Abstract
Analysis of the plasma wave observation data provided by the plasma waves and sounder experiment (PWS) on board the Akebono satellite frequently reveals the presence of electrostatic electron cyclotron harmonic (ESCH) waves in the low-latitude region (MLAT < 45°) of the plasmasphere within an altitude range from about 3000 km to the apogee of the satellite (initial apogee was 10,500 km). Even at moderate or low geomagnetic activity, intense ESCH waves often appear near the equatorial region of the plasmasphere above the upper hybrid resonance (UHR) frequency at the lowest harmonic number branch of the fQn ESCH waves. We identified these plasma waves as the equatorial plasmasphere fQn waves (EP-fQn). The spectra of the EP-fQn waves are characterized by a narrow band structure and by a strong nature, with a wave intensity that ranges from 3.46 × 10-8 to 3.31 × 10-4 V/m. The maximum intensity is nearly coincident with the upper limit of the PWS receiver in the low-gain mode. Statistical analysis results reveal that the EP-fQn waves are observable in all the local time sectors; however, the occurrence probability shows a clear enhancement in the early morning sector of 01–03 MLT in the plasmasphere. The EP-fQn wave activities are suppressed within a period of strong magnetic disturbances as well as solar minimum phase. The linear dispersion relation analysis using a two-component plasma model reveals that supra-thermal plasma with the energy of about 750 eV and with a large temperature anisotropy (A = T-perp/T-parallel–1 > 40) must be present in order to realize an appearance of a positive growth rate at the observed frequency and propagation angle of the ESCH waves. Since the hot plasma with such a high anisotropy has not been detected, the validity of the present two-component plasma model remains an open question. The occurrence feature of the ESCH waves showed that there is a constant activation or a constant flow-in of free energy to generate the strong plasma instability of ESCH waves near the post-midnight sector of the plasmasphere. The existence of ESCH waves revealed that the nature of the plasmaspheric plasma is more turbulent and active than has been believed.
Article PDF
Similar content being viewed by others
References
Abe, T., K. Oyama, H. Amemiya, S. Watanabe, T. Okuzawa, and K. Schlegel, Measurements of temperature and velocity distribution of thermal electrons by the Akebono (EXOS-D) satellite—Experimental setup and preliminary results-, J. Geomag. Geoelectr., 42, 537–554, 1990.
Anderson, R. A. and K. Maeda, VLF emissions associated with enhanced magnetospheric electrons, J. Geophys. Res., 82, 135–146, 1977.
Ashour-Abdalla, M. and C. F. Kennel, Nonconvective and convective electron cyclotron harmonic instabilities, J. Geophys. Res., 83, 1531–1543, 1978.
Bernstein, I. B., Waves in a plasma in a magnetic field, Phys. Rev., 109, 10–21, 1958.
Birmingham, T. J., J. K. Alexander, M. D. Desch, R. F. Hubbard, and B. M. Pedersen, Observations of electron gyroharmonic waves and the structure of the Io torus, J. Geophys. Res., 86, 8497–8507, 1981.
Burke, W. J., A. G. Rubin, D. A. Hardy, and E. G. Holeman, Banded electron structures in the plasmasphere, J. Geophys. Res., 100, 7759–7769, 1995.
Christiansen, P., P. Gough, G. Martelli, J.-J. Bloch, N. Cornilleau, J. Etch-eto, R. Gendrin, D. Jones, C. Beghin, and P. Dercreau, Geos I: Identification of natural magnetospheric emissions, Nature, 272, 682–686, 1978.
Crawford, F. W., A review of cyclotron phenomena in plasma, Nucl. Fusion, 5, 73, 1965.
Curtis, S. A. and C. S. Wu, Electrostatic and electromagnetic gyrohar-monic emissions due to energetic electrons in magnetospheric plasmas, J. Geophys. Res., 84, 2057–2075, 1979.
Daglis, I. A., R. M. Thorne, W. Baumjohann, and S. Orsini, The terrestrial ring current: Origin, formation, and decay, Rev. Geophys., 37, 407–438, 1999.
Fredricks, R. W., Plasma instability at (n + 1/2) f c and its relationship to some satellite observations, J. Geophys. Res., 76, 5344–5348, 1971.
Fredricks, R. W. and F. L. Scarf, Recent studies of magnetospheric electric field emissions above the electron gyrofrequency, J. Geophys. Res., 78, 310–314, 1973.
Fukunishi, H., R. Fujii, S. Kokubun, K. Hayashi, T. Tohyama, Y. Tone-gawa, S. Okano, M. Sugiura, K. Yumoto, I. Aoyama, T. Saito, T. Iijima, A. Nishida, and M. Natori, Magnetic field observations on the Akebono (EXOS-D) satellite, J. Geomag. Geoelectr., 42, 385–409, 1990.
Harris, E. G., Unstable plasma oscillations in a magnetic field, Phys. Rev. Lett., 2, 34–36, 1959.
Horne, R. B., R. M. Thorne, N. P. Meredith, and R. R. Anderson, Diffuse auroral electron scattering by electron cyclotron harmonic and whistler mode waves during an isolated substorm, J. Geophys. Res., 108, 1290, doi:10.1029/2002JA009736, 2003.
Hubbard, R. F. and T. J. Birmingham, Electrostatic emissions between electron gyroharmonics in the outer magnetosphere, J. Geophys. Res., 83, 4837–4850, 1978.
Kennel, C. F., F. L. Scarf, R. W. Fredricks, J. H. McGehee, and F. V. Coro-niti, VLF electric field observations in the magnetosphere, J. Geophys. Res., 89, 3015–3018, 1970.
