Alfvén waves and Poynting flux observed simultaneously by Polar and FAST in the plasma sheet boundary layer

Dombeck, J.; Cattell, C. A.; Wygant, J. R.; Keiling, A.; Scudder, J. D.

doi:10.1029/2005ja011269

Cited by 73 publications

(83 citation statements)

References 24 publications

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“…The importance of wave propagation to energy transport between the tail and the auroral zone has been emphasized by observations at the plasma sheet boundary layer by Polar, Cluster, and FAST (Wygant et al, , 2002Keiling et al, 2000Keiling et al, , 2001Keiling et al, , 2002Keiling et al, , 2003Keiling et al, , 2005Angelopoulos et al, 2002;Dombeck et al, 2005). These observations show that the Poynting flux carried by shear Alfvén waves can be the dominant energy flow along auroral field lines, especially during substorm times.…”

Section: Introductionmentioning

confidence: 81%

“…This code is based on a total variance diminishing (TVD) conservative scheme that has proven to have very low numerical dissipation . This code has been used to study the MHD Kelvin-Helmholtz instability in two dimensions (Frank et al, 1996;Jones et al, 1997) as well as in three dimensions (Jones et al, 1999;Ryu et al, 2000). The threedimensional code has been applied to several challenging astrophysical problems, including the Parker instability (Kim et al, 1998(Kim et al, , 2001, and supersonic MHD jets (O'Neill et al, 2005).…”

Section: Numerical Modelmentioning

confidence: 99%

“…A final mechanism that will be considered for field-aligned current generation is linear mode conversion at the plasma sheet boundary layer (e.g., Hasegawa, 1976;Goertz and Smith, 1989;Harrold et al, 1990;Wright, 1998, 2000;and Wright and Allan, 2008). If fast mode waves are produced in the plasma sheet, they will propagate nearly isotropically through the sheet, and will quickly reach the boundary layer.…”

Section: Introductionmentioning

confidence: 99%

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Propagation of Alfvén waves in the magnetotail during substorms

2009

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Abstract. Recent observations from the THEMIS mission have focused attention on the timing of events in the magnetotail during magnetospheric substorms and other periods of geomagnetic activity. Standard models of substorms have generally emphasized convective flows as the major source of energy and momentum transport; however, Alfvén wave propagation can also be an important transport mechanism. The propagation of Alfvén waves and the related field-aligned currents are studied by means of ideal MHD simulation of the tail. Perturbations of the cross-tail current can lead to the generation of such waves, and the resulting propagation both through the tail and along the plasma sheet boundary layer can lead to enhanced transport. Implications of this wave propagation on the interpretation of results from the THEMIS mission will be discussed.

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Section: Introductionmentioning

confidence: 81%

Section: Numerical Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Propagation of Alfvén waves in the magnetotail during substorms

2009

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“…Some of these Alfvén waves are mode-converted from fast mode waves which have their origin in the solar wind or at the magnetopause (Southwood, 1974;Chen and Hasegawa, 1974;Kivelson et al, 1984). As another possibility, the observed electromagnetic fluctuations are not waves, but the magnetospheric counterpart of static ionospheric currents (Gurnett et al, 1984;Dombeck et al, 2005) as studied in the auroral region. In this case, the ionospheric electric field is related to ionospheric currents through the Pedersen conductivity.…”

Section: Introductionmentioning

confidence: 99%

Multi-spacecraft observations of small-scale fluctuations in density and fields in plasmaspheric plumes

et al. 2012

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Abstract. In this event study, small-scale fluctuations in plasmaspheric plumes with time scales of ∼10 s to minutes in the spacecraft frame are examined. In one event, plasmaspheric plumes are observed by Cluster, while IMAGE measured density enhancement at a similar location. Fluctuations in density exist in plumes as detected by Cluster and are accompanied by fluctuations in magnetic fields and electric fields. Magnetic fluctuations are transverse and along the direction of the plumes. The E/B ratio is smaller than the Alfvén velocity. Another similar event is briefly presented. We then consider physical properties of the fluctuations. Alfvén mode modulated by the feedback instability is one possibility, although non-local generation is likely. It is hard to show that the fluctuations represent a fast mode. Interchange motion is possible due to the consistency between measurements and expectations. The energy source could be a pressure or density gradient in plasmaspheric plumes. When more events are accumulated so that statistical analysis becomes feasible, this type of study will be useful to understand the time evolution of plumes.

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“…This Poynting flux, mapped to the ionosphere, was sufficient to provide enough energy for auroral arcs. The conversion of a fraction of this Poynting flux to electron fluxes was observed by Dombeck et al [2005] by comparing Polar and FAST data. Furthermore, Wygant et al [2002] observed the field-aligned acceleration of electrons at Polar in the 4-6 R E altitude range.…”

Section: Introductionmentioning

confidence: 99%

Development of parallel electric fields at the plasma sheet boundary layer

Lysak

Song

2011

J. Geophys. Res.

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[1] Many measurements of auroral particles, in particular recent measurements from the FAST satellite, indicate that the auroral electron distribution is often broad in energy and field-aligned in pitch angle. Such electrons are seen in conjunction with strong kinetic Alfvén waves with small perpendicular wavelength, and so the aurora produced by these electrons has been termed the "Alfvénic aurora." The Alfvénic aurora is predominant at the polar cap boundary of the aurora as well as in the auroral arc that brightens during substorm onset. The process of forming parallel electric fields in Alfvén waves has been investigated by means of three-dimensional two-fluid simulations. Waves with small perpendicular wavelengths can be produced by phase mixing when perpendicular gradients are present in the plasma. At lower altitudes, Alfvén waves can interact with the ionospheric Alfvén resonator and phase mix to scales of a few kilometers. At higher altitudes, the electron thermal speed becomes comparable or larger than the Alfvén speed, and parallel electric fields due to the Landau resonance can develop. This has been modeled in the fluid code by an approximation to the plasma dispersion function used in kinetic theory. Phase mixing is most effective when there are strong gradients, such as at the plasma sheet boundary layer. Simulations indicate that these processes can produce parallel electric fields on scales of a few kilometers (in the cold plasma case) to a few tens of kilometers (in the warm plasma case), comparable to the scale sizes of auroral arcs.

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Alfvén waves and Poynting flux observed simultaneously by Polar and FAST in the plasma sheet boundary layer

Cited by 73 publications

References 24 publications

Propagation of Alfvén waves in the magnetotail during substorms

Propagation of Alfvén waves in the magnetotail during substorms

Multi-spacecraft observations of small-scale fluctuations in density and fields in plasmaspheric plumes

Development of parallel electric fields at the plasma sheet boundary layer

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