Angle-of-arrival oscillations in the mesosphere as seen by medium frequency (MF) radar
Abstract
The Saskatoon MF radar operates continuously in the spaced antenna mode with 5 min resolution, primarily for horizontal wind analysis at mesospheric heights. Mean Doppler frequency and antenna-pair phase difference are available as byproducts. Clear oscillations are sometimes seen in the latter. Spectral analysis shows that these also occur in the Doppler and extend over a range of heights. The two cases shown are almost certainly perturbations in specular reflecting layers moving with horizontal velocity close to that of the wind. Downward phase propagation is apparent, and when the oscillations are present, the wind appears to be decelerating. The tentative explanation of a breaking gravity wave decelerating the mean flow is put forward, although the relations between frequency, and horizontal and vertical wavelengths, contradict linear gravity wave theory.
- Publication:
-
Journal of Atmospheric and Terrestrial Physics
- Pub Date:
- April 1992
- DOI:
- 10.1016/0021-9169(92)90008-9
- Bibcode:
- 1992JATP...54..277M
- Keywords:
-
- Doppler Radar;
- Electromagnetic Wave Transmission;
- Gravity Waves;
- Ionospheric Disturbances;
- Mesosphere;
- Brunt-Vaisala Frequency;
- Power Spectra;
- Wind (Meteorology)