Winds and Wave Motions to 110 km at Mid-Latitudes. II. Mean Winds at 52°N, 1969–73

Abstract

The results of radiowave partial reflection wind (drift) observations, 62?116 km, for the years 1969?73, at 52°N, 107°W (Saskatoon), are presented, and are compared with current empirical models. Agreement is satisfactory to 85 km; but at higher altitudes, differences exist; notably an annual variation of zonal flow above 100 km, whose direction is eastward in summer and westward in winter. The semi-annual variation of winds is shown to be limited to 85?100 km, and is considered to be due to two out-of-phase annual variations identifiable at higher and lower altitudes. A region of positive (poleward) temperature gradient (high-latitude warming) is identified in the range ?80 to at least 107 km in winter, and another region (?75 to ?107 km) of negative temperature gradient is identified in summer. The relationships of these regions to circulation characteristics are discussed.