Observation of isolated high‐speed auroral streamers and their interpretation as optical signatures of Alfvén waves generated by bursty bulk flows

Liu, W. W.; Liang, J.; Donovan, E.; Trondsen, T.; Baker, G.; Sofko, G. J.; Jackel, B. J.; Wang, C.-P.; Mende, S. B.; Frey, H. U.; Angelopoulos, V.

doi:10.1029/2007gl032722

Cited by 10 publications

(18 citation statements)

References 14 publications

(18 reference statements)

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“…The auroral feature reported here moved westward and poleward first to be followed by an equatorward‐dawnward retreat. Just like the phenomenon by Liu et al [2008], this observation was revealed by the highly sensitive NORSTAR (NORthern Solar Terrestrial ARray) All‐Sky Imager at Rankin Inlet (72.41/335.74 geomag. lat./long.)…”

Section: Introductionmentioning

confidence: 57%

“…As discussed in the Introduction section, almost all previous reports of auroral streamers showed equatorward motion only [e.g., Rostoker et al , 1987; Henderson et al , 1998]. The only exception is the report by Liu et al [2008] who showed a low‐latitude poleward streamer moving poleward to meet a high‐latitude streamer moving equatorward. They associated both streamers with earthward flows in the magnetotail and attributed the poleward motion of the streamer to the propagation time delay of Alfvén waves from the source region to the ionosphere.…”

Section: Summary and Discussionmentioning

confidence: 98%

“…The only exception is a streamer reported by Liu et al [2008], who found a low‐latitude streamer moving poleward to meet a high‐latitude streamer moving equatorward on April 15, 2006. In this paper, we report observation of an auroral feature emerging from the poleward part of the auroral oval, distinctly different from the low‐latitude streamer reported by Liu et al [2008]. The auroral feature reported here moved westward and poleward first to be followed by an equatorward‐dawnward retreat.…”

Section: Introductionmentioning

confidence: 96%

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A transient narrow poleward extrusion from the diffuse aurora and the concurrent magnetotail activity

et al. 2010

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[1] We report observation of a transient narrow auroral feature extruding from the poleward boundary of the diffuse aurora on March 19, 2009. It moved westward and poleward initially to form part of a vortex pattern, followed by its equatorward-dawnward retreat later. During this auroral activity, THEMIS satellites, projected near the same magnetic local time of the auroral feature, detected appreciable plasma flows, increase in the ratio of the ion energy over the electron energy, and some enhancements of electrostatic waves. The plasma flows were initially duskward-earthward and changed to duskward-tailward later. The overall development of the observed plasma flow pattern was detected during the equatorward-dawnward retreat of the auroral feature when the Alfvén transit time between the magnetotail and the ionosphere is taken into account. This suggests that THEMIS satellites remotely sensed a counter-clockwise flow vortex (viewed from above the equatorial plane) in the magnetotail with decreasing strength. We suggest that the process generating the auroral feature is related to the flow vortex in association with the depletion of the electron energy relative to the ion energy and wave-particle interaction. An estimate of the possible associated current density is made. We provide reasoning for this auroral feature to be an auroral streamer and not a "failed" transpolar arc.

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Section: Introductionmentioning

confidence: 57%

Section: Summary and Discussionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 96%

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A transient narrow poleward extrusion from the diffuse aurora and the concurrent magnetotail activity

et al. 2010

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“…Although not reviewed here, because they lack observational confirmation, it is worth noting that other auroral features have been proposed to be caused by Alfvén waves. For example, Liu et al (2008) proposed that Alfvén waves generated by BBFs are the cause of auroral streamers.…”

Section: Location Of Alfvénic Auroramentioning

confidence: 99%

Alfvén Waves and Their Roles in the Dynamics of the Earth’s Magnetotail: A Review

2008

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The Earth's magnetotail is an extremely complex system which-energized by the solar wind-displays many phenomena, and Alfvén waves are essential to its dynamics. While Alfvén waves were first predicted in the early 1940's and ample observations were later made with rockets and low-altitude satellites, observational evidence of Alfvén waves in different regions of the extended magnetotail has been sparse until the beginning of the new millennium. Here I provide a phenomenological overview of Alfvén waves in the magnetotail organized by region-plasmasphere, central plasma sheet, plasma sheet boundary layer, tail lobes, and reconnection region-with an emphasis on spacecraft observations reported in the new millennium that have advanced our understanding concerning the roles of Alfvén waves in the dynamics of the magnetotail. A brief discussion of the coupling of magnetotail Alfvén waves and the low-altitude auroral zone is also included.

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“…Lyons et al (1999) claimed that PBIs are the result of the mapping to the ionosphere of the localized enhanced dawn-to-dusk electric fields that give rise to BBFs within the plasma sheet, as suggested by Henderson et al (1998). An observation of auroral streamers moving poleward at the same time that other auroral streamers moved equatorward from a PBI led Liu et al (2008) to propose a revised explanation. Alfvén waves generated by the BBFs were suggested to cause the auroral streamers.…”

Section: T Johansson Et Al: Electric Field Associated With a Bbf-limentioning

confidence: 99%

Observation of an inner magnetosphere electric field associated with a BBF-like flow and PBIs

et al. 2009

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Abstract. Themis E observed a perpendicular (to the magnetic field) electric field associated with an Earthward plasma flow at X GSM =−9.6 R E on 11 January 2008. The electric field observation resembles Cluster observations closer to Earth in the auroral region. The fast plasma flow shared some characteristics with bursty bulk flows (BBFs) but did not meet the usual criteria in maximum velocity and duration to qualify as one. Themis C observed the same flow further downtail but Themis D, separated by only 1 R E in azimuthal direction from Themis E, did not. At the time of the electric field and ion flow event, the all-sky imager and ground-based magnetometer at Rankin Inlet observed Poleward Boundary Intensifications (PBIs) and a negative bay signature. None of the other Themis ground-based observatories recorded any significant auroral or magnetic field activity, indicating that this was a localized activity. The joint Themis in situ and ground-based observations suggest that the two observations are related. This indicates that auroral electric fields can extend to regions much farther out than previously seen in Cluster observations.

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Observation of isolated high‐speed auroral streamers and their interpretation as optical signatures of Alfvén waves generated by bursty bulk flows

Cited by 10 publications

References 14 publications

A transient narrow poleward extrusion from the diffuse aurora and the concurrent magnetotail activity

A transient narrow poleward extrusion from the diffuse aurora and the concurrent magnetotail activity

Alfvén Waves and Their Roles in the Dynamics of the Earth’s Magnetotail: A Review

Observation of an inner magnetosphere electric field associated with a BBF-like flow and PBIs

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