The transport of plasma sheet material from the distant tail to geosynchronous orbit

Borovsky, Joseph E.; Thomsen, M. F.; Elphic, R. C.; Cayton, T. E.; McComas, D. J.

doi:10.1029/97ja03144

Cited by 128 publications

(177 citation statements)

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“…However, as we have mentioned above a few complications, such as the overall lack of latitudinal coherence of the observed PsA patches, hint that the role of ULF waves in regulating the PsA structures was only partial; some other magnetospheric processes that affect the occurrence of the PsAs, particularly in the radial direction, might be at play as well. For example, the earthward flows are known as being capable of transporting plasma "bubble/blob" structures into the near-Earth CPS, which are then subject to the turbulent mixing and/or cascading to smaller spatial scales [Borovsky et al, 1998;Borovsky and Funsten, 2003;Vörös et al, 2006]. This process might structure the CPS noncoherently and in turn contribute to the irregularly spatial occurrence of the PsAs.…”

Section: Discussionmentioning

confidence: 99%

THEMIS observations of electron cyclotron harmonic emissions, ULF waves, and pulsating auroras

et al. 2010

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[1] We present multiprobe, multi-instrument observations of the electron cyclotron harmonic (ECH) emissions and ultralow-frequency (ULF) waves from Time History of Events and Macroscale Interactions during Substorms (THEMIS) and explore their potential linkage to the concurrent ground-observed pulsating auroras (PsA) on 4 January 2009. The ECH emissions were observed as discrete packets modulated by the ULF flapping motion of the neutral sheet around the probes. Combining different data sets of the ECH observations, we infer that the ECH emission intensities were strongly fluctuating and contained multi-time scale fine structures. The distribution of PsA patches featured longitudinal "wavelength" in concert with the in situ ULF wave characteristics inferred from a cross-phase analysis. The overall activeness of the PsA correlated with the in situ-measured energetic electron fluxes and ECH wave intensities. We suggest that ECH waves played the key role in the pitch angle diffusion of the plasma sheet electrons that led to the PsA, while the ULF waves structured the plasma sheet and imposed a macroscopic effect over the spatial distribution of the PsA.

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Section: Discussionmentioning

confidence: 99%

THEMIS observations of electron cyclotron harmonic emissions, ULF waves, and pulsating auroras

et al. 2010

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“…Combined with a reasonably low value of the magnetic field (B∼5-10 nT), this leads to minimum (for the entire magnetosphere) representative values of the Alfvén velocity A=B/ 4πm p n ∼10 2 km/s. It is not inconceivable that the values A∼(30-50) km/s exist (Borovsky et al, 1998). The boundary of the plasma sheet presented in Fig.…”

Section: The Resonator In the Near-earth Part Of The Plasma Sheetmentioning

confidence: 99%

<i>Letter to the Editor</i> Why do ultra-low-frequency MHD oscillations with a discrete spectrum exist in the magnetosphere?

Leonovich

Mazur

2005

Ann. Geophys.

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Abstract.A new concept of the global magnetospheric resonator is suggested for fast magnetosonic waves in which the role of the resonator is played by the near-Earth part of the plasma sheet. It is shown that the magnetosonic wave is confined in this region of the magnetosphere within its boundaries. The representative value of the resonator's eigenfrequency estimated at f ∼1 MHz is in good agreement with observational data of ultra-low-frequency MHD oscillations of the magnetosphere with a discrete spectrum (f ∼0.8, 1.3, 1.9, 2.6... MHz). The theory explains the ground-based localization of the oscillations observed in the midnight-morning sector of the high-latitude magnetosphere.

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“…It has been suggested in particular that the density of the plasma sheet having access to the inner magnetosphere through geosynchronous orbit may have an impact on the ensuing magnetospheric activity (e.g., Borovsky et al, 1998;Kozyra et al, 1998;Thomsen et al, 1998). The studies by Thomsen et al (2003) and Lavraud et al (2005) showed that the observation of cold and dense plasma at geosynchronous orbit is likely due to the inward transport of the cold, dense plasma sheet (CDPS) that is occasionally observed in the tail of the magnetosphere (c.f.…”

Section: B Lavraud Et Al: Observation Of Two Distinct Cold Dense Imentioning

confidence: 99%

Observation of two distinct cold, dense ion populations at geosynchronous orbit: local time asymmetry, solar wind dependence and origin

et al. 2006

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Abstract. We report on the observation of two distinct cold (T i <5 keV), dense (N i >2 cm −3 ) ion populations at geosynchronous orbit. A statistical study was performed on measurements from the geosynchronous Los Alamos plasma instruments, for the period 1990-2004, and complemented by corresponding large-scale plasma sheet data obtained by mapping DMSP observations in the tail. The first population, which has previously been reported in several studies, is observed in the midnight region of geosynchronous orbit. The second population, which has drawn less attention, is detected on the dawn side of geosynchronous orbit. No such cold, dense population is observed on the dusk side of geosynchronous orbit on a frequent basis. The temporal evolution of various plasma parameters as a function of local time shows that the two populations appear at geosynchronous orbit as distinct populations, since the appearance of a midnight population is not usually associated with that of a dawn population, and vice versa. The midnight ion population is typically observed after the IMF has been northward for some time and is convected inward toward geosynchronous orbit after an observed mild southward turning of the average IMF. It is interpreted that the source of the midnight population is the cold, dense plasma sheet (CDPS). The dawn-side cold and dense ion population is associated with previously strong southward IMF and consequently occurs during substantial geomagnetic activity. These events are typically observed around the end of the main phase of the corresponding Dst decrease, down to −50 nT on average. It is unlikely that this dawn population is simply the low-latitude boundary layer (LLBL) moving closer to EarthCorrespondence to: B. Lavraud (lavraud@lanl.gov) because (1) no symmetric dusk population is observed and (2) on average a small sunward flow (∼15 km/s) is observed for those events. The cold, dense population at dawn is thus observed during active times (based on D st , K p and A E indices) in comparison with the midnight case. However, since the dawn population is observed only around the end of the main D st decrease, it is concluded that this population does not typically contribute to the D st decrease during the main phase. This population may rather be transported to geosynchronous orbit by means of a compression and convection enhancement in the magnetosphere, with a preferential access from the dawn flank with no apparent counterpart at dusk. DMSP data suggest that a cold and dense plasma source is mainly present at dawn.

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The transport of plasma sheet material from the distant tail to geosynchronous orbit

Cited by 128 publications

References 135 publications

THEMIS observations of electron cyclotron harmonic emissions, ULF waves, and pulsating auroras

THEMIS observations of electron cyclotron harmonic emissions, ULF waves, and pulsating auroras

<i>Letter to the Editor</i> Why do ultra-low-frequency MHD oscillations with a discrete spectrum exist in the magnetosphere?

Observation of two distinct cold, dense ion populations at geosynchronous orbit: local time asymmetry, solar wind dependence and origin

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The transport of plasma sheet material from the distant tail to geosynchronous orbit

Cited by 128 publications

References 135 publications

THEMIS observations of electron cyclotron harmonic emissions, ULF waves, and pulsating auroras

THEMIS observations of electron cyclotron harmonic emissions, ULF waves, and pulsating auroras

&lt;i&gt;Letter to the Editor&lt;/i&gt; Why do ultra-low-frequency MHD oscillations with a discrete spectrum exist in the magnetosphere?

Observation of two distinct cold, dense ion populations at geosynchronous orbit: local time asymmetry, solar wind dependence and origin

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<i>Letter to the Editor</i> Why do ultra-low-frequency MHD oscillations with a discrete spectrum exist in the magnetosphere?