Dipolarization fronts and associated auroral activities: 1. Conjugate observations and perspectives from global MHD simulations

Ge, Yasong; Zhou, X.‐Z.; Liang, J.; Raeder, J.; Gilson, M. L.; Donovan, E.; Angelopoulos, V.

doi:10.1029/2012ja017676

Cited by 28 publications

(49 citation statements)

References 47 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…DFs are associated with plasma flows, especially earthward-moving flows (Schmid et al, 2011;Ge et al, 2012). We select all the ion velocities between t DF and t DF + 5 min for each DF event from C1 and present the ion velocity distributions of all the events in Fig.…”

Section: Statistical Resultsmentioning

confidence: 99%

“…DFs can locally accelerate ions and electrons (Zhou et al, 2010;Fu et al, 2011). Wave-particle interactions, instabilities, and increased energy of plasma particles could occur during a DF (Hwang et al, 2014;Wang et al, 2016;Grigorenko et al, 2017). DFs are found to have a close relation with fast flows in the plasma sheet and substorms (Nakamura et al, 2002;Takada et al, 2006;Volwerk et al, 2008; .…”

Section: Introductionmentioning

confidence: 99%

“…DFs play a significant role in the magnetospheric dynamics (Zhou et al, 2010;Fu et al, 2011Fu et al, , 2012cFu et al, , 2014Ge et al, 2012;Hwang et al, 2014;Wang et al, 2016). The energetic ion anisotropies in the near-Earth plasma sheet show no strong correlation with Auroral Electrojet (AE) index, indicating that its acceleration sources are localized (Luo et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

“…et Ge et al, 2012). The typical length scales of fast flows are 2-3 R E in the dawn-dusk direction and 1.5-2 R E in the north-south direction (Nakamura et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

“…Dipolarization fronts (DFs) in the magnetotail plasma sheet have been widely studied in the last decade (Ge et al, 2008(Ge et al, , 2012Volwerk et al, 2008;Schmid et al, 2011Schmid et al, , 2015Schmid et al, , 2016Runov et al, 2011;Fu et al, 2012aFu et al, , 2013Liu et al, 2013a, b;Lu et al, 2013;Huang et al, 2015;Pritchett et al, 2014;Wang et al, 2016). DFs are regarded as tangential discontinuities (Schmid et al, 2011;Fu et al, 2012a, b) usually separating the ambient dense plasma from the low-density plasma in the fast flow .…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Occurrence rate of dipolarization fronts in the plasma sheet: Cluster observations

et al. 2017

View full text Add to dashboard Cite

Abstract. We investigate the occurrence rate of dipolarization fronts (DFs) in the plasma sheet by taking full advantage of all four Cluster satellites (C1-4) from years 2001 to 2009. In total, we select 466 joint-observation DF events, in which 318, 282, 254, and 236 DFs are observed by C1, C2, C3, and C4, respectively. Our findings are as follows: (1) the maximum occurrence rate is ∼ 15.3 events per day at X ∼ 15 R E in the XY plane, and the average occurrence rate is ∼ 5.4 events per day over the whole observation period; (2) the occurrence rate on the dusk side of the plasma sheet is larger and decreases with increasing B XY /B Lobe ; (3) the occurrence rate within |Y | < 6 R E increases gradually from X ≈ −19 to −15 R E and then decreases from X ≈ −15 to −10 R E ; (4) the occurrence rate when AE > 200 nT is much larger than that when AE < 200 nT, indicating that DFs preferentially occur during high geomagnetic activity. The magnetic pileup and earthward and duskward ion flows could contribute to the increases in the occurrence rate from X ≈ −19 to −15 R E . We suggest that both geomagnetic activity and multiple DFs contribute to the high occurrence rate of the DFs. In addition, the finite length of the DF in the dawn-dusk direction can affect the chance that a satellite observes the DF.

show abstract

Section: Statistical Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…et Ge et al, 2012). The typical length scales of fast flows are 2-3 R E in the dawn-dusk direction and 1.5-2 R E in the north-south direction (Nakamura et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Occurrence rate of dipolarization fronts in the plasma sheet: Cluster observations

et al. 2017

View full text Add to dashboard Cite

show abstract

A tailward moving current sheet normal magnetic field front followed by an earthward moving dipolarization front

et al. 2014

View full text Add to dashboard Cite

A case study is presented using measurements from the Cluster spacecraft and ground‐based magnetometers that show a substorm onset propagating from the inner to outer plasma sheet. On 3 October 2005, Cluster, traversing an ion‐scale current sheet at the near‐Earth plasma sheet, detected a sudden enhancement of Bz, which was immediately followed by a series of flux rope structures. Both the local Bz enhancement and flux ropes propagated tailward. Approximately 5 min later, another Bz enhancement, followed by a large density decrease, was observed to rapidly propagate earthward. Between the two Bz enhancements, a significant removal of magnetic flux occurred, possibly resulting from the tailward moving Bz enhancement and flux ropes. In our scenario, this flux removal caused the magnetotail to be globally stretched so that the thinnest sheet formed tailward of Cluster. The thinned current sheet facilitated magnetic reconnection that quickly evolved from plasma sheet to lobe and generated the later earthward moving dipolarization front (DF) followed by a reduction in density and entropy. Ground magnetograms located near the meridian of Cluster's magnetic foot points show two‐step bay enhancements. The positive bay associated with the first Bz enhancement indicates that the substorm onset signatures propagated from the inner to the outer plasma sheet, consistent with the Cluster observation. The more intense bay features associated with the later DF are consistent with the earthward motion of the front. The event suggests that current disruption signatures that originated in the near‐Earth current sheet propagated tailward, triggering or facilitating midtail reconnection, thereby preconditioning the magnetosphere for a later strong substorm enhancement.

show abstract

Investigation of storm time magnetotail and ion injection using three‐dimensional global hybrid simulation

et al. 2014

View full text Add to dashboard Cite

2014), Investigation of storm time magnetotail and ion injection using three-dimensional global hybrid simulation, Abstract Dynamics of the near-Earth magnetotail associated with substorms during a period of extended southward interplanetary magnetic field is studied using a three-dimensional (3-D) global hybrid simulation model that includes both the dayside and nightside magnetosphere, for the first time, with physics from the ion kinetic to the global Alfvénic convection scales. It is found that the dayside reconnection leads to the penetration of the dawn-dusk electric field through the magnetopause and thus a thinning of the plasma sheet, followed by the magnetotail reconnection with 3-D, multiple flux ropes. Ion kinetic physics is found to play important roles in the magnetotail dynamics, which leads to the following results: (1) Hall electric fields in the thin current layer cause a systematic dawnward ion drift motion and thus a dawn-dusk asymmetry of the plasma sheet with a higher (lower) density on the dawnside (duskside). Correspondingly, more reconnection occurs on the duskside. Bidirectional fast ions are generated due to acceleration in reconnection, and more high-speed earthward flow injections are found on the duskside than the dawnside. Such finding of the dawn-dusk asymmetry is consistent with recent satellite observations. (2) The injected ions undergo the magnetic gradient and curvature drift in the dipole-like field, forming a ring current. (3) Ion particle distributions reveal multiple populations/beams at various distances in the tail. (4) Dipolarization of the tail magnetic field takes place due to the pileup of the injected magnetic fluxes and thermal pressure of injected ions, where the fast earthward flow is stopped. Oscillation of the dipolarization front is developed at the fast-flow braking, predominantly on the dawnside. (5) Kinetic compressional wave turbulence is present around the dipolarization front. The cross-tail currents break into small-scale structures with k ⟂ i ∼ 1, where k ⟂ is the perpendicular wave number. A sharp dip of magnetic field strength is seen just in front of the sharp rise of the magnetic field at the dipolarization front, mainly on the duskside. (6) A shear flow-type instability is found on the duskside flank of the ring current plasma, whereas a kinetic ballooning instability appears on the dawnside. (7) Shear Alfvén waves and compressional waves are generated from the tail reconnection, and they evolve into kinetic Alfvén waves in the dipole-like field region. Correspondingly, multiple field-aligned current filaments are generated above the auroral ionosphere.Geomagnetic substorms are one of the most important global-scale dynamic processes in the magnetosphere. Through the substorm, solar wind energy transmitted from the dayside magnetopause can be released from the magnetotail and injected into the high-latitude ionosphere. Since storms/substorms are conducive to strong particle injections from the tail plasma sheet and variations in the electromagneti...

show abstract

Dipolarization fronts and associated auroral activities: 1. Conjugate observations and perspectives from global MHD simulations

Cited by 28 publications

References 47 publications

Occurrence rate of dipolarization fronts in the plasma sheet: Cluster observations

Occurrence rate of dipolarization fronts in the plasma sheet: Cluster observations

A tailward moving current sheet normal magnetic field front followed by an earthward moving dipolarization front

Investigation of storm time magnetotail and ion injection using three‐dimensional global hybrid simulation

Contact Info

Product

Resources

About