Perturbation electric fields and disturbance currents investigated during the 25 September 1998 great storm

Horvath, Ildiko and Lovell, Brian C. (2014) Perturbation electric fields and disturbance currents investigated during the 25 September 1998 great storm. Journal of Geophysical Research-Space Physics, 119 10: 8483-8498. doi:10.1002/2014JA020480

Author Horvath, Ildiko
Lovell, Brian C.
Title Perturbation electric fields and disturbance currents investigated during the 25 September 1998 great storm
Journal name Journal of Geophysical Research-Space Physics   Check publisher's open access policy
ISSN 2169-9380
Publication date 2014-10
Year available 2014
Sub-type Article (original research)
DOI 10.1002/2014JA020480
Open Access Status
Volume 119
Issue 10
Start page 8483
End page 8498
Total pages 16
Place of publication Hoboken, NJ United States
Publisher Wiley-Blackwell Publishing
Collection year 2015
Language eng
Formatted abstract
This study investigates the ionosphere's response to the 25 September 1998 great storm and utilizes multi-instrument observations covering the Australian (140°E; geographic) and Indian (75°E) longitude sectors. Results show the domination of eastward (westward) electrojet at 140°E (75°E). Its causative net eastward (westward) perturbation electric (E) field drove the forward (reverse) plasma fountain, caused the presence (absence) of the equatorial ionization anomaly (EIA). These strong longitudinal differences were due to a combination of various LT-dependent, E field-driven, and competing mechanisms. Perturbation E fields are identified as prompt penetration E field (PPEF) and disturbance dynamo E field (DDEF). Due to the later (earlier) local time at 140°E (75°E), the undershielding PPEF was eastward (westward) directed early in the main phase. A series of periodic substorms occurred during the recovery phase. The substorm-related eastward PPEFs became overpowered by westward DDEFs over India but remained dominant in the Australian sector. Thus, eastward PPEFs (westward DDEFs) dominated at 140°E (75°E). At 140°E these eastward PPEFs exhibited a strong positive correlation with the variations of both the cross polar cap potential drop and the asymmetric ring current, significantly increased the net equatorial upward E × B drift and thus caused EIA development with plasma bubbles scintillating GPS signals. Based on the strong and independent correlation of these asymmetric ring current events with both the EIA development and the scintillation activity, we propose that the ASY-H index could provide a natural tool for modeling EIA development and scintillation episodes during severe storms characterized by periodic substorm-related eastward PPEFs.
Keyword Equatorial electrojet
Great storm
Periodic substorms
GPS signal scintillation
Partial Ring Current
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2015 Collection
School of Information Technology and Electrical Engineering Publications
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