SEASONAL VARIATION OF SOUTHERN HEMISPHERE MID-LATITUDE WINDS AT ALTITUDES OF 70-100 KM

The spaced receiver method of measuring ionospheric drifts was used to investigate atmospheric motion between 65 and 100 km at 44°S lat. Techniques and limitations are discussed. The preliminary results, taken between December 1963 and November 1964, mostly around noon, provide a good estimate of the monthly mean zonal wind. The meridional component appears too high, possibly because the restricted observing schedule did not permit a complete removal of the tidal components. The winter zonal component changes from eastward to westward above a height which varies from 80 km in April to 100 km in July. There are indications of a mid-winter (late July) warming between 80 and 100 km. In December (summer) the zonal winds are westward throughout the observable range (70-95 km). © 1968.