Ten hours of coherent scatter radar data were collected near 150-km altitude above Jicamarca, Peru, on July 27, 1977. The antenna system probed three separate volumes horizontally separated by approximately 9 km at 150 km. Measured vertical velocity varied between 10 and 20 m/s and is similar to the vertical ionization drift at these altitudes. However, the vertical velocity may change as much as 6 m/s over a 4-km height interval. Ten-minute amplitude modulations in the scattered power are seen throughout the observation period and are probably related to evanescent gravity waves. Several layers of enhanced scattering are observed at times. The half width of the measured spectra varies between 1 and 3 Hz with the vertically pointing antenna showing a consistently broader spectrum than the other two antennas. This narrow spectral width indicates a nonthermal scattering owing to electron density fluctuations. |