Winds and Wave Motions to 110 km at Mid-Latitudes. V. An Analysis of Data from September 1974–April 1975

Abstract

The behavior of the daily noon winds at 52°N, 107° W (Saskatoon, Canada) at altitudes from 52 km to about 110 km are studied for the interval September 1974–Apzil 1975. These data are compared with ROCOB temperatures and winds (≲55 km) for Churchill (94°N, 59°W). The thermal wind equation and running cross-correlation analysis are used to demonstrate the seasonal variations of the meridional temperature gradient, and of coupling, within the stratosphere, mesosphere and thermosphere. The effects of the stratospheric warming of January 1975 are also investigated. The correlations were dominated by this event, and show that coupling occurred between the stratosphere (20–30 mb) and mesosphere/thermosphere (≲100 km) during the first half of January. Spectral analysis for two intervals before and after the stratwarm show that coupling was more significant during the late winter; periods near 2–3, 4–5 and ≳20 days were involved. Comparisons between daily mean winds and daily noon winds show that up to 100 km the daily variations are well represented by the noon data; above 100 km the daily variations are less reliable but trends are well represented by the noon data.