveals persistent disturbances during the recovery phase, which can last for approximately 24 h after the Dst index reaches its minimum value. This “after‐storm” effect is found to depend on the magnitude of the storm, solar EUV activity, season, and longitude.

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“…Later, the onset of a substorm around 1725 UT caused another PPEF and resulted in rapid enhancement in the zonal electric field over Brazil which is termed as PPEF‐2 phase. The penetration of substorm‐induced electric fields from high latitudes to low latitudes is reported by several studies during other storm events [ Gonzales et al ., ; Kikuchi et al ., ; Sastri et al ., ; Huang , ]. It has been reported earlier that the zonal electric field disturbance is eastward during daytime at the low latitudes with the positive geomagnetic field disturbance under southward IMF Bz during the storm time substorm [ Huang et al ., and Huang , , ].…”

Section: Discussionmentioning

confidence: 97%

“…It has been reported earlier that the zonal electric field disturbance is eastward during daytime at the low latitudes with the positive geomagnetic field disturbance under southward IMF Bz during the storm time substorm [ Huang et al ., and Huang , , ]. Huang [, ] reported that the increased convection at substorm onset causes an enhanced magnetosphere electric field which penetrates into the dayside low‐latitude ionosphere resulting in an enhanced zonal electric field.…”

Section: Discussionmentioning

confidence: 99%

Electrodynamic disturbances in the Brazilian equatorial and low‐latitude ionosphere on St. Patrick's Day storm of 17 March 2015

et al. 2017

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The St. Patrick's Day storm of 17 March 2015 has a long‐lasting main phase with the Dst reaching a minimum of −223 nT. During the main phase, two strong prompt penetration electric field (PPEF) phases took place; first with the southward turning of IMF Bz around ~1200 UT and the second with the onset of a substorm around ~1725 UT leading to strong equatorial zonal electric field enhancements. The consequent spatiotemporal disturbances in the ionospheric total electron content and the resultant modifications in the equatorial ionization anomaly (EIA) over the Brazilian longitudinal sector are investigated in detail. The simultaneous measurements from a large network of GPS receivers, ionosonde, and magnetometers over the Brazilian longitudinal sector are used for this study. In the presence of enhanced zonal electric field, the equatorial F2 layer peak (hmF2) experienced a rapid uplift without any significant change in the base height (h′F); while the F2 layer is redistributed into F2 and F3 layers. The enhanced zonal electric filed due to PPEF led to the strong super fountain effect under which the anomaly crest departed poleward to ~40°S latitude. In the presence of westward and equatorward wind surge over Brazil with the coexisting disturbance dynamo fields, strong hemispheric asymmetry is seen in the storm time response of EIA during both the PPEF phases.

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Statistical analysis of dayside equatorial ionospheric electric fields and electrojet currents produced by magnetospheric substorms during sawtooth events

Cited by 33 publications

References 49 publications

Prompt penetration electric fields and the extreme topside ionospheric response to the June 22–23, 2015 geomagnetic storm as seen by the Swarm constellation

Prompt penetration electric fields and the extreme topside ionospheric response to the June 22–23, 2015 geomagnetic storm as seen by the Swarm constellation

The equatorial electrojet during geomagnetic storms and substorms

Electrodynamic disturbances in the Brazilian equatorial and low‐latitude ionosphere on St. Patrick's Day storm of 17 March 2015

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