A statistical analysis of the low-energy geosynchronous plasma environment—I. Electrons

Garrett, Henry; Schwank, D. C.; Deforest, S. E.

doi:10.1016/0032-0633(81)90001-5

Cited by 36 publications

(9 citation statements)

References 14 publications

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“…of each component are listed in Table 2. Note that the four components have clear physical implication: the coldest component with < 10 eV temperature is likely of an ionospheric origin; the ∼100 eV and ∼4 keV components are typical of the "cold" and "warm" populations of ambient plasma sheet electrons [e.g., Garrett et al, 1981], the latter being the dominant population of our observation region in terms of density, and presumably constituting the main spectrum of the diffuse auroral precipitations. The hottest component (∼13 keV) represents the high-energy electron population related to the substorm injection.…”

Section: Figurementioning

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: Figurementioning

confidence: 99%

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

et al. 2010

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“…The energy spectrum of the precipitating electrons is derived from the electron flux measured by the TED and MEPED pointed toward the zenith every 2 s. The double Maxwellian distribution function is applied for the spectrum, which can be used to represent the electron flux in the magnetosphere (Garrett et al, 1981). We also examined a kappa distribution for the energy spectrum and confirmed that the results obtained with it were not so much different from the double Maxwellian distribution.…”

Section: Estimate Of Cna Using Precipitating Electron Fluxmentioning

confidence: 61%

Comparison between CNA and energetic electron precipitation: simultaneous observation by Poker Flat Imaging Riometer and NOAA satellite

et al. 2005

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Abstract. The cosmic noise absorption (CNA) is compared with the precipitating electron flux for 19 events observed in the morning sector, using the high-resolution data obtained during the conjugate observations with the imaging riometer at Poker Flat Research Range (PFRR; 65.11 • N, 147.42 • W), Alaska, and the low-altitude satellite, NOAA 12. We estimate the CNA, using the precipitating electron flux measured by NOAA 12, based on a theoretical model assuming an isotropic pitch angle distribution, and quantitatively compare them with the observed CNA. Focusing on the eight events with a range of variation larger than 0.4 dB, three events show high correlation between the observed and estimated CNA (correlation coefficient (r 0 )>0.7) and five events show low correlation (r 0 <0.5). The estimated CNA is often smaller than the observed CNA (72% of all data for 19 events), which appears to be the main reason for the low-correlation events. We examine the assumption of isotropic pitch angle distribution by using the trapped electron flux measured at 80 • zenith angle. It is shown that the CNA estimated from the trapped electron flux, assuming an isotropic pitch angle distribution, is highly correlated with the observed CNA and is often overestimated (87% of all data). The underestimate (overestimate) of CNA derived from the precipitating (trapped) electron flux can be interpreted in terms of the anisotropic pitch angle distribution similar to the loss cone distribution. These results indicate that the CNA observed with the riometer may be quantitatively explained with a model based on energetic electron precipitation, provided that the pitch angle distribution and the loss cone angle of the electrons are taken into account.

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“…As most of the observations are concentrated on the geosynchronous orbit (L=6.6), radiation belt (L=3-4), and plasma sheet (L=13), and can not cover the whole energy spectrum and disturbance levels, we have to assume a kappa distribution [10], and build an energy distribution function by fitting the observation data [11][12][13][14]. Then through linear interpolation, the initial flux is specified at all positions and disturbance levels.…”

Section: The Modelmentioning

confidence: 99%

Energetic electron flux distribution model in the inner and middle magnetosphere

Feng

2011

Sci. China Technol. Sci.

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Based on the magnetospheric kinetic theory, a model is developed to specify the flux of energetic electrons in the inner and middle magnetosphere. Under the assumption of adiabatic motion and isotropic particle distribution maintained by pitch-angle scattering, the model calculates the electron flux by following bounce-averaged electric field, gradient, and curvature drift in the time dependent electric and magnetic field, meanwhile it counts the electron loss caused by pitch angle scattering. Using the model, the electron flux distribution during a magnetic storm was calculated and compared with the observation data from the geosynchronous orbit. It is shown that the model can successfully reproduce most of the major electron flux enhancements observed at the geosynchronous orbit and generally tracks the satellite data well. The rms errors of the modeled logarithm of flux are between 0.5-1.0. magnetosphere, energetic electron, electron flux distribution Citation:Li L, Feng Y Y. Energetic electron flux distribution model in the inner and middle magnetosphere.

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A statistical analysis of the low-energy geosynchronous plasma environment—I. Electrons

Cited by 36 publications

References 14 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

Comparison between CNA and energetic electron precipitation: simultaneous observation by Poker Flat Imaging Riometer and NOAA satellite

Energetic electron flux distribution model in the inner and middle magnetosphere

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