Location of Repository

Phenomena induced by powerful HF pumping towards magnetic zenith with a frequency near the F-region critical frequency and the third electron gyro harmonic frequency

By N. F. Blagoveshchenskaya, H. C. Carlson, V. A. Kornienko, T. D. Borisova, M. T. Rietveld, Tim K. Yeoman and A. Brekke

Abstract

This paper was published as Annales Geophysicae, 2009, 27 (1, Special Issue), pp. 131-145. It is also available from http://www.ann-geophys.net/27/131/2009/angeo-27-131-2009.html. Doi: 10.5194/angeo-27-131-2009Multi-instrument observational data from an experiment on 13 October 2006 at the EISCAT/HEATING facility at Tromsø, Norway are analysed. The experiment was carried out in the evening hours when the electron density in the F-region dropped, and the HF pump frequency fH was near and then above the critical frequency of the F2 layer. The distinctive feature of this experiment is that the pump frequency was just below the third electron gyro harmonic frequency, while both the HF pump beam and UHF radar beam were directed towards the magnetic zenith (MZ). The HF pump-induced phenomena were diagnosed with several instruments: the bi-static HF radio scatter on the London-Tromsø-St. Petersburg path, the CUTLASS radar in Hankasalmi (Finland), the European Incoherent Scatter (EISCAT) UHF radar at Tromsø and the Tromsø ionosonde (dynasonde). The results show thermal electron excitation of the HF-induced striations seen simultaneously from HF bi-static scatter and CUTLASS radar observations, accompanied by increases of electron temperature when the heater frequency was near and then above the critical frequency of the F2 layer by up to 0.4 MHz. An increase of the electron density up to 25% accompanied by strong HF-induced electron heating was observed, only when the heater frequency was near the critical frequency and just below the third electron gyro harmonic frequency. It is concluded that the combined effect of upper hybrid resonance and gyro resonance at the same altitude gives rise to strong electron heating, the excitation of striations, HF ray trapping and extension of HF waves to altitudes where they can excite Langmuir turbulence and fluxes of electrons accelerated to energies that produce ionization

Publisher: Copernicus Publications on behalf of the European Geosciences Union (EGU)
Year: 2009
DOI identifier: 10.5194/angeo-27-131-2009
OAI identifier: oai:lra.le.ac.uk:2381/8173
Journal:

Suggested articles

Preview

Citations

  1. (1999). A.: Aspect angle dependence of HF enhanced incoherent backscatter, doi
  2. (1989). Airglow enhancements associated with plasma cavities formed during ionospheric heating experiments, doi
  3. (1995). al.: DARN/SuperDARN: A global view of the dynamics of highlatitude convection, doi
  4. (1993). EISCAT: Early history and the first ten years of operation, doi
  5. (2006). Electron gyroharmonic effects in ionization and electron acceleration during high-frequency pumping in the ionosphere, doi
  6. (2004). et al.: Stereo CUTLASS: A new capability for the SuperDARN radars, doi
  7. (2001). First observations of HF heaterproduced airglow at the High Frequency Active Auroral Research Program facility: Thermal excitation and spatial structuring, doi
  8. (2006). Heater-induced altitude descent of the EISCAT UHF ion line enhancements: Observations and modelling, doi
  9. (1970). Heating the F Region by Deviative Absorption of Radio Waves, doi
  10. (2005). HF-induced airglow at magnetic zenith: theoretical considerations, doi
  11. (1993). High power HF modification: Geophysics, span of EM effects, and energy budget, doi
  12. (1997). Initial backscatter occurrence statistics from the CUTLASS HF radars, doi
  13. (2002). Insights from Optical emissions, into physics of high power radio wave interactions with plasmas,
  14. (2003). Introduction to ionospheric heating at Tromsø – I. Experimental overview, doi
  15. (2003). Ionospheric electron heating, aurora and striations induced by powerful HF radio waves at high latitudes: aspect angle dependence, doi
  16. (2000). Ionospheric physics, plasma physics, and chemistry, doi
  17. (1999). Large airglow enhancements produced via wave-plasma interactions in sporadic E, doi
  18. (2002). Magnetic zenith effect in ionospheric modifications, doi
  19. (2005). Magnetic-zenith effect, doi
  20. (1972). Measurements of O(1D) quenching rates in the F region, doi
  21. (2009). Nonlinear structurAnn.
  22. (1982). Observations of fluxes of suprathermal electrons accelerated by HF excited Langmuir instabilities, doi
  23. (2004). On the onset of HF-induced airglow at HAARP, doi
  24. (1976). Parametric excitation of ionospheric irregularities extended along the magnetic field line, doi
  25. (1999). Phenomena observed by HF long-distance tools in the HF modified auroral ionosphere during magnetospheric substorm, doi
  26. Probing of medium-scale traveling ionospheric disturbances using HF-induced scatter targets, doi
  27. (1999). Radar backscattering from artificial field-aligned irregularities, doi
  28. (1974). Radio frequency scattering from a heated ionospheric volume, 1, VHF/UHF fieldaligned and plasma-line backscatter measurements, doi
  29. (2006). Recognizing the blue emission in artifical aurora, doi
  30. (1998). Self-oscillations and bunching of striations in ionospheric modifications, doi
  31. (2000). Simultaneous measurements of high-frequency pump-induced airglow and ionospheric temperatures at auroral latitudes, Adv. Polar Upper Atmos. doi
  32. (2007). Spatiotemporal evolution of radio wave pump-indiced ionospheric phenomena near the fourth electron gyroharmonic, doi
  33. (1995). Stationary state of isolated striations developed during ionospheric modification, doi
  34. (2005). The electron distribution during HF pumping – a picture painted in all colours, doi
  35. (1989). The heating of the high latitude ionosphere by high power radio waves, doi
  36. (1999). The high-latitude artificial aurora doi
  37. (2008). The Tromsø Dynasonde, doi

To submit an update or takedown request for this paper, please submit an Update/Correction/Removal Request.