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20 Feb/95, 16:32 - 16:34 UT

Solar plasma speeds as measured by WIND were very constant at 400 km/s throughout the event. IMF parameters as measured by WIND indicate a positive tex2html_wrap_inline5474 and a tex2html_wrap_inline4540 change from positive to zero during the event. IMP8 recorded a sharp drop of the tex2html_wrap_inline5386 and the tex2html_wrap_inline5474 components preceding and during the event while tex2html_wrap_inline4540 remained positive and small. The tex2html_wrap_inline4548 index at the time of the event was 2.0 and falling.

The overview in Figure 5.52 indicates good scattering conditions for both radars. The Kapuskasing radar shows a region of missing backscatter around tex2html_wrap_inline5484 N from tex2html_wrap_inline5512 E to tex2html_wrap_inline5370 E. Both radars record double-peaked spectra in a region centered at tex2html_wrap_inline5680 N from about tex2html_wrap_inline5490 E to tex2html_wrap_inline5320 E. The locations of these spectra from both radars compare well.

Figure 5.52: Map of spectral findings from the Saskatoon and Kapuskasing radars: 20 Feb/95

As can be seen in Figure 5.53, the satellite passes right through the region where double-peaked spectra were found from tex2html_wrap_inline5686 to tex2html_wrap_inline5688 . It also crosses over the region of missing Kapuskasing backscatter from tex2html_wrap_inline5690 to tex2html_wrap_inline5692 as can be seen in Figure 5.52.

Figure 5.53: Peak-map with overlaid flight path of the DMSP F12 satellite: 20 Feb/95

Figure 5.54 shows relatively high fluxes during most of the track segment. The electron energy is highest from tex2html_wrap_inline5694 to tex2html_wrap_inline5696 corresponding to the region of missing backscatter. From tex2html_wrap_inline5698 to tex2html_wrap_inline5694 , which is the interval in which double-peaked spectra were found, the satellite recorded several high flux events at low electron energy.

Figure 5.54: Average electron energy and flux determined from SSJ/4 instrument measurements: 20 Feb/95

Figure 5.55 shows clearly that the region of high F-layer ionization corresponds exactly to the period in which double-peaked spectra were observed.

Figure 5.55: Estimated ionization rates at E- and F-layer heights determined from electron spectra measurements: 20 Feb/95

Figure 5.56 indicates the beginning of high E-layer conductivity to be at about tex2html_wrap_inline5690 matching exactly the beginning of missing Kapuskasing backscatter.

Figure 5.56: Estimated E-layer conductivities from the Robinson model: 20 Feb/95

The velocity map in Figure 5.57 shows that there is a strong shear in the region of westward convection centered at about tex2html_wrap_inline5704 latitude, which is the center of the region of double peaked spectra. Below tex2html_wrap_inline5326 N is a section of flow at very low velocities which are in a westward direction further south. An interesting feature is the presence of a large scale, morning sector convection vortex centered at about tex2html_wrap_inline5708 N and tex2html_wrap_inline4632 E. The vortex has upward vorticity so the field-aligned current is downward which is as expected, opposite to the upward FAC observed in afternoon vortices (Bristow et al., 1995).

Figure 5.57: SuperDARN velocity map: 20 Feb/95

next up previous
Next: 21 Feb/952:30 - Up: Morphology during a Complete Previous: 18 Feb/951:25 -

Andreas Schiffler
Wed Oct 9 10:05:17 CST 1996