Response of the equatorial ionosphere in the South Atlantic Region to the Great Magnetic Storm of July 15, 2000

Basu, Susanto; Groves, K. M.; Yeh, H.-C.; Su, S.‐Y.; Rich, F. J.; Sultan, P. J.; Keskinen, M. J.

doi:10.1029/2001gl013259

Cited by 208 publications

(215 citation statements)

References 15 publications

Supporting

Mentioning

195

Contrasting

Order By: Relevance

“…[23] Further, based on spaced-receiver scintillation observations and DMSP and ROCSAT ion drift measurements, it has been established that the penetration electric field is both eastward and northward at equatorial latitudes over the dusk sector [Basu et al, 2001a;Kelley et al, 2004]. As a result, the equatorial plasma is lifted up, diffuses north and south along magnetic field lines, and is then swept westward as a SED plume Vlasov et al, 2003;Kelley et al, 2004].…”

Section: Discussionmentioning

confidence: 99%

“…[24] While several superstorms have generated large storm-time perturbations in the SAMA region as discussed by Greenspan et al [1991] for the 13 October 1989 storm, Basu et al [2001a] for the Bastille Day storm, and the October-November 2003 storms discussed in this paper, the equatorial ionospheric perturbations, caused by the main phase of many other intense storms studied recently, have been at different longitudes depending on the UT of storm onset [Basu et al, 2001b[Basu et al, , 2005aMartinis et al, 2005]. Our objective has been to show that from knowledge of the UT variation of the D st index during the main phase of intense magnetic storms, it is possible to specify the longitude sector in the equatorial region where ionospheric disturbances in the form of plasma bubbles and bite-outs will occur.…”

Section: Discussionmentioning

confidence: 99%

“…Modeling the disturbance dynamo phase is complicated because the disturbance dynamo electric fields have to operate on an ionosphere that has been modified by the initial prompt penetration electric fields [Maruyama et al, 2005]. Our understanding of this complex interaction can be advanced by global ionospheric modeling of many storms and model validation with observations at globally dispersed locations [Fejer et al, 1990;Greenspan et al, 1991;Fejer and Scherliess, 1995;Fejer and Emmert, 2003;Basu et al, 2001aBasu et al, , 2001bBasu et al, , 2005aBasu et al, , 2005bMartinis et al, 2005].…”

Section: Introductionmentioning

confidence: 99%

“…[3] During the Bastille Day storm, an eastward penetration electric field between 2000 and 2100 universal time (UT) on 15 July 2000 associated with a sharp decrease in the SYM-H (1-min D st index) index lifted the ionosphere and formed plasma bubbles and bite-outs in the F region over the South Atlantic and Brazilian sectors where dusk conditions prevailed [Basu et al, 2001a]. At the same time, in the postmidnight sector, the penetration of a westward electric field caused the ionospheric F region over India to drift downward and collapse through recombination [Sastri et al, 2002].…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Response of the equatorial ionosphere at dusk to penetration electric fields during intense magnetic storms

et al. 2007

Self Cite

View full text Add to dashboard Cite

different aspects of which have been widely studied by the community. We present here a very complete set of space and ground-based diagnostics that provide the vertical and latitudinal structures of the ionosphere within the South Atlantic magnetic anomaly (SAMA) region and the contiguous parts of South America and Africa. We show that for both storms, the dusk sector corresponding to the universal time (UT) interval between the fast decrease of the SYM-H index and minimum SYM-H value determines uniquely the longitude interval populated by equatorial plasma bubbles and depletions. Further, we find that the UT of these storms is such that the ionospheric density perturbations occur in the SAMA region, which are most extended in latitude and altitude compared with other regions of the globe. In the dusk sector, the eastward penetration electric field, associated with rapid SYM-H decrease, adds to the postsunset eastward E-field because of the F region dynamo, which may be specially enhanced in this longitude interval because of the increased zonal conductivity gradient caused by energetic particle precipitation. This enhanced E-field at dusk causes a rapid uplift of the ionosphere and sets off plasma instabilities to form bubbles or bite-outs. The decreased ion density seen in the Defense Meteorological Satellite Program (DMSP) in situ data at 840 km indicates that the ionospheric plasma has been lifted above the DMSP altitude and transported away from the region by diffusion along magnetic field lines. Plasma bubbles and bite-outs impact satellite communication and navigation systems by introducing scintillations and steep density gradients. This paper corroborates that intense magnetic storms follow the framework, developed by Su. Basu et al. (2001) for moderate storms, that specifies the longitude interval in which such disturbances are most likely to occur.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Response of the equatorial ionosphere at dusk to penetration electric fields during intense magnetic storms

et al. 2007

Self Cite

View full text Add to dashboard Cite

show abstract

“…These observations are consistent with generation of scintillations in the main phase of the storm and a suppression of scintillations in the recovery phase. The scintillations in the pre-midnight period on 28 October are attributed to a prompt penetration of the magnetospheric electric field (Basu et al, 2001a, b), while the post-midnight scintillations are freshly generated irregularities caused by the disturbance dynamo electric field (Basu et al, 2001a;Bhattacharya et al, 2002). The magnetic storm of 5-9 August 1992 occurred at 14:30 LT on 5 August, with a minimum D st value of −80 nT and its K p index varied between 2 + to 6 − (Fig.…”

