Energy spectra measured during a relativistic electron precipitation event on 2 February 1969

Larsen, T. R.; Thomas, G.R.

doi:10.1016/0021-9169(74)90199-8

Cited by 24 publications

(8 citation statements)

References 12 publications

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“…The relativistic electron flux (Table 4) Alaskan fluxes was usually 1 to 2 orders of magnitude greater than that observed for the Norwegian fluxes. These features may be related to temporal differences between the measurements at the two sites, but they are also consistent with earlier balloon and riometer findings [e.g., Bailey and Pomerantz, 1965;Hartz and Brice, 1967;Bailey, 1968;Rosenberg et al, 1972;Thorne, 1974;Larsen and Thomas, 1974] which have implied that REP distributions soften toward the poleward side of the auroral zone.…”

Section: Mae IIsupporting

confidence: 89%

Nighttime auroral energy deposition in the middle atmosphere

et al. 1984

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here are mainly relativistic electrons and bremsstrahlung X rays. Each of these sources is found to dominate ionization in a separate altitude region, with the electrons usually controlling ionization in the upper heights above 55-60 km and the X rays below to about 40 km, where cosmic rays take over. The relativistic electron ionizing radiation source has not usually been considered in modeling studies for the ion chemistry of the lower mesosphere (55-70 km), yet this radiation is capable of increasing ion concentration and electrical conductivity in excess of a factor of 10. Moreover, the persistence of relativistic electrons as an important source in all events studied here strongly suggests that this deficiency be corrected.

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Section: Mae IIsupporting

confidence: 89%

Nighttime auroral energy deposition in the middle atmosphere

et al. 1984

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“…They found an exponential energy distribution of precipitating electrons with e-folding energy between 100 and 150 keV. Parks et al (1979) later reported efolding energies as high as 200 keV, but other authors used the term ''REP'' to describe precipitation with e-folding energies of only $50 keV (Larsen and Thomas, 1976). A review of early balloon observations is given in Parks et al (1993); most of the early balloon observations focused on precipitation of p200 keV electrons and are thus not discussed in detail here.…”

Section: Historical Overviewmentioning

confidence: 97%

Review of radiation belt relativistic electron losses

Millan

Thorne

2007

Journal of Atmospheric and Solar-Terrestrial Physics

469

454

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“…On the dayside the precipitation bursts often seem to involve higher energies--hundreds of kilovolts compared with tens of kilovolts near midnight. One prominent form of high-enegy dayside precipitation has been called "relativistic electron precipitation" events (REPs) [Rosenberg et al, 1971;Larsen and Thomas, 1974;Thorne and Larsen, 1976] because they are dominated by electrons of several hundred keV. (It should be kept in mind that an REP event is not necessarily dominated by truly relativistic electrons of energies 500 keV or greater.)…”

Section: Auroral Structurementioning

confidence: 99%

Pitch angle diffusion in morningside aurorae: 1. The role of the loss cone in the formation of impulsive bursts of precipitation

Davidson¹

1986

J. Geophys. Res.

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Pitch angle diffusion of energetic electrons is important in morningside diffuse aurorae, equatorward of the auroral oval, where the plasma is shielded from the influence of large‐scale electric fields. Morningside aurorae exhibit complex spatial and temporal structure. The temporal structure is addressed in a treatment which includes the principal elements of the feedback between pitch angle diffusion and VLF wave growth. A time‐dependent bounce‐averaged pitch angle diffusion equation is derived for the electron flux in and near the loss cone. The diffusion equation includes backscatter from the atmosphere. The atmospheric backscatter is represented by an empirical model in which the pitch angle distribution in the loss cone is approximated by a Taylor series in the sine of the pitch angle. The backscatter model is adjusted to match detailed computations performed with a Fokker‐Planck code for the scattering and slowing of energetic electrons in the atmosphere. Solutions of the pitch angle diffusion equation—both steady state and time‐dependent—are used to compute anisotropies and estimate growth rates of VLF whistler mode waves. The electrons' anisotropy is most sensitive to the diffusion rate near the transition from weak to strong diffusion, where the anisotropy may become so low that VLF wave growth is halted. The principal effect of loss cone filling during an episode of strong diffusion is a sharp increase in the minimum resonant energy for wave growth and a rapid decrease of the growth rate. The characteristic time scales for wave growth and quenching due to changes in the anisotropy are of the order of 0.1–1 s and 2–10 s, respectively. The interaction of growth and decay of waves leads to precipitation bursts on a time scale of 1–50 s. The theory explains many observations of impulsive electron precipitation throughout the outer trapping regions at energies above 20–25 keV. Whether the theory can explain auroral precipitation pulsations at energies below 25 keV without invoking other wave modes remains unresolved.

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Energy spectra measured during a relativistic electron precipitation event on 2 February 1969

Cited by 24 publications

References 12 publications

Nighttime auroral energy deposition in the middle atmosphere

Nighttime auroral energy deposition in the middle atmosphere

Review of radiation belt relativistic electron losses

Pitch angle diffusion in morningside aurorae: 1. The role of the loss cone in the formation of impulsive bursts of precipitation

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