Causes of Particle Precipitation along Auroral Field Lines

  • L. R. Lyons
Part of the Nobel Foundation Symposia Published by Plenum book series (NOFS, volume 54)

Abstract

Quantitative theoretical results have been obtained for three basic causes of auroral particle precipitation. Pitch angle diffusion of trapped plasma sheet particles driven by resonant wave-particle interactions leads to isotropic pitch angle distributions at lower energies, with a transition to increasingly anisotropic distributions at higher energies. Diffuse auroral electron precipitation (including that associated with pulsating aurora) can be explained by such interactions. Energization of ions in the current sheet via single particle motion leads to isotropic auroral precipitation at all energies from ∿1 keV to nearly 1 MeV. Much of observed auroral ion precipitation is consistent with that expected from this current sheet energization. The electrons responsible for discrete auroral are accelerated by a field aligned potential difference V11 > 1 keV. The overall electrodynamics of this energization, and the associated currents and electric potential variations along auroral field lines an4 within the ionosphere, can be explained by single-particle motion along the field lines and current continuity in the ionosphere. The structure of the potential distribution at high-altitudes responsible for the discrete aurora has been identified but not explained.

Keywords

Anisotropy Convection Tral Geophysics Boulder 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Anderson, H. R., 1978, Birkeland currents and auroral structure, J. Geomag. Geoelec., 30: 381.CrossRefADSGoogle Scholar
  2. Ashour-Abdalla, M., and R. M. Thorne, 1977, The importance of electrostatic ion-cyclotron instability for quiet time proton auroral precipitation, Geophys. Res. Lett.4: 45.CrossRefADSGoogle Scholar
  3. Ashour-Abdalla, M., and R. M. Thorne, 1978, Toward a unified view of diffuse auroral precipitation, J. Geophys. Res.83: 4755.CrossRefADSGoogle Scholar
  4. Bahnsen, A., 1978, Recent techniques of observations and results from the magnetopause regions, J. Atm. Terr. Phys.40: 235.CrossRefADSGoogle Scholar
  5. Bernstein, W., B. Hultqvist, and H. Borg, 1974, Some implications of low altitude observations of isotropic precipitation of ring current protons beyond the plasmapause, Planet. Space Sci.22: 767.CrossRefADSGoogle Scholar
  6. Cowley, S. W. H., 1980, Plasma populations in a simple open model magnetosphere, Space Sci. Rev.26; 217.CrossRefADSGoogle Scholar
  7. Cowley, S. W. H., and D. J. Southwood, 1980, Some properties of a steady-state geomagnetic tail, Geophys. Res. Lett.7: 833.CrossRefADSGoogle Scholar
  8. DeCoster, R. J., and L. A. Frank, 1979, Observations pertaining to the dynamics of the plasma sheet, J. Geophys. Res.84: 5099.CrossRefADSGoogle Scholar
  9. Evans, D. S., 1974, Precipitating electron fluxes formed by a magnetic field aligned potential difference, J. Geophys. Res.79: 2853.CrossRefADSGoogle Scholar
  10. Evans, D. S., 1976, The acceleration of charged particles at low altitudes, in Physics of Solar Planetary Environments, ed. D. J. Williams, Amer. Geophys. Union, 730.Google Scholar
  11. Evans, D. S., N. C. Maynard, J. Troim, T. Jacobsen, and A. Egeland, 1977, Auroral vector electric field and particle comparisons, 2. Electrodynamics of an arc, J. Geophys. Res.82: 2235.CrossRefADSGoogle Scholar
  12. Frank, L. A., and D. A. Gurnett, 1971, Distributions of plasmas and electric fields over the auroral zones and polar caps, J. Geophys. Res.76: 6829.CrossRefADSGoogle Scholar
  13. Fridman, M., and J. Lemaire, 1980, Relationship between auroral electron fluxes and field-aligned electric potential difference, J. Geophys. Res.85: 664.CrossRefADSGoogle Scholar
  14. Gorney, D. J., A. Clarke, D. Croley, J. Fennell, J. Luhmann, and P. Mizera, 1981, The distribution of ion beams and conics below 8000 km, J. Geophys. Res.86: 83.CrossRefADSGoogle Scholar
  15. Gurnett, D. A., and L. A. Frank, 1973, Observed relationships between electric fields and auroral particle precipitation, J. Geophys. Res.78: 145.CrossRefADSGoogle Scholar
  16. Harel, M., R. A. Wolf, P. H. Reiff, and H. K. Hillis, 1977, Study of plasma flow near the earth’s plasmaspause, U.S. Air Force Geophysics Lab., Report AFGL-TR-77-0286.Google Scholar
  17. Harel, M., R. A. Wolf, P. H. Reiff, and R. W. Spiro, 1980, Quantitative simulation of a magnetospheric substorm, 1. Model logic and overview, submitted to J. Geophys. Res.Google Scholar
