Location of Repository

The effects of high frequency ULF wave activity on the spectral characteristics of coherent HF radar returns: a case study

By D. M. Wright, Tim K. Yeoman and E. E. Woodfield


It is now a common practice to employ ground-based radars in an attempt to distinguish between those regions of the Earth's upper atmosphere which are magnetically conjugate to open and closed magnetic field lines. Radar returns from ionospheric irregularities inside the polar cap and cusp regions generally exhibit large spectral widths in contrast to those which exist on closed field lines at lower latitudes. It has been suggested that the so-called Spectral Width Boundary (SWB) might act as a proxy for the open-closed field line boundary (OCFLB), which would then be an invaluable tool for investigating reconnection rates in the magnetosphere. The exact cause of the increased spectral widths observed at very high latitudes is still subject to considerable debate. Several mechanisms have been proposed. This paper compares a dusk-sector interval of coherent HF radar data with measurements made by an induction coil magnetometer located at Tromsø, Norway (66° N geomagnetic). On this occasion, a number of equatorward excursions of the SWB in the radar backscatter are accompanied by increases in spectral power of ULF waves in the Pc1-2 frequency band as the SWB passes overhead. Thus, these observations support the possibility that high-frequency magnetospheric wave activity at least contribute to the observed spectral characteristics and that such wave activity might play a significant role in the nightside ionosphere

Topics: Ionosphere (auroral ionosphere), Magnetospheric physics (MHD waves and instabilities), Radio science (ionospheric physics)
Year: 2004
DOI identifier: 10.5194/angeo-22-1843-2004
OAI identifier: oai:lra.le.ac.uk:2381/714

Suggested articles



  1. (2001). A case study of HF radar spectra and 630.0 nm auroral emission in the pre midnight sector, doi
  2. (1995). DARN/SuperDARN: a global view of the dynamics of high-latitude convection, doi
  3. (1997). Ground observations and possible source regions of two types of Pc1-2 micropulsations at very high latitudes, doi
  4. (1987). HF radar observations of E region plasma irregularities produced by oblique electron streaming, doi
  5. (2002). High and variable spectral width in the pre-dawn sector: A case study involving CUTLASS, EISCAT, ESR and optical data,
  6. (2004). High resolution observations of spectral width features associated with ULF wave signatures in artificial HF radar backscatter, doi
  7. (1992). Identification of the magnetospheric cusp and cleft using Pc1-2 ULF pulsations, doi
  8. (1997). Initial backscatter occurrence statistics from the CUTLASS HF radars, doi
  9. (1991). Magnetospheric boundary dynamics: DE1 and DE2 observations near the magnetopause and cusp, doi
  10. On the factors conditioning the Doppler spectral width determined from SuperDARN HF radars, doi
  11. (1999). On the SuperDARN autocorrelation function observed in the ionospheric cusp, doi
  12. (2001). Pc1 pearls revisited: structured electromagnetic ion cyclotron waves on Polar satellite and on ground, doi
  13. (1996). Pc1 waves in the ionosphere: a statistical study, doi
  14. (1961). Pulsations of the Earth’s electromagnetic field with periods of 1 to 15 seconds and their connection with phenomena in the high atmosphere, doi
  15. (1964). The development of auroral substorm, doi
  16. The effects of high-frequency ULF wave activity on coherent HF radar returns 1849 doi
  17. (2003). The role of Pc1-2 waves in spectral broadening of SuperDARN echoes from high latitudes, doi
  18. (1990). Viking magnetic and electric field observations of Pc1 waves at high latitudes, doi

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