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Volume 20, issue 10
Ann. Geophys., 20, 1647–1661, 2002
https://doi.org/10.5194/angeo-20-1647-2002
© Author(s) 2002. This work is distributed under
the Creative Commons Attribution 3.0 License.
Ann. Geophys., 20, 1647–1661, 2002
https://doi.org/10.5194/angeo-20-1647-2002
© Author(s) 2002. This work is distributed under
the Creative Commons Attribution 3.0 License.

  31 Oct 2002

31 Oct 2002

Velocities of auroral coherent echoes at 12 and 144 MHz

A. V. Koustov3,1, D. W. Danskin1, M. V. Uspensky4,2, T. Ogawa3, P. Janhunen2, N. Nishitani3, S. Nozawa3, M. Lester5, and S. Milan5 A. V. Koustov et al.
  • 1Institute of Space and Atmospheric Studies, University of Saskatchewan, 116 Science Place, Saskatoon, S7N 5E2 Canada
  • 2Finnish Meteorological Institute, Vuorikatu 15A, P.O. Box 503, Helsinki FIN-00101, Finland
  • 3Solar-Terrestrial Environment Laboratory, Nagoya University, 3–13 Honohara, Toyokawa, Aichi 442, Japan
  • 4Murmansk State Technical University, Sportivnaya 13, Murmansk, 183010 Russia
  • 5Department of Physics and Astronomy, University of Leicester, Leicester, LE1 7RH UK
  • Correspondence to: A. V. Koustov
  • (koustov@dansas.usask.ca)

Abstract. Two Doppler coherent radar systems are currently working at Hankasalmi, Finland, the STARE and CUTLASS radars operating at ~144 MHz and ~12 MHz, respectively. The STARE beam 3 is nearly co-located with the CUTLASS beam 5, providing an opportunity for echo velocity comparison along the same direction but at significantly different radar frequencies. In this study we consider an event when STARE radar echoes are detected at the same ranges as CUT-LASS radar echoes. The observations are complemented by EISCAT measurements of the ionospheric electric field and electron density behaviour at one range of 900 km. Two separate situations are studied; for the first one, CUTLASS observed F-region echoes (including the range of the EIS-CAT measurements), while for the second one CUTLASS observed E-region echoes. In both cases STARE E-region measurements were available. We show that F-region CUT-LASS velocities agree well with the convection component along the CUTLASS radar beam, while STARE velocities are typically smaller by a factor of 2–3. For the second case, STARE velocities are found to be either smaller or larger than CUTLASS velocities, depending on the range. Plasma physics of E-and F-region irregularities is discussed in attempt to explain the inferred relationship between various velocities. Special attention is paid to ionospheric refraction that is important for the detection of 12-MHz echoes.

Key words. Ionosphere (ionospheric irregularities; plasma waves and instabilities; auroral ionosphere)

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