  18. Heikkila, W. J., R. J. Pellinen, C.-G. Falthammar, and L. P. Block, 1979, Potential, and inductive electric fields in the magnetosphere during auroras, Planet. Space Sci. 27: 1383.CrossRefADSGoogle Scholar
  19. Hultqvist, B., H. Borg, P. Christophersen, W. Riedler, and W. Bernstein, 1974, Energetic protons in the keV energy range and associated keV electrons observed at various local times and disturbance levels in the upper ionosphere, NOAA Technical Report ERL 305-SEL 29, U.S. Dept. of Commerce, Boulder, CO.Google Scholar
  20. Kamide, Y., and G. Rostoker, 1977, The spatial relationships of field-aligned currents and auroral electrojets to the distribution of nightside auroras, J. Geophys. Res.82: 5589.CrossRefADSGoogle Scholar
  21. Kennel, C. F., F. L. Scarf, R. W. Fredriks, J. H. McGehee and F. V. Coroniti, 1970, VLF electric field observations in the magnetosphere, J. Geophys. Res. 75: 6136.CrossRefADSGoogle Scholar
  22. Knight, L., 1973, Parallel electric fields, Planet. Space Sci.21: 741.CrossRefADSGoogle Scholar
  23. Lemaire, J., and M. Scherer, 1974, Ionosphere-plasmasheet field-aligned currents and parallel electric fields, Planet. Space Sci.22: 1485.CrossRefADSGoogle Scholar
  24. Lennartsson, W., 1980, On the consequences of the interaction between the auroral plasma and the geomagnetic field, Planet. Space Sci.28: 135.CrossRefADSGoogle Scholar
  25. Lundin, R., and I. Sandahl, 1978, Some characteristics of the parallel electric field acceleration of electrons over discrete auroral arcs as observed from two rocket flights, Symposium on European Rocket Research, Ajaccio, Corsica, 1978, ESA SP-135, 125.Google Scholar
  26. Lundblad, J. A., F. Sorass, and K. Aarsnes, 1974, Substorm morphology of <100 keV protons, Planet. Space Sci.27: 841.CrossRefADSGoogle Scholar
  27. Lyons, L. R., 1974, Electron diffusion driven by magnetospheric electrostatic waves, J. Geophys. Res.79: 575.CrossRefADSGoogle Scholar
  28. Lyons, L. R., 1980, Generation of large-scale regions of auroral currents, electric, potentials, and precipitation by the divergence of the convection electric field, J. Geophys. Res.85: 17.CrossRefADSGoogle Scholar
  29. Lyons, L. R., 1981, Discrete aurora as the direct result of an inferred, high-altitude generating potential distribution, J. Geophys. Res.86: 1.CrossRefADSGoogle Scholar
  30. Lyons, L. R., D. S. Evans, and R. Lundin, 1979, An observed relation between magnetic field aligned electric fields and downward electron energy fluxes in the vicinity of auroral forms, J. Geophys. Res.84: 457.CrossRefADSGoogle Scholar
  31. Lyons, L. R., and T. G. Speiser, 1982, Evidence for current sheet acceleration in the geomagnetic tail, J. Geophys. Res, (in press).Google Scholar
  32. Maynard, N. C., D. S. Evans, B. Maehlum, and A. Egeland, 1977, Auroral vector electric field and particle comparisons, 1. Pre-midnight convection topology, J. Geophys. Res.82: 227.Google Scholar
  33. Schield, M. A., and L. A. Frank, 1970, Electron observations between the inner edge of plasma sheet and the plasmapause, J. Geophys. Res.75: 5401.CrossRefADSGoogle Scholar
  34. Sharber, J. R., 1981, The continuous (diffuse) aurora and auroral-E ionization, Physics of Space Plasmas, ed. by T. S. Chang, B. Coppi, and J. R. Jasperse, Scientific Publishers, Cambridge, Mass., (in press).Google Scholar
  35. Speiser, T. W., 1965, Particle trajectories in model current sheets, 1, Analytical solutions, J. Geophys. Res.70: 4219.CrossRefADSGoogle Scholar
  36. Speiser, T. W., 1967, Particle trajectories in model current sheets, 2, Applications to auroras using a geomagnetic tail model, J. Geophys. Res.72: 3919.CrossRefADSGoogle Scholar
  37. Stern, D. P., 1980, Energetics of the magnetosphere, presented at 1980 AGU Fall Meeting, NASA Technical Memorandum 82039, Goddard Space Flight Center, Greenbelt, MD.Google Scholar
  38. Vasyliunas, V. M., 1968, A survey of low energy electrons in the evening sector of the magnetosphere with 0G0-1 and 0G0-3, J. Geophys. Res.73: 2839.CrossRefADSGoogle Scholar
  39. Whalen, B. A., and I. B. McDiarmid, 1973, Pitch angle diffusion of low-energy auroral electrons, J. Geophys. Res.78: 1608.CrossRefADSGoogle Scholar
  40. Williams, D. J., 1981, Energetic ion beams at the edge of the plasma sheet: ISEE 1 observations plus a simple explanatory model, J. Geophys. Res.86: 5507.CrossRefADSGoogle Scholar
  41. Young, T. S. T., J. D. Callen, and J. E. McCune, 1973, High-frequency electrostatic waves in the magnetosphere, J. Geophys. Res.78: 1082.CrossRefADSGoogle Scholar

Copyright information

© Plenum Press, New York 1983

Authors and Affiliations

  • L. R. Lyons
    • 1
  1. 1.Space Environment Laboratory/NOAABoulderUSA

Personalised recommendations