Low frequency eigenmodes of thin anisotropic current sheets and Cluster observations

Zelenyǐ, L. M.; Artemyev, А. V.; Petrukovich, A. A.; Nakamura, R.; Malova, H. V.; Попов, В. В.

doi:10.5194/angeo-27-861-2009

Cited by 74 publications

(50 citation statements)

References 27 publications

(41 reference statements)

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Figure 7 shows a typical value of | B Z / X|∼0.5 nA/m 2 and B X / Z∼40 nA/m 2 and using the observed proton number density 0.4/cc, we obtain ω f or γ f to be 0.14 corresponding to a period/growth time of 34 s. This is a comparable value of the estimated flapping period before. Kink-mode oscillation was also obtained in Zelenyi et al (2009) in a several-ion scale thin current sheet, which was the case for the observed current sheet. The theoretical prediction of the phase velocity being comparable to the drift velocity, and the wavelength to be comparable to the thickness of the current sheet is fulfilled in this observation within a factor of 6.…”

Section: Discussion and Summarymentioning

confidence: 97%

“…The opposite B X variation below and above the equator suggests a sausage mode with a period of 2-3 min for this variation. Theoretical models of low-frequency kink-mode oscillation of a current sheet with finite B Z have been presented in several papers (Golovchanskaya and Maltsev, 2005;Erkaev et al, 2008;Zelenyi et al, 2009) stimulated by Cluster current sheet observations in the mid tail (e.g., Sergeev et al, 2003;Runov et al, 2005a). Compared to the previous kink mode observations by Cluster (Sergeev et al, 2003;Runov et al, 2005b;Zhang et al, 2005;Volwerk et al, 2008) in the mid-tail in a relatively thicker current sheet and during predominantly quiet intervals, the oscillation shown in this study have higher frequency, observed at a thinner current sheet but more closer to the Earth and associated with clear dipolarization and fast flows.…”

Section: Discussion and Summarymentioning

confidence: 99%

See 1 more Smart Citation

Evolution of dipolarization in the near-Earth current sheet induced by Earthward rapid flux transport

Nakamura

Retinò²,

Baumjohann³

et al. 2009

Ann. Geophys.

Self Cite

140

143

View full text Add to dashboard Cite

Abstract. We report on the evolution of dipolarization and associated disturbances of the near-Earth current sheet during a substorm on 27 October 2007, based upon Cluster multi-point, multi-scale observations of the night-side plasma sheet at X∼−10 R E . Three dipolarization events were observed accompanied by activations on ground magnetograms at 09:07, 09:14, and 09:22 UT. We found that all these events consist of two types of dipolarization signatures: (1) Earthward moving dipolarization pulse, which is accompanied by enhanced rapid Earthward flux transport and is followed by current sheet disturbances with decrease in B Z and enhanced local current density, and subsequent (2) increase in B Z toward a stable level, which is more prominent at Earthward side and evolving tailward. During the 09:07 event, when Cluster was located in a thin current sheet, the dipolarization and fast Earthward flows were also accompanied by further thinning of the current sheet down to a half-thickness of about 1000 km and oscillation in a kinklike mode with a period of ∼15 s and propagating duskward. Probable cause of this "flapping current sheet" is shown to be the Earthward high-speed flow. The oscillation ceased as the flow decreased and the field configuration became more dipolar. The later rapid flux transport events at 09:14 and 09:22 UT took place when the field configuration was initially more dipolar and were also associated with B Z disturbance and local current density enhancement, but to a lesser degree. Hence, current sheet disturbances induced by initial Correspondence to: R. Nakamura (rumi.nakamura@oeaw.ac.at) dipolarization pulses could differ, depending on the configuration of the current sheet.

show abstract

Section: Discussion and Summarymentioning

confidence: 97%

Section: Discussion and Summarymentioning

confidence: 99%

Evolution of dipolarization in the near-Earth current sheet induced by Earthward rapid flux transport

Nakamura

Retinò²,

Baumjohann³

et al. 2009

Ann. Geophys.

