Flux transport, dipolarization, and current sheet evolution during a double-onset substorm

Nakamura, R.; Baumjohann, W.; Panov, E. V.; Петрукович, А. А.; Angelopoulos, V.; Volwerk, M.; Magnes, W.; Nishimura, Y.; Runov, A.; Russell, C. T.; Weygand, J. M.; Amm, O.; Auster, H. U.; Bonnell, J. W.; Frey, H. U.; Larson, D. E.; McFadden, J. P.

doi:10.1029/2010ja015865

Cited by 37 publications

(45 citation statements)

References 66 publications

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“…Alternately, the tearing instability may be initiated by the negative ∂ B Z /∂ X [ Sitnov and Schindler , 2010]. The possibility of normal reconnection after some reconnection‐preconditioning process was considered, by, e.g., Nakamura et al [2011]. They suggested that a preceding reconnection took the magnetic flux away and created a second diffusion region, provoking another reconnection.…”

Section: Summary and Discussionmentioning

confidence: 99%

Kinetic ballooning/interchange instability in a bent plasma sheet

Panov¹,

Nakamura²,

Baumjohann³

et al. 2012

J. Geophys. Res.

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[1] We use Time History of Events and Macroscale Interactions during Substorms (THEMIS) and GOES observations to investigate the plasma sheet evolution on 28 February 2008 between 6:50 and 7:50 UT, when there developed strong magnetic field oscillations with periods of 100 s. Using multispacecraft analysis of the plasma sheet observations and an empirical plasma sheet model, we determine both the large-scale evolution of the plasma sheet and the properties of the oscillations. We found that the oscillations exhibited signatures of kinetic ballooning/interchange instability fingers that developed in a bent current sheet. The interchange oscillations had a sausage structure, propagated duskward at a velocity of about 100 km/s, and were associated with fast radial electron flows. We suggest that the observed negative gradient of the Z GSM magnetic field component (∂B Z /∂X) was a free energy source for the kinetic ballooning/interchange instability. Tens of minutes later a fast elongation of ballooning/interchange fingers was detected between 6 and 16 R E downtail with the length-to-width ratio exceeding 20. The finger elongation ended with signatures of reconnection in an embedded current sheet near the bending point. These observations suggest a complex interplay between the midtail and near-Earth plasma sheet dynamics, involving localized fluctuations in both cross-tail and radial directions before current sheet reconnection.

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Section: Summary and Discussionmentioning

confidence: 99%

Kinetic ballooning/interchange instability in a bent plasma sheet

Panov¹,

Nakamura²,

Baumjohann³

et al. 2012

J. Geophys. Res.

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“…Such structure, widely believed as a consequence of magnetic reconnection (Birn et al, ; Fu, Khotyaintsev, et al, ), can propagate both earthward and tailward (Angelopoulos et al, ; Fu, Cao, et al, ; Ohtani et al, ). The earthward BBF transports a large amount of mass and magnetic fluxes toward the Earth and subsequently triggers the substorm activity (e.g., Angelopoulos et al, ; Cao et al, ; Ergun et al, ; Fu et al, ; J. Liu et al, ; Ma et al, ; Nakamura et al, ; Panov et al, ; Sergeev et al, ; Xu, Fu, Norgren, et al, ; Yu et al, ).…”

Section: Introductionmentioning

confidence: 99%

Electron‐Driven Dissipation in a Tailward Flow Burst

Chen

Liu

et al. 2019

Geophysical Research Letters

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Traditionally, the magnetotail flow burst outside the diffusion region is known to carry ions and electrons together (Vi = Ve), with the frozen‐in condition well satisfied (E + Ve × B = 0). Such picture, however, may not be true, based on our analyses of the high‐resolution MMS (Magnetospheric Multiscale mission) data. We find that inside the flow burst the electrons and ions can be decoupled (Ve ≠ Vi), with the electron speed 5 times larger than the ion speed. Such super‐Alfvenic electron jet, having scale of 10 di (ion inertial length) in XGSM direction, is associated with electron demagnetization (E + Ve × B ≠ 0), electron agyrotropy (crescent distribution), and O‐line magnetic topology but not associated with the flow reversal and X‐line topology; it can cause strong energy dissipation and electron heating. We quantitatively analyze the dissipation and find that it is primarily attributed to lower hybrid drift waves. These results emphasize the non‐MHD (magnetohydrodynamics) behaviors of magnetotail flow bursts and the role of lower hybrid drift waves in dissipating energies.

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“…The dipolarization front (DF) is frequently observed [ Nakamura et al , 2002; Runov et al , 2009; Fu et al , 2011a; Schmid et al , 2011] in the Earth's magnetotail associated with the bursty bulk flow (BBF) [ Angelopoulos et al , 1992]. It receives much attention recently due to its important role in the flux transport event [e.g., Volwerk et al , 2008; Nakamura et al , 2009, 2011; Birn et al , 2011]. Both simulations [e.g., Sitnov et al , 2009; Sitnov and Swisdak , 2011; Birn et al , 2011; Wu and Shay , 2012] and observations [e.g., Runov et al , 2012] suggested that the DF can be produced by magnetic reconnection.…”

Section: Introductionmentioning

confidence: 99%

Pitch angle distribution of suprathermal electrons behind dipolarization fronts: A statistical overview

Fu¹,

Khotyaintsev²,

Vaivads³

et al. 2012

J. Geophys. Res.

146

201

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We examine the pitch angle distribution (PAD) of suprathermal electrons (>40 keV) inside the flux pileup regions (FPRs) that are located behind the dipolarization fronts (DFs), in order to better understand the particle energization mechanisms operating therein. The 303 earthward‐propagating DFs observed during 9 years (2001–2009) by Cluster 1 have been analyzed and divided into two groups according to the differential fluxes of the >40 keV electrons inside the FPR. One group, characterized by the low flux (F < 500/cm2 · s · sr · keV), consists of 153 events and corresponds to a broad distribution of IMF Bz components. The other group, characterized by the high flux (F ≥ 500/cm2 · s · sr · keV), consists of 150 events and corresponds to southward IMF Bzcomponents. Only the high‐flux group is considered to investigate the PAD of the >40 keV electrons as the low‐flux situation may lead to large uncertainties in computing the anisotropy factor that is defined asA = F⊥/F∥ − 1 for F⊥ > F∥, and A = −F∥/F⊥ + 1 for F⊥ < F∥. We find that, among the 150 events, 46 events have isotropic distribution (|A| ≤ 0.5); 60 events have perpendicular distribution (A > 0.5), and 44 events have field‐aligned distribution inside the FPR (A < −0.5). The perpendicular distribution appears mainly inside the growing FPR, where the flow velocity is increasing and the local flux tube is compressed. The field‐aligned distribution occurs mainly inside the decaying FPR, where the flow velocity is decreasing and the local flux tube is expanding. Inside the steady FPR, we observed primarily the isotropic distribution of suprathermal electrons. This statistical result confirms the previous case study and gives an overview of the PAD of suprathermal electrons behind DFs.

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Flux transport, dipolarization, and current sheet evolution during a double-onset substorm

Cited by 37 publications

References 66 publications

Kinetic ballooning/interchange instability in a bent plasma sheet

Kinetic ballooning/interchange instability in a bent plasma sheet

Electron‐Driven Dissipation in a Tailward Flow Burst

Pitch angle distribution of suprathermal electrons behind dipolarization fronts: A statistical overview

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