MIDDLE ATMOSPHERE (60-110 KM) TIDAL OSCILLATIONS AT SASKATOON, CANADA (52-DEGREES-N, 107-DEGREES-W) DURING 1983-1984

Winds have been measured by a medium frequency radar using the spaced antenna method, in the upper middle atmosphere (60-110 km). The mean or prevailing winds are related to the seasonal variation of the semidiurnal and diurnal tide, as inferred as Saskatoon by the amplitude and phase of the 12- and 24-hour wind oscillations. Strong seasonal variations are evidenced, consistent with the importance of antisymmetric tidal modes (2, minus 3; 2, minus 5; and 1, minus 1, respectively). For both tides, winter wavelengths are shorter than summer; the semidiurnal tide dominates the winter months, but in summer the diurnal tide has its maximum. The fluctuations and trends in winds and tidal oscillations during the stratospheric warming and the spring equinox are discussed.