| description abstract | Winds and temperatures to above 80 km. measured during the International Geophysical Year by grenade, sphere accelerometer, and Pitot-static tube experiments at Churchill, Manitoba are combined with radiosonde data in time sections. The resulting analyses are discussed in reference to 10-mb. constant pressure charts showing the horizontal circulation near the 30-km. level. Periods in July, August, and December 1957 and January?February 1958 are covered. The nature of the circulation in successive layers of the stratosphere and mesosphere is suggested by this investigation. In summer, irregular wind flow that is predominantly from the east appears in the middle and upper stratosphere. Strong easterlies in the lower and middle mesosphere are bounded in the upper mesosphere above 75 km. by a sharp vertical wind shear layer with highly variable west winds above, suggesting the existence of rapidly moving, intense cellular circulations near the mesopause. In winter when the boundary of the polar night is close to Churchill, such circulations seem to extend into lower layers until in January they occupy the entire mesosphere. Strong west winds develop in the mid-stratosphere of wintertime, and a temperature minimum appears near the 30-km. level. During January 1958 the strong westerlies and the temperature minimum as well were disrupted by sudden warming of the entire stratosphere. The vertical structure of this warming effect, as it moved westward across the Atlantic and first appeared at the 40-km. level aver Churchill, is shown by means of a cross section. | |
