Occurrence patterns for transient magnetic field signatures at high latitudes

Sibeck, D. G.; Korotova, G. I.

doi:10.1029/96ja00187

Cited by 56 publications

(82 citation statements)

References 72 publications

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“…However, none of the pressure variations excited a significant response at the location of GOES-8, deep within the dawn mag- Roelof and Sibeck, 1993]. It may also help explain why it is a simple matter to associate TCVs in high-latitude ground magnetograms with SI signatures at low latitudes and geosynchronous orbit [e.g., Sibeck, 1993], but it is rather more difficult to find a corresponding pressure change in the undisturbed solar wind [Sibeck and Korotova, 1996]. Apparently, the effects of the solar wind interaction with the bow shock are far more dynamic than was previously imagined.…”

Section: Discussionmentioning

confidence: 99%

Comprehensive study of the magnetospheric response to a hot flow anomaly

Sibeck¹,

Бородкова²,

Schwartz³

et al. 1999

J. Geophys. Res.

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Abstract. We present a comprehensive observational study of the magnetospheric response to an interplanetary magnetic field (IMF) tangential discontinuity, which first struck the postnoon bow shock and magnetopause and then swept past the prenoon bow shock and magnetopause on July 24, 1996. Although unaccompanied by any significant plasma variation, the discontinuity interacted with the bow shock to form a hot flow anomaly (HFA), which was observed by Interball-1 just upstream from the prenoon bow shock. Pressures within and Earthward of the HFA were depressed by an order of magnitude, which allowed the magnetopause to briefly (-7 min) move outward some 5 R E beyond its nominal position and engulf Interball-1.A timing study employing nearby Interball-1 and Magion-4 observations demonstrates that this motion corresponded to an antisunward and northward moving wave on the magnetopause. The same wave then engulfed Geotail, which was nominally located downstream in the outer dawn magnetosheath. Despite its large amplitude, the wave produced only minor effects in GOES-8 geosynchronous observations near local dawn. Polar Ultraviolet Imager (UVI) observed a sudden brightening of the afternoon aurora, followed by an even more intense transient brightening of the morning aurora. Consistent with this asymmetry, the discontinuity produced only weak near-simultaneous perturbations in highlatitude postnoon ground magnetometers but a transient convection vortex in the prenoon Greenland ground magnetograms. The results of this study indicate that the solar wind interaction with the bow shock is far more dynamic than previously imagined and far more significant to the solar wind-magnetosphere interaction.

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Section: Discussionmentioning

confidence: 99%

Comprehensive study of the magnetospheric response to a hot flow anomaly

Sibeck¹,

Бородкова²,

Schwartz³

et al. 1999

J. Geophys. Res.

Self Cite

189

226

View full text Add to dashboard Cite

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“…Several statistical studies have partially addressed the second prediction. Glaßmeier et al (1989), Lanzerotti et al (1991), and Sibeck and Korotova (1996) all reported a strong tendency for transient events in the high-latitude dayside ionosphere to occur prior to local noon, as might be expected for the prevailing spiral IMF orientation. No statistical survey has addressed the third prediction.…”

Section: Introductionmentioning

confidence: 99%

“…Konik et al (1994) and Sibeck and Korotova (1996) reported that transient events observed in the high-latitude dayside ionosphere exhibit only a slight tendency to occur for northward IMF orientations. Rather than providing information about their generation mechanism, this tendency may simply reflect difficulties in identifying the relatively lowamplitude events during the periods of intense geomagnetic activity that are expected for southward IMF orientations.…”

Section: Introductionmentioning

confidence: 99%

Interplanetary magnetic field control of dayside transient event occurrence and motion in the ionosphere and magnetosphere

et al. 2004

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Abstract. The pressure pulse model for dayside transient ionospheric events predicts dawnward moving events at and prior to local noon during periods of spiral interplanetary magnetic field (IMF) orientation, but duskward moving events at and after local noon during rarer periods of orthospiral IMF orientation. We use this model to interpret ground and geosynchronous magnetometer observations of a duskward-moving transient event that occurred on 10 August 1995 during a period of orthospiral IMF orientation. We then survey geosynchronous GOES-8, 9, and 10 magnetometer observations to determine the directions of motion for 67 isolated magnetic impulse events seen in South Pole magnetograms from 1995-1999. The occurrence patterns and directions of motion inferred from both case and statistical studies are consistent with pressure pulse model predictions.

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“…Konik et al [1994] found that only 15-30% of their studied events could be associated with dynamic pressure variations in the solar wind, while 70% or more were the result of localized reconnection. Sibeck and Korotova [1996] reported that the majority of the impulsive events that they studied were associated with sharp changes in the IMF orientation, but only a few could be associated with changes in the solar wind dynamic pressure. Sitar et al…”

Section: Introductionmentioning

confidence: 99%

“…Ground magnetometers in the high-latitude dayside region regularly observe a variety of pulsations and transient signatures. Sibeck and Korotova, 1996]. However, evidence has been insufficient to conclusively connect any one of these processes with ground signatures.…”

Section: Introductionmentioning

confidence: 99%

The November 9, 1993, traveling convection vortex event: A case study

Zesta¹,

Hughes²,

Engebretson³

et al. 1999

J. Geophys. Res.

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Abstract. On November 9, 1993, at around 1715 UT, a strong and well-structured traveling convection vortex (TCV) event occurred and was observed by the Magnetometer Array for Cusp and Cleft Studies (MACCS) and the Canadian Auroral Network for the OPEN Program Unified Study (CANOPUS) magnetometer chains. The Greenland chain, which is located farther to the east, observed only a very weak signature for the same event. We studied the propagation characteristics of the two-dimensional vortical TCV current patterns. The TCV event is a series of four vortical currents propagating westward. We found that individual vortices propagate with different speeds. The vortices are created in the early postnoon region. They accelerate as they strengthen, and some decelerate, weaken, and disappear within the 6 hours of magnetic local time of the field of view of the ground magnetometers. The strongest, main vortex of the event accelerates until it moves out of the field of view and, more than likely, reaches well into the nightside. We studied the correlated solar wind and IMF signatures as observed by the IMP 8 spacecraft, sitting in the far dawnside and outside the bow shock. We found that the transient currents in the ionosphere are the result of sharp, short-lived pressure pulses hitting the magnetopause during times of quiet and northward IMF that is primarily radial. We find that the pressure pulses are more than likely created just upstream of the bow shock by the interaction of the quasi-parallel shock with IMF orientation changes and are not intrinsic features of the upstream solar wind. We also analyze the transient signatures in the inner magnetosphere by studying the magnetic field data in the GOES 6 and 7 satellites. We suggest that a series of five successive compression and depression peaks in the GOES magnetic field data are well correlated with the set of solar wind pressure pulses. We observe a propagation velocity of the transient event from the GOES 6 spacecraft to the GOES 7 spacecraft that agrees well with the propagation velocities that we calculate from the ground magnetometer stations.

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Occurrence patterns for transient magnetic field signatures at high latitudes

Cited by 56 publications

References 72 publications

Comprehensive study of the magnetospheric response to a hot flow anomaly

Comprehensive study of the magnetospheric response to a hot flow anomaly

Interplanetary magnetic field control of dayside transient event occurrence and motion in the ionosphere and magnetosphere

The November 9, 1993, traveling convection vortex event: A case study

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