Self Cite

140

143

View full text Add to dashboard Cite

show abstract

“…In majority of cases current density profiles were distinctly different from the classical Harris shape (Harris, 1962) and were categorized as embedded, bifurcated, or asymmetric (Asano et al, 2005;Runov et al, 2006;Nakamura et al, 2006;Thompson et al, 2006). Another unexpected feature was abundance of strongly tilted (in the YZ GSM plane) sheets with rather variable profiles (Sergeev et al, 2004;Petrukovich et al, 2006), which most likely represent nonstationary structures (Malova et al, 2007;Petrukovich et al, 2008;Zelenyi et al, 2009;Erkaev et al, 2009) and often cannot be explained by motion of the sheet as a whole. A variety of TCS models available now is also quite wide (Kropotkin and Domrin, 1996;Schindler and Birn, 2002;Sitnov et al, 2006;Zelenyi et al, 2004;Yoon and Lui, 2004) (see Sect.…”

Section: Introductionmentioning

confidence: 99%

Thin embedded current sheets: Cluster observations of ion kinetic structure and analytical models

et al. 2009

Self Cite

View full text Add to dashboard Cite

Abstract. Kinetic structure of embedded thin horizontal current sheets is investigated. Current density estimated by curlometer technique is in general agreement with a sum of electron and proton currents. Embedding of observed thin current sheets in the much wider plasma sheet is apparent in the current density profiles. Ion velocity distributions consist of two parts: the cold non-drifting core likely belongs to the plasma sheet background, while the hotter asymmetric "wings" carry the main portion of the current. Oxygen ions (if present) and higher-energy tails of distribution function can contribute up to 30% of the total current. We compared current density profiles across sheets with three typical current sheet models. Models which allow embedding, describe observed structures equally well at the level of experimental accuracy.

show abstract

“…Flapping, how it is recognised now, is one of the most widespread types of CS activity (e.g. Zhang et al, 2002;Sergeev et al, 2004). However, other manifestations of CS dynamics (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…Sergeev et al, 1998;Runov et al, 2012), investigate Hall electric field configuration in CSs (Wygant et al, 2005;Vasko et al, 2014), and test numerical models of CS instability (e.g. Karimabadi et al, 2003b;Sitnov et al, 2006;Zelenyi et al, 2009;Nakamura et al, 2009). The opportunity of four-spacecraft measurements of magnetic field provided by the Cluster mission was actively used to investigate details of the CS flapping (Runov et al, 2005a;Petrukovich et al, 2006Petrukovich et al, , 2008Rong et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Current sheet flapping in the near-Earth magnetotail: peculiarities of propagation and parallel currents

et al. 2016

View full text Add to dashboard Cite

Abstract. We consider series of tilted current sheet crossings, corresponding to flapping waves in the near-Earth magnetotail. We analyse Cluster observations from 2005 to 2009, when spacecraft visited the magnetotail neutral plane near X ∈ [−17, −8], Y ∈ [−16, −2] R E (in the GSM system). Large separation of spacecraft allows us to estimate both local and global properties of flapping current sheets. We find significant variation in flapping wave direction of propagation between the middle tail and flanks. Th series of tilted current sheets represent the system of periodic, almost parallel currents with typical thickness of current filaments about L = 0.4 R E . The earthward gradients of B z magnetic field are reduced within this current system in comparison with the gradients in the quiet near-Earth magnetotail. The wavelength (i.e. a distance between two crossings of current sheets with the same orientations) of the flapping waves is larger than 2π L for most of observations. The velocity of flapping wave propagation is about ion bulk velocity and is significantly lower than the velocity of ion drift relative to electrons. We discuss possible drivers of flapping and estimate the amplitude of the total parallel current generated by flapping waves.

show abstract

Low frequency eigenmodes of thin anisotropic current sheets and Cluster observations

Cited by 74 publications

References 27 publications

Evolution of dipolarization in the near-Earth current sheet induced by Earthward rapid flux transport

Evolution of dipolarization in the near-Earth current sheet induced by Earthward rapid flux transport

Thin embedded current sheets: Cluster observations of ion kinetic structure and analytical models

Current sheet flapping in the near-Earth magnetotail: peculiarities of propagation and parallel currents

Contact Info

Product

Resources

About