Cluster observations of multiple dipolarization fronts

Hwang, Kyoung‐Joo; Goldstein, M. L.; Lee, Ensang; Pickett, J. S.

doi:10.1029/2010ja015742

Cited by 81 publications

(132 citation statements)

References 55 publications

(74 reference statements)

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“…To quantify the spectra of suprathermal electrons we assume that the differential flux of electrons (J e ) can be described by a power law in energy (W ): J e ∼ W −γ (e.g., Øieroset et al, 2002;Imada et al, 2007). In this case the spectral index γ can be calculated according to Eq.…”

Section: Data Descriptionmentioning

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%

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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: Introductionmentioning

confidence: 99%

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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“…As an example, we describe the work of Hwang et al (2011a), who reported Cluster observations of multiple DFs observed on August 15, 2001. The six DFs are indicated by magenta vertical lines numbered 1-6, at the top of Fig.…”

Section: Plasma Phenomena As Measured In Three Dimensionsmentioning

confidence: 99%

“…DFs are thought to result from magnetic reconnection in which the exhaust jets and entrained magnetic fluxes from the reconnection region pile up, forming a front of increased current-sheet-normal magnetic field (Hoshino et al 2001;Hoshino 2005;Nakamura et al 2009;Sitnov et al 2009;Fu et al 2013). DFs have drawn wide attention because they significantly affect the acceleration and transport of plasmas (see e.g., Sergeev et al 2009;Zhou et al 2009;Deng et al 2010b;Ashour-Abdalla et al 2011;Fu et al 2011;Hwang et al 2011a;Birn et al 2013). DFs are also thought to play a significant role in populating the inner magnetosphere by transporting plasmas from the mid-tail (15-30 R E ) to the near-Earth (10-15 R E ) plasmasheet and, in some cases, into the inner magnetosphere (Delcourt et al 1990;Delcourt 2002;Jones et al 2006;Runov et al 2009;AshourAbdalla et al 2011).…”

Section: Plasma Phenomena As Measured In Three Dimensionsmentioning

confidence: 99%

Multipoint observations of plasma phenomena made in space by Cluster

et al. 2015

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Plasmas are ubiquitous in nature, surround our local geospace environment, and permeate the universe. Plasma phenomena in space give rise to energetic particles, the aurora, solar flares and coronal mass ejections, as well as many energetic phenomena in interstellar space. Although plasmas can be studied in laboratory settings, it is often difficult, if not impossible, to replicate the conditions (density, temperature, magnetic and electric fields, etc.) of space. Single-point space missions too numerous to list have described many properties of near-Earth and heliospheric plasmas as measured both in situ and remotely (see http://www.nasa.gov/missions/#.U1mcVmeweRY for a list of NASA-related missions). However, a full description of our plasma environment requires three-dimensional spatial measurements. Cluster is the first, and until data begin flowing from the Magnetospheric Multiscale Mission (MMS), the only mission designed to describe the three-dimensional spatial structure of plasma phenomena in geospace. In this paper, we concentrate on some of the many plasma phenomena that have been studied using data from Cluster. To date, there have been more than 2000 refereed papers published using Cluster data but in this paper we will, of necessity, refer to only a small fraction of the published work. We have focused on a few basic plasma phenomena, but, for example, have not dealt with most of the vast body of work describing dynamical phenomena in Earth's magnetosphere, including the dynamics of current sheets in Earth's magnetotail and the morphology of the dayside high latitude cusp. Several review articles and special publications are available that describe aspects of that research in detail and interested readers are referred to them (see for example, Escoubet et al.

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Cluster observations of multiple dipolarization fronts

Cited by 81 publications

References 55 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

Multipoint observations of plasma phenomena made in space by Cluster

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