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Velocity of E region SuperDARN echoes and ExB plasma drift
  • Alexandre Koustov,
  • Michael Luciuk,
  • Rob Gillies
Alexandre Koustov
University of Saskatchewan

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Michael Luciuk
University of Saskatchewan
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Rob Gillies
University of Calgary
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Rankin Inlet (RKN) SuperDARN radar observations simultaneously with the Resolute Bay Incoherent scatter radar in nearly coinciding beams are considered to investigate the relationship between the velocity of HF echoes and ExB plasma drift component along the RKN beam. We focus on a case of observations roughly along the flow direction on 6 March 2016. We show that, depending on HF operating frequency, the RKN radar detects either E or F region echoes. For the E region echoes and fast flows of 700-1000 m/s, HF velocities are of two types: very slow with speeds below 100 m/s and fast with speeds up to 400 m/s. Velocities of slow echoes can be of opposite polarity at 10 and 12 MHz and not coincide with the ExB drift polarity. Velocities of fast echoes are somewhat larger at 12 MHz as compared to 10 MHz and both are less than the expected ion-acoustic speed of plasma at typical electrojet heights. No strong range (presumably, aspect angle) attenuation effect is noticed in the range profiles of such echoes. We relate the first type of echoes to the neutral wind turbulence while the second type – to the Farley-Buneman (FB) plasma instability processes. Periods have been noticed when E region echoes had speeds of ~ 200 m/s which is well below the ion-acoustic speed and ExB drift component. We hypothesize that these echoes are owing to FB irregularities generated at low electrojet heights. The observations show existence of extended periods when the RKN radar detects F region echoes at 10 MHz and E region echoes at 12 MHz at the same ranges implying that the “transition region/ranges” for E and F region detection is very sensitive to the observational conditions.