Section: Examples Of Category-imentioning

confidence: 99%

Effect of solar and magnetic activity on VHF scintillations near the equatorial anomaly crest

2004

View full text Add to dashboard Cite

Abstract. The VHF amplitude scintillation recorded during the period January 1991 to December 1993 in the declining phase of a solar cycle and April 1998 to December 1999 in the ascending phase of the next solar cycle at Varanasi (geogr. lat.=25.3 • , long. =83.0 • , dip=37 • N) have been analyzed to study the behavior of ionospheric irregularities during active solar periods and magnetic storms. It is shown that irregularities occur at arbitrary times and may last for <30 min. A rise in solar activity increases scintillations during winter (November-February) and near equinoxes (March-April; September-October), whereas it depresses the scintillations during the summer (May-July). In general, the role of magnetic activity is to suppress scintillations in the pre-midnight period and to increase it in the post-midnight period during equinox and winter seasons, whilst during summer months the effect is reversed. The pre-midnight scintillation is sometimes observed when the main phase of D st corresponds to the pre-midnight period. The annual variation shows suppression of scintillations on disturbed days, both during premidnight and post-midnight period, which becomes more effective during years of high solar activity. It is observed that for magnetic storms for which the recovery phase starts postmidnight, the probability of occurrence of irregularities is enhanced during this time. If the magnetic storm occurred during daytime, then the probability of occurrence of scintillations during the night hours is decreased. The penetration of magnetospheric electric fields to the magnetic equator affects the evolution of low-latitude irregularities. A delayed disturbance dynamo electric field also affects the development of irregularities.

show abstract

Equatorial westward electrojet impacting equatorial ionization anomaly development during the 6 April 2000 superstorm

Horvath

Lovell

2013

JGR Space Physics

View full text Add to dashboard Cite

[1] We investigate the forward plasma fountain and the equatorial ionosphere in the topside region during the 6 April 2000 superstorm in the Australian sector at~0900 LT. Space-and ground-based multi-instrument measurements, Coupled Thermosphere-IonospherePlasmasphere Electrodynamics (CTIPe) simulations, and field-aligned observations comprise our results. These reveal an unusual storm development during which the eastward prompt penetration electric (E) field (PPEF) developed and operated under the continuous effects of the westward disturbance dynamo E-field (DDEF) while large-scale traveling ionospheric disturbances (TIDs) traveled equatorward and generated strong equatorward wind surges. We have identified the eastward PPEF by the superfountain effect causing the equatorial ionization anomaly (EIA)'s development with crests situated at~±28°N (geomagnetic) in the topside ionosphere at~840 km altitude. The westward DDEF's occurrence is confirmed by mapping the "anti-Sq" current system wherein the equatorial westward current created a weak long-lasting westward electrojet event. Line plots of vertical drift data tracked large-scale TIDs. Four scenarios, covering~3.5 h in universal time, demonstrate that the westward DDEF became superimposed on the eastward PPEF. As these E-fields of different origins became mapped into the F region, they could interact. Consequently, the eastward PPEF-related equatorial upward E Â B drift became locally reduced by up to 75 m/s near the dip equator by the westward DDEF-related equatorial downward E Â B drift. Meanwhile, the EIA displayed a better development as equatorial wind surges, reproduced by CTIPe, increased from 501 to 629 m/s, demonstrating the crucial role of mechanical wind effects keeping plasma density high.

show abstract

Response of the equatorial ionosphere in the South Atlantic Region to the Great Magnetic Storm of July 15, 2000

Cited by 208 publications

References 15 publications

Response of the equatorial ionosphere at dusk to penetration electric fields during intense magnetic storms

Response of the equatorial ionosphere at dusk to penetration electric fields during intense magnetic storms

Effect of solar and magnetic activity on VHF scintillations near the equatorial anomaly crest

Equatorial westward electrojet impacting equatorial ionization anomaly development during the 6 April 2000 superstorm

Contact Info

Product

Resources

About