Koons, H. C., B. C. Edgar, J. F. Fennell, and D. J. Georney, Observations of electron cyclotron harmonic emissions associated with field-aligned electron beams, J. Geophys. Res., 92, 7531–7537, 1987.
Kurth, W. S., J. D. Craven, L. A. Frank, and D. A. Gurnett, Intense electrostatic waves near the upper hybrid resonance frequency, J. Geophys. Res., 84, 4145–4164, 1979.
LaBelle, J., D. R. Ruppert, and R. A. Treumann, A statistical study of banded magnetospheric emissions, J. Geophys. Res., 104, 293–303, 1999.
Lyons, L. R., Electron diffusion driven by magnetospheric electrostatic waves, J. Geophys. Res., 79, 575–580, 1974.
Matsumoto, H. and H. Usui., Intense bursts of electron cyclotron harmonic waves near the dayside magnetopause observed by GEPTAIL, Geophys. Res. Lett., 24, 49–52, 1997.
Nelms, G. L. and G. E. K. Lockwood, Early results from the topside sounder in the Alouette II satellite, Space Res., 7, 604–623, 1966.
Nishimura, Y., A. Shinbori, T. Ono, M. Iizima, A. Kumamoto, and A. Morioka, Evolution of pitch angle distributions of relativistic electrons in the radiation belt during magnetic storms, J. Geophys. Res., 2005 (submitted).
Oya, H., Sequence of diffuse plasma resonances observed on Alouette 2 ionograms, J. Geophys. Res., 75, 4279–4285, 1970.
Oya, H., Verification of theory on weak turbulence relating to the sequence of diffuse plasma resonances in space, Phys. Fluids, 14, 2487–2499, 1971.
Oya, H., Plasma flow hypothesis in the magnetosphere relating to frequency shift of electrostatic plasma waves, J. Geophys. Res., 80, 2783–2789, 1975.
Oya, H., Studies on plasma and plasma waves in the plasmasphere and auroral particle acceleration region, by PWS on board the EXOS-D (Akebono) satellite, J. Geomag. Geoelectr., 43, 369–393, 1991.
Oya, H., T. Ono, and T. Kamada, Stimulation of plasma waves in the magnetosphere using satellite JIKIKEN (EXOS-B), Part I, Observation of plasma resonances, J. Geomag. Geoelectr., 33, 3–25, 1981.
Oya, H., A. Morioka, K. Kobayashi, M. Iizima, T. Ono, H. Miyaoka, T. Okada, and T. Obara, Plasma wave observation and sounder experiments (PWS) using the Akebono (EXOS-D) satellite—instrumentation and initial results including discovery of the high altitude equatorial plasma turbulence, J. Geomag. Geoelectr., 42, 411–422, 1990.
Oya, H., M. Iizima, and A. Morioka, Plasma turbulence disc circulating the equatorial region of the plasmasphere identified by the plasma wave detector (PWS) onboard the Akebono (EXOS-D) satellite, Geophys. Res. Lett., 18, 329–332, 1991.
Paranicas, C., W. J. Hughes, H. J. Singer, and R. R. Anderson, Banded electrostatic emissions observed by the CRRES plasma wave experiment, J. Geophys. Res., 97, 13889–13898, 1992.
Roeder, J. L. and H. C. Koons, A survey of electron cyclotron waves in the magnetosphere and the diffuse auroral electron precipitation, J. Geophys. Res., 94, 2529–2541, 1989.
Roeder, J. L., V. Angelopoulos, W. Baumjohann, and R. R. Anderson, Observations of correlated broadband electrostatic noise and electron cyclotron emissions in the plasma sheet, Geophys. Res. Lett., 18, 53–56, 1991.
Rymer, A. M., A. J. Coates, K. Svenes, G. A. Abel, D. R. Linder, B. Narheim, M. Thomsen, and D. T. Young, Cassini plasma spectrometer electron spectrometer measurements during the Earth swing-by on August 18, 1999, J. Geophys. Res., 106, 30177–30198, 2001.
Shaw, R. L. and D. A. Gurnett, Electrostatic noise bands associated with the electron gyrofrequency and plasma frequency in the outer magnetosphere, J. Geophys. Res., 80, 4259–4271, 1975.
Shawhan, S. D., Magnetospheric plasma wave research 1975–1978, Reviews of Geophys. And Space Phys., 17, 705–724, 1979.
Shima, Y. and L. S. Hall, Electrostatic instabilities in a plasma with anisotropic velocity distribution, Phys. Rev., 139, A1115–A1116, 1965.
Shinbori, A., Y. Nishimura, T. Ono, M. Iizima, A. Kumamoto, and H. Oya, Electrodynamics in the duskside inner magnetosphere and plas-masphere during a super magnetic storm on March 13–15, 1989, Earth Planets Space, 57, 643–659, 2005.
Walt, M., Introduction to Geomagnetically Trapped Particle, Cambrige Unversity Press, Cambrige, 1994.
Warren, E. S. and E. L. Hagg, Observation of electrostatic resonances of the ionospheric plasma, Nature, 220, 466–468, 1968.
Young, T. S. T., J. D. Callen, and J. E. McCune, High-frequency electrostatic waves in the magnetosphere, J. Geophys. Res., 78, 1082–1099, 1973.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made.
The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder.
To view a copy of this licence, visit https://creativecommons.org/licenses/by/4.0/.
About this article
Cite this article
Shinbori, A., Ono, T., Iizima, M. et al. Electrostatic electron cyclotron harmonic waves observed by the Akebono satellite near the equatorial region of the plasmasphere. Earth Planet Sp 59, 613–629 (2007). https://doi.org/10.1186/BF03352723
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1186/BF03352723