Are earthward bursty bulk flows convective or field‐aligned?

Petrukovich, A. A.; Baumjohann, W.; Nakamura, R.; Schödel, R.; Mukai, T.

doi:10.1029/2001ja900019

Cited by 33 publications

(31 citation statements)

References 24 publications

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“…Depending on which plasma sheet regime is under consideration (CPS or PSBL), the axis orientation should vary between (quasi-) perpendicular and (quasi-) parallel to the magnetic field. The BBFs are dominantly (quasi-) perpendicular to the magnetic field in the CPS [Angelopoulos et al, 1994], and they are likely to extend into field-aligned beams in the PSBL [Nakamura et al, 1992;Petrukovich et al, 2001].…”

Section: Ecr Scale Sizementioning

confidence: 99%

“…In the CPS, the high-speed flows are generally bulk flows which are (quasi-) perpendicular to the ambient magnetic field, with GSM V x being the dominant velocity component, and V y occasionally substantial [Angelopoulos et al, 1994]. In the PSBL, on the other hand, the high-speed flows can usually be characterized as field-aligned beams [Nakamura et al, 1992;Petrukovich et al, 2001].…”

Section: Introductionmentioning

confidence: 99%

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Energy conversion regions as observed by Cluster in the plasma sheet

et al. 2011

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[1] In this article we present a review of recent studies of observations of localized energy conversion regions (ECRs) observed by Cluster in the plasma sheet at altitudes of 15-20R E . By examining variations in the power density, E · J, where E is the electric field and J is the current density, we show that the plasma sheet exhibits a high level of fine structure. Approximately three times as many concentrated load regions (CLRs) (E · J > 0) as concentrated generator regions (CGRs) (E · J < 0) are identified, confirming the average load character of the plasma sheet. Some ECRs are found to relate to auroral activity. While ECRs are relevant for the energy conversion between the electromagnetic field and the particles, bursty bulk flows (BBFs) play a central role for the energy transfer in the plasma sheet. We show that ECRs and BBFs are likely to be related, although details of this relationship are yet to be explored. The plasma sheet energy conversion increases rather simultaneously with increasing geomagnetic activity in both CLRs and CGRs. Consistent with large-scale magnetotail simulations, most of the observed ECRs appear to be rather stationary in space but varying in time. We estimate that the ECR lifetime and scale size are a few minutes and a few R E , respectively. It is conceivable that ECRs rise and vanish locally in significant regions of the plasma sheet, possibly oscillating between load and generator character, while some energy is transmitted as Poynting flux to the ionosphere.

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Section: Ecr Scale Sizementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Energy conversion regions as observed by Cluster in the plasma sheet

et al. 2011

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“…They tend to occur more frequently during active times but can occur also in the absence of substorms. The flows occur both in the high-beta central plasma sheet (beta is the ratio of plasma pressure over magnetic pressure), where they have a significant component perpendicular to the magnetic field, and in the low-beta plasma sheet boundary layer, where they are strongly field-aligned [e.g., Petrukovich et al, 2001]. These occurrences may be related to different activity phases, for instance, substorm expansion versus recovery.…”

Section: Introductionmentioning

confidence: 99%

“…[2] Satellite observations in the magnetotail [e.g., Baumjohann et al, 1990;Angelopoulos et al, 1992Angelopoulos et al, , 1994Sergeev et al, 1996;Schödel et al, 2001aSchödel et al, , 2001bPetrukovich et al, 2001] have demonstrated that the major transport of mass, energy, and magnetic flux in the plasma sheet occurs in a bursty fashion, associated with "bursty bulk flows" (BBFs). BBFs in the plasma sheet are fast flows (several hundreds of kilometers per second) of typically 10 minutes' total duration with individual peaks of the order of 1 minute [Angelopoulos et al, 1992].…”

Section: Introductionmentioning

confidence: 99%

Bursty bulk flows and dipolarization in MHD simulations of magnetotail reconnection

et al. 2011

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[1] Using three-dimensional MHD simulations of magnetic reconnection in the magnetotail, we investigate the fate of earthward bursty bulk flows (BBFs). The flow bursts are identified as entropy-depleted magnetic flux tubes ("bubbles") generated by the severance of a plasmoid via magnetic reconnection. The onset of fast reconnection coincides closely with a drastic entropy reduction at the onset of lobe reconnection. The fact that, in the simulation, the Alfvén speed does not change significantly at this time suggests that the destabilization of ballooning/interchange modes is important in driving faster reconnection as well as in providing cross-tail structure. In the initial phase, the BBFs are associated with earthward propagating dipolarization fronts. When the flow is stopped nearer to Earth, the region of dipolarization expands both azimuthally and tailward. Tailward flows are found to be associated with a rebound of the earthward flow and with reversed vortices on the outside of the flow. Earthward and tailward flows are also associated with expansion and contraction of the near plasma sheet. All of these features are consistent with recent satellite observations by Cluster and the Time History of Events and their Macroscopic Interactions during Substorms (THEMIS) mission.Citation: Birn, J., R. Nakamura, E. V. Panov, and M. Hesse (2011), Bursty bulk flows and dipolarization in MHD simulations of magnetotail reconnection,

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“…The observed fast flow in this event is perpendicular to the magnetic field. Fast flows can be both parallel and perpendicular to the magnetic field (Petrukoviclh et al, 2001;Raj et al, 2002). Perpendicular flows are typically found in high-β plasma, while parallel flows are found in low-β plasma.…”

Section: Discussionmentioning

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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Are earthward bursty bulk flows convective or field‐aligned?

Cited by 33 publications

References 24 publications

Energy conversion regions as observed by Cluster in the plasma sheet

Energy conversion regions as observed by Cluster in the plasma sheet

Bursty bulk flows and dipolarization in MHD simulations of magnetotail reconnection

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

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