Bistatic Auroral Radar System radar events showing a repetitive equatorward (or radarward) traveling band signature in the range‐time‐intensity plots have been analyzed. The associated pulsations have many features in common with previously reported high‐m storm time Pc 5 pulsations. The periods, azimuthal wave numbers (m), Dst dependence, and polarization ellipses are similar. One difference is also seen. The pulsation phase velocity of our events often has a significant equatorward component in the ionosphere. However, of the three cases for which the phase velocity direction in the magnetospheric equatorial plane was determined, one had phase velocities close to azimuthal at both locations, one had an azimuthal phase velocity in the magnetosphere but an equatorward component of the phase velocity in the ionosphere, and the final event had equatorward or inward components of phase velocity at both locations. These events are very similar to the equatorward traveling bands events observed by the Sweden and Britain Auroral Radar Experiment system (Tian et al., 1991; Yeoman et al., 1992) except that our m values are distinctly larger. If coupling to energetic protons is involved in exciting these pulsations, this difference implies that the energy of the protons involved decreases with increasing L of the interaction location. Finally, our data do not lend themselves to the plasmapause field line resonance interpretation of Tian et al. (1991).
We report energetic ion and electron, wave, and ambient plasma observations from two sounding rockets which were launched from Churchill, Canada, into the expansive phases of two auroral substorms and which passed through source regions of transversely accelerated ionospheric ions (TAI). The two events were observed at low altitudes (400-600 kin) and resulted in ion energization of hundreds of electron volts. In the acceleration region, the ionospheric ion velocity distribution function in the direction perpendicular to the local magnetic field (lB) displayed a distinct, non-Maxwellian, high-energy tail, suggesting ion cyclotron heating. The plasma density was lower than theoretical quiescent values, by as much as 2 decades in the stronger event. Strong thermal ion drift was observed in the perpendicular (lB) direction, but was absent in the parallel (liB) direction. Large-amplitude, low-frequency fluctuations in plasma density were present, and a number of wave modes were observed, including upper hybrid and Langmuir waves, and whistler, ion acoustic, and ion cyclotron waves. No consistent correlation existed between the energetic particle precipitation and the TAI. However, strong field-aligned electron enhancements were observed at times coincident with the TAI acceleration region. The characteristics of the TAI ion energy spectra were consistent with a simple model of ion cyclotron acceleration and energy loss due to ion-neutral collisions. These observations are discussed in terms of current theories on electrostatic ion cyclotron acceleration and lower hybrid acceleration. concluded from their S3-3 data that, at least for O + conics, a substantial fraction of the ion energy originated from transverse acceleration. Gorney et al. [1981] found that conic source regions, estimated by mapping the pitch angles of the peak measured fluxes in conics down to their magnetic mirror points, tended to be below 3000 km. These authors also found that perpendicular conics (conics with peak fluxes within a few degrees of 90 ø and also referred to as transversely accelerated 341 ions, TAI) were observed primarily in the 1500-to 2000-km altitude region.In this paper, we report particle, wave, and ambient plasma observations from two sounding rockets which passed through such conic source regions. The events were observed at low altitudes (400-600 km) and resulted in ion energization of hundreds of electron volts. EXPERIMENTSBlack Brant rockets AAF-IVB-33 and AAF-IVB-36 were launched from Churchill Research Range, Manitoba, Canada (58.74øN, 93.82øW) into the expansive phases of two auroral substorms, IVB-33 on February 5, 1976, at 0522:55 UT (2322:55 LT) to an apogee of 735 km and IVB-36 on January 26, 1981, at 0720:06 UT (0120:06 LT) to an apogee of 585 km. Both payloads were instrumented with electrostatic analyzers to measure electron and ion spectra in the 0.1-to 20-keV/q range, solid state detectors to measure energetic particles (E > 20 keV/q), low-energy ion sensors to measure ambient ion velocity distributions (0.1-5 ...
Some 7700 radio aurora spectra obtained from a six link 50‐MHz CW radar network set up on the Canadian prairies were analyzed with respect to the distributions of mean Doppler shift, spectral width and skewness. A comparison with recently published SABRE results obtained at 153 MHz (Schlegel et al., 1986) shows substantial differences in the distributions which are probably due to different experimental and geophysical conditions. Our spectra are mostly broad with mean Doppler shifts close to zero (type II spectra). The typical groupings of type I and type III spectra are clearly identified. All types appear to be in general much more symmetric than those recorded with SABRE, and the skewness is only weakly dependent on the sign of the mean Doppler shift. Its distribution peaks near zero and shows a weak positive correlation with the type II Doppler shifts while the mostly positive type I Doppler shifts are slightly negatively correlated with the skewness.
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