Upper-Atmosphere Zonal Winds: Variation with Height and Local Time.
Abstract
The average rotation rate of the upper atