Ionospheric disturbances observed by DMSP at middle to low latitudes during the magnetic storm of June 4–6, 1991

Burke, William J.; Rubin, A. G.; Maynard, N. C.; Gentile, L. C.; Sultan, P. J.; Rich, F. J.; Beaujardière, O. de La; Huang, Chao‐Song; Wilson, G. R.

doi:10.1029/1999ja000188

Cited by 83 publications

(112 citation statements)

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“…This is in agreement with earlier findings, such as by Spiro et al (1979), Anderson et al (1991), Karlsson et al (1998), Burke et al (2000), Anderson et al (2001), and with the model predictions presented by Southwood and Wolf (1978). According to their model, SAID events would occur predominantly in the premidnight sector, where the inner edge of the proton ring current extends earthward of the inner edge of the electron ring current.…”

Section: Discussionsupporting

confidence: 82%

“…Although different measurement techniques and different definitions were used, there are several features of this phenomenon generally agreed upon. The SAID phenomenon is a manifestation of magnetosphere-ionosphere coupling outside of the auroral region, characterized by westward ion drifts with velocities greater than 1000 m/s by many of the authors (Anderson et al, 1991;Galperin et al, 1997;Burke et al, 2000). Some authors have focused on the corresponding intense poleward-directed electric fields, reporting events with intensities greater than approximately 30 mV/m (Smiddy et al, 1977;Maynard, 1978;Maynard et al, 1980;Rich et al, 1980;Karlsson et al, 1998).…”

Section: Introductionmentioning

confidence: 99%

“…Some authors have focused on the corresponding intense poleward-directed electric fields, reporting events with intensities greater than approximately 30 mV/m (Smiddy et al, 1977;Maynard, 1978;Maynard et al, 1980;Rich et al, 1980;Karlsson et al, 1998). SAID structures are confined to latitudinally narrow regions (0.1 • -2 • CGLatCorrected Geomagnetic Latitude), equatorwards of the auroral zone (Karlsson et al, 1998;Galperin et al, 1997;Anderson et al, 2001), occur predominantly in the premidnight MLT (Magnetic Local Time) sector (18:00-02:00 MLT, S. Figueiredo et al: Investigation of subauroral ion drifts according to Spiro et al (1979), Karlsson et al (1998) and Anderson et al (2001)) and are substorm related (Smiddy et al, 1977;Maynard, 1978;Spiro et al, 1979;Maynard et al, 1980;Rich et al, 1980;Anderson et al, 1993;Karlsson et al, 1998;Keyser et al, 1998;Keyser, 1999;Burke et al, 2000;Anderson et al, 2001;Galperin, 2002).…”

Section: Introductionmentioning

confidence: 99%

“…Burke et al (2000) described the development of storm-driven SAID structures generated during the magnetic storm of 4-6 June 1991. The use of multisatellite (DMSP F8, F9, F10) measurements allowed for the analysis of conjugate SAID structures.…”

Section: Introductionmentioning

confidence: 99%

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Investigation of subauroral ion drifts and related field-aligned currents and ionospheric Pedersen conductivity distribution

2004

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Abstract. Based on Astrid-2 satellite data, results are presented from a statistical study on subauroral ion drift (SAID) occurrence. SAID is a subauroral phenomenon characterized by a westward ionospheric ion drift with velocity greater than 1000 m/s, or equivalently, by a poleward-directed electric field with intensity greater than 30 mV/m. SAID events occur predominantly in the premidnight sector, with a maximum probability located within the 20:00 to 23:00 MLT sector, where the most rapid SAID events are also found. They are substorm related, and show first an increase in intensity and a decrease in latitudinal width during the expansion phase, followed by a weakening and widening of the SAID structures during the recovery phase. The potential drop across a SAID structure is seen to remain roughly constant during the recovery phase.The field-aligned current density and the height-integrated Pedersen conductivity distribution associated with the SAID events were calculated. The results reveal that the strongest SAID electric field peaks are associated with the lowest Pedersen conductivity minimum values. Clear modifications are seen in the ionospheric Pedersen conductivity distribution associated with the SAID structure as time evolves: the SAID peak is located on the poleward side of the corresponding region of reduced Pedersen conductivity; the shape of the regions of reduced conductivity is asymmetric, with a steeper poleward edge and a more rounded equatorward edge; the SAID structure becomes less intense and widens with evolution of the substorm recovery phase. From the analysis of the SAID occurrence relative to the mid-latitude trough position, SAID peaks are seen to occur relatively close to the corresponding mid-latitude trough minimum. Both these features show a similar response to magnetospheric disturbances, but on different time scales -with increasing magnetic activity, the SAID structure shows a faster movement towards lower latitudes than that of the mid-latitude trough.From the combined analysis of these results, we conclude that the SAID generation mechanism cannot be regarded ei- ther as a pure voltage generator or as a pure current generator, applied to the ionosphere. While the anti-correlation between the width and the peak intensity of the SAID structures with substorm evolution indicates a magnetospheric source acting as a constant voltage generator, the ionospheric modifications and, in particular the reduction in the conductivity for intense SAID structures, are indicative of a constant current system closing through the ionosphere. The ionospheric feedback mechanisms are seen to be of major importance for sustaining and regulating the SAID structures.

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Section: Discussionsupporting

confidence: 82%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Investigation of subauroral ion drifts and related field-aligned currents and ionospheric Pedersen conductivity distribution

2004

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“…Weak eastward eletrojets (negative) are found equatorward of the dominant westward electrojet (positive) on the nightside after 05:00 UT, which are thought to be associated with the sub-auroral polarization stream (SAPS). Burke et al (2000) reported also observations of SAPS appearing continuously during the ring current buildup associated with the main phase of a geomagnetic storm. The model cannot reproduce the SAPS features.…”

Section: Instrumentation and Data Processingmentioning

confidence: 96%

Storm time dynamics of auroral electrojets: CHAMP observation and the Space Weather Modeling Framework comparison

et al. 2008

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Abstract. We investigate variations of the location and intensity of auroral currents during two magnetic storm periods based on magnetic field measurements from CHAMP separately for both hemispheres, as well as for the dayside and nightside. The corresponding auroral electrojet current densities are on average enhanced by about a factor of 7 compared to the quiet time current strengths. The nightside westward current densities are on average 1.8 (2.2) times larger than the dayside eastward current densities in the Northern (Southern) Hemisphere. Both eastward and westward currents are present during the storm periods with the most intense electrojets appearing during the main phase of the storm, before the ring current maximizes in strength. The eastward and westward electrojet centers can expand to 55 • MLat during intense storms, as is observed on 31 March 2001 with D st =−387 nT. The equatorward shift of auroral currents on the dayside is closely controlled by the southward IMF, while the latitudinal variations on the nightside are better described by the variations of the D st index. However, the equatorward and poleward motion of the nightside auroral currents occur earlier than the D st variations. The Space Weather Modeling Framework (SWMF) can capture the general dynamics of the storm time current variations. Both the model and the actual data show that the currents tend to saturate when the merging electric field is larger than 10 mV/m. However, the exact prediction of the temporal development of the currents is still not satisfactory.

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Equatorial broad plasma depletions associated with the enhanced fountain effect

et al. 2014

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[1] Broad plasma depletions (BPDs), plasma depletions whose longitudinal width is over several hundred kilometers, have been detected in the equatorial F region by low-earth-orbit satellites during both magnetically quiet and magnetically disturbed periods. A few hypotheses were suggested to explain the creation of BPDs, but the underlying mechanism of this phenomenon is still under debate. We investigate the origin of BPDs by analyzing the simultaneous in situ and optical observations of the ionosphere on 30 May 2003 (Kp = 8 + ), 24 April 2012 (Kp = 7 À ), and 31 October 2012 (Kp = 0 + ). BPDs on 30 May 2003 were detected by the Republic of China Satellite-1 at an altitude of 600 km, and BPDs on the other days were detected by the Communication/Navigation Outage Forecasting System satellite near an altitude of 400 km. Our results show that the detection of BPDs is closely associated with background ionospheric morphology; BPDs are detected on the days when the equatorial ionization anomaly (EIA) is intense and the crests of the EIA have moved poleward. Measurements of upward plasma motion support the existence of ionospheric uplift at BPD locations. These observations and the detection of BPDs near the magnetic equator lead to the interpretation that the satellite detection of BPDs during those 3 days is likely related to the uplift of the F peak height above the satellite orbits.

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Ionospheric disturbances observed by DMSP at middle to low latitudes during the magnetic storm of June 4–6, 1991

Abstract: Abstract.This paper extends a recent study of eleclric field penetration into the inner magnetosphere observed by the Colnbined Release and Radiation Effects

Cited by 83 publications

References 40 publications

Investigation of subauroral ion drifts and related field-aligned currents and ionospheric Pedersen conductivity distribution

Investigation of subauroral ion drifts and related field-aligned currents and ionospheric Pedersen conductivity distribution

Storm time dynamics of auroral electrojets: CHAMP observation and the Space Weather Modeling Framework comparison

Equatorial broad plasma depletions associated with the enhanced fountain effect

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