THEMIS observation of multiple dipolarization fronts and associated wave characteristics in the near‐Earth magnetotail

Zhou, Meng; Ashour‐Abdalla, M.; Deng, Xiaohua; Schriver, D.; El‐Alaoui, M.; Pang, Y.

doi:10.1029/2009gl040663

Cited by 189 publications

(280 citation statements)

References 35 publications

(31 reference statements)

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“…2. It is seen from the figure that the B Z pulses have the typical characteristics of DFs, such as the rapid increase of the B Z component preceded by the negative B Z variation, the decrease in density behind the front, and the decrease in plasma pressure, while magnetic pressure increases across the front (e.g., Shiokawa et al, 2005;Zhou et al, 2009;Runov et al, 2009). Grigorenko et al (2018) studied the magnetic gradients observed by closely located C3 and C4 in the vicinity of the strongest B Z pulse detected by C4 at ∼ 01:39:41 UT.…”

Section: Data Descriptionmentioning

confidence: 99%

“…The strong B Z pulses had characteristics typical of DFs, such as the rapid increase of the magnetic field B Z component preceded by small negative B Z variation, the decrease in density behind the front and the decrease in plasma pressure while magnetic pressure increases across the front (e.g., Shiokawa et al, 2005;Zhou et al, 2009;Runov et al, 2009) (see Fig. 2).…”

Section: Summary Of the Dipolarization Event Featuresmentioning

confidence: 99%

“…Malykhin et al: Contrasting dynamics of electrons and protons 1992; Nakamura et al, 2002;Runov et al, 2009). DFs are associated with electron and ion acceleration (e.g., Apatenkov et al, 2007;Asano et al, 2010;Zhou et al, 2010;Fu et al, 2011;Birn et al, 2011;Grigorenko et al, 2017) as well as with various wave activities, e.g., whistler emissions, lower hybrid and electron cyclotron waves (e.g., Le Contel et al, 2009;Zhou et al, 2009;Deng et al, 2010;Khotyaintsev et al, 2011;Hwang et al, 2011;Vilberg et al, 2014;Grigorenko et al, 2016). BBFs with embedded DFs transport energy and mass from a remote tail source to the near-Earth plasma sheet (PS), where the high-speed flows are slowed down and diverted (e.g., Sergeev et al, 2009;Ge et al, 2011 and references therein).…”

Section: Introductionmentioning

confidence: 99%

“…The last may lead to additional energization and/or particles scattering and losses via processes of wave-particle interactions (e.g., Le Contel et al, 2009;Zhou et al, 2009;Deng et al, 2010;Khotyaintsev et al, 2011;Panov et al, 2013;Fu et al, 2014;Vilberg et al, 2014;Zhang and Angelopoulos, 2014;Grigorenko et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

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Contrasting dynamics of electrons and protons in the near-Earth plasma sheet during dipolarization

et al. 2018

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Abstract. The fortunate location of Cluster and the THEMIS P3 probe in the near-Earth plasma sheet (PS) (at X ∼ −7-−9 R E ) allowed for the multipoint analysis of properties and spectra of electron and proton injections. The injections were observed during dipolarization and substorm current wedge formation associated with braking of multiple bursty bulk flows (BBFs). In the course of dipolarization, a gradual growth of the B Z magnetic field lasted ∼ 13 min and it was comprised of several B Z pulses or dipolarization fronts (DFs) with duration ≤ 1 min. Multipoint observations have shown that the beginning of the increase in suprathermal (> 50 keV) electron fluxes -the injection boundary -was observed in the PS simultaneously with the dipolarization onset and it propagated dawnward along with the onset-related DF. The subsequent dynamics of the energetic electron flux was similar to the dynamics of the magnetic field during the dipolarization. Namely, a gradual linear growth of the electron flux occurred simultaneously with the gradual growth of the B Z field, and it was comprised of multiple short (∼ few minutes) electron injections associated with the B Z pulses. This behavior can be explained by the combined action of local betatron acceleration at the B Z pulses and subsequent gradient drifts of electrons in the flux pile up region through the numerous braking and diverting DFs. The nonadiabatic features occasionally observed in the electron spectra during the injections can be due to the electron interactions with high-frequency electromagnetic or electrostatic fluctuations transiently observed in the course of dipolarization.On the contrary, proton injections were detected only in the vicinity of the strongest B Z pulses. The front thickness of these pulses was less than a gyroradius of thermal protons that ensured the nonadiabatic acceleration of protons. Indeed, during the injections in the energy spectra of protons the pronounced bulge was clearly observed in a finite energy range ∼ 70-90 keV. This feature can be explained by the nonadiabatic resonant acceleration of protons by the bursts of the dawn-dusk electric field associated with the B Z pulses.

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Section: Data Descriptionmentioning

confidence: 99%

Section: Summary Of the Dipolarization Event Featuresmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Contrasting dynamics of electrons and protons in the near-Earth plasma sheet during dipolarization

et al. 2018

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“…DFs are identified by a sharp increase of B z GSM and are associated with electron and ion acceleration [Asano et al, 2010;Zhou et al, 2010;Fu et al, 2011] as well as various wave activities, e.g., electron holes, whistler, lower hybrid, and electron cyclotron waves [Le Contel et al, 2009;Sergeev et al, 2009;Zhou et al, 2009;Deng et al, 2010;Khotyaintsev et al, 2011;Hwang et al, 2011].…”

Section: Introductionmentioning

confidence: 99%

Whistler mode waves at magnetotail dipolarization fronts

et al. 2014

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We report the statistics of whistler mode waves observed in relation to dipolarization fronts (DFs) in Earth's magnetotail using data from the four Cluster spacecraft spanning a period of 9 years, 2001-2009. We show that whistler mode waves are common in a vicinity of DFs: between 30 and 60% of all DFs are associated with whistlers. Whistlers are about 7 times more likely to be observed near a DF than at any random location in the magnetotail. Therefore, whistlers are a characteristic signature of DFs. We find that whistlers are most often detected in the flux pileup region (FPR) following the DF, close to the center of the current sheet (B x ∼ 0) and in association with anisotropic electron distributions (T ⟂ > T ∥ ). This suggests that we typically observe emissions in the source region where they are generated by the anisotropic electrons produced by the betatron process inside the FPR.

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Rapid loss of the plasma sheet energetic electrons associated with the growth of whistler mode waves inside the bursty bulk flows

Cao

et al. 2013

JGR Space Physics

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[1] During the interval~07:45:36-07:54:24 UT on 24 August 2005, Cluster satellites (C1 and C3) observed an obvious loss of energetic electrons (~3.2-95 keV) associated with the growth of whistler mode waves inside some bursty bulk flows (BBFs) in the midtail plasma sheet (X GSM~À 17.25 R E ). However, the fluxes of the higher-energy electrons (≥128 keV) and energetic ions (10-160 keV) were relatively stable in the BBF-impacted regions. The energy-dependent electron loss inside the BBFs is mainly due to the energy-selective pitch angle scatterings by whistler mode waves within the time scales from several seconds to several minutes, and the electron scatterings in different pitch angle distributions are different in the wave growth regions. The plasma sheet energetic electrons have mainly a quasi-perpendicular pitch angle distribution (30°<α<150°) during the expansion-to-recovery development of a substorm (AE index decreases from 1677 nT to 1271 nT), and their loss can occur at almost all pitch angles in the wave growth regions inside the BBFs. Unlike the energetic electrons, the low-energy electrons (~0.073-2.1 keV) have initially a field-aligned pitch angle distribution (0°≤α ≤30°and 150°≤α ≤180°) in the absence of whistler mode waves, and their loss in field-aligned directions is accompanied by their increase in quasi-perpendicular directions in the wave growth regions, but the loss of the low-energy electrons inside the BBFs is not obvious in the presence of their large background fluxes. These observations indicate that the resonant electrons in an anisotropic pitch angle distribution mainly undergo the rapid pitch angle scattering loss during the wave-particle resonances.

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THEMIS observation of multiple dipolarization fronts and associated wave characteristics in the near‐Earth magnetotail

Cited by 189 publications

References 35 publications

Contrasting dynamics of electrons and protons in the near-Earth plasma sheet during dipolarization

Contrasting dynamics of electrons and protons in the near-Earth plasma sheet during dipolarization

Whistler mode waves at magnetotail dipolarization fronts

Rapid loss of the plasma sheet energetic electrons associated with the growth of whistler mode waves inside the bursty bulk flows

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