Phase velocity studies of 34-cm E-region irregularities observed at Millstone Hill
Abstract
Phase velocity observations at E-region heights made with the Millstone Hill 440 MHz radar find no evidence of an ion acoustic limiting speed for phase speeds observed near 0 deg magnetic aspect angle. Under most circumstances the phase speed increases steadily with increasing backscattered power amplitude. For a 34 cm volume backscatter cross-section, less than about 5 x 10 exp -13/m, the phase speed is at or below the usual ion acoustic speed in the E-region (350 m/s), and increases only slowly with the observed backscattered power amplitude (about 50 m/s per 10 dB). At higher power levels, the phase speed exceeds 350 m/s, reaching values in excess of 750 m/s at times, and increases more rapidly with backscattered power (about 200 m/s per 10 dB). Phase velocity/time maps observed over a 3-deg span of latitude suggest that many features of the phase speeds observed are directly related to changes in the ambient convection electric field in the E-region due to changing activity conditions or the effects of superimposed magnetospheric pulsations.
- Publication:
-
Journal of Atmospheric and Terrestrial Physics
- Pub Date:
- June 1992
- DOI:
- 10.1016/0021-9169(92)90114-Z
- Bibcode:
- 1992JATP...54..759F
- Keywords:
-
- Backscattering;
- E Region;
- Earth Magnetosphere;
- Incoherent Scatter Radar;
- Phase Velocity;
- Autocorrelation;
- Eiscat Radar System (Europe);
- Ion Acoustic Waves;
- Radar Measurement