Ionospheric effects of major magnetic storms during the International Space Weather Period of September and October 1999: GPS observations, VHF/UHF scintillations, and in situ density structures at middle and equatorial latitudes
Sunanda Basu,Santimay Basu,Cesar E. Valladares,H.-C. Yeh,S.-Y. Su,E. MacKenzie,P. J. Sultan,Jules Aarons,Frederick J. Rich,Patricia H. Doherty,Keith M. Groves,Terence Bullett +11 more
TLDR
In this article, the ionospheric effects of a halo coronal mass ejection (CME) initiated on the Sun on September 20, 1999, and causing the largest magnetic storm during this month on September 22, 23, and 24, 1999 were studied through their effects on a prototype of a Global Positioning System (GPS)-based navigation system called Wide Area Augmentation System (WAAS) and their impact on global VHF/UHF communication systems.Abstract:
In this paper we present a study of the ionospheric effects of a halo coronal mass ejection (CME) initiated on the Sun on September 20, 1999, and causing the largest magnetic storm during this month on September 22–23, 1999, with the hourly Dst index being −167 nT at ∼2400 UT on September 22. The recurrent CME on October 18 caused an even larger magnetic storm on October 22, 1999, with Dst of −231 nT at ∼0700 UT. The ionospheric effects of these two major magnetic storms are studied through their effects on a prototype of a Global Positioning System (GPS)-based navigation system called Wide Area Augmentation System (WAAS) being developed by the Federal Aviation Administration for use in the continental United States and their impact on global VHF/UHF communication systems. It is shown that the penetration of transient magnetospheric electric fields equatorward of the shielding region at midlatitudes, which have been well-correlated in the past with rapid changes in the well-known Dst index (or through its recently available high resolution 1-min counterpart the SYM-H index), can cause large increases of total electron content (TEC), TEC fluctuations, and saturated 250-MHz scintillation, and these, in turn, may have significant impacts on WAAS. The local time of Dst changes (and not just Dst magnitude) was found to be very important for WAAS, since the largest effects on TEC are seen near dusk. The prompt penetration of these magnetospheric electric fields all the way to the magnetic equator causes augmentation or inhibition of equatorial spread F. The global ionospheric response to these storms has been obtained from ground-based TEC observations with a GPS network and space-based in situ density and electric field measurements using the Republic of China Satellite-1 (ROCSAT-I) and several Defense Meteorological Satellite Program satellites. These prompt penetration electric fields cause VHF/UHF scintillations and GPS TEC variations at low latitudes in the specific longitude sector for which the early evening period corresponds to the time of rapid Dst variations and maximum Dst phase. The effects of the delayed ionospheric disturbance dynamo and those of decreased magnetospheric convection on postmidnight irregularity generation are shown to be confined to a part of the same longitude range that actively responded to the prompt penetration of electric fields in the early evening sector.read more
Citations
More filters
Journal ArticleDOI
GPS and ionospheric scintillations
TL;DR: In this paper, the authors review the impact of scintillations on GPS receiver design and use and present a review of GPS and ionospheric scintillation for scientists interested in space weather.
Journal Article
Penetration of high latitude electric fields effects tolow latitude during Sundial 1984
TL;DR: In this article, electric field penetration events were identified using F-region vertical-drift measurements obtained in the October 6-13, 1984 period by Jicamarcan incoherent-backscatter radar and corresponding h-prime F measurements from ionosondes at Fortaleza, Cachoeira Paulista, and Dakar.
Journal ArticleDOI
C/NOFS: a Mission to Forecast Scintillations
TL;DR: The communication/navigation outage forecasting system (C/NOFS) mission of the Air Force Research Laboratory as discussed by the authors is the first satellite solely dedicated to forecasting ionospheric irregularities and radio wave scintillations.
Journal ArticleDOI
TEC variations during low solar activity period (2005–2007) near the Equatorial Ionospheric Anomaly Crest region in India
TL;DR: In this paper, the authors analyzed the ionospheric variations in terms of Total Electron Content (TEC) for the low solar activity period from April 2005 to December 2007, and found that TEC at Rajkot is at its maximum during Equinoctial months (March, April, September, October), and minimum during the Winter months (November, December, January, February), with intermediate values during Summer months (May, June, July, August), showing a semi annual variation.
Journal ArticleDOI
Response of the equatorial ionosphere in the South Atlantic Region to the Great Magnetic Storm of July 15, 2000
S. Basu,Su. Basu,Keith M. Groves,H.-C. Yeh,S.-Y. Su,Frederick J. Rich,P. J. Sultan,M. J. Keskinen +7 more
TL;DR: The effects of the great magnetic storm of July 15, 2000 on the equatorial ionosphere have been studied by ground-based and satellite in-situ measurements as mentioned in this paper, showing that the IMF Bz turned southward and presumably caused penetration of E-fields to low latitudes, which initiated the onset of 250 MHz and L-band scintillations at Ascension Island (15°W).
References
More filters
Journal ArticleDOI
The ionospheric disturbance dynamo
M. Blanc,Arthur D. Richmond +1 more
TL;DR: In this article, a numerical simulation study of the thermospheric winds produced by auroral heating during magnetic storms, and of their global dynamo effects, establishes the main features of the ionospheric disturbance dynamo.
Journal ArticleDOI
Ionospheric Storms — A Review
TL;DR: In this paper, the authors reviewed the current understanding and recent advances in the study of ionospheric storms with emphasis on the F2-region, and proposed a global first principle physical model to simulate the storm response of the coupled neutral and ionized upper atmospheric constituents.
Journal ArticleDOI
Monitoring of global ionospheric irregularities using the Worldwide GPS Network
TL;DR: In this article, a prototype system has been developed to monitor the instantaneous global distribution of ionospheric irregularities, using the worldwide network of Globa Positioning System (GPS) receivers.
Journal ArticleDOI
Effects of the vertical plasma drift velocity on the generation and evolution of equatorial spread F
TL;DR: In this paper, the authors used radar observations from the Jicamarca Observatory from 1968 to 1992 to study the effects of the F region vertical plasma drift velocity on the generation and evolution of equatorial spread F.
Related Papers (5)
Empirical models of storm time equatorial zonal electric fields
Bela G. Fejer,Ludger Scherliess +1 more
Storm time dependence of equatorial disturbance dynamo zonal electric fields
Ludger Scherliess,Bela G. Fejer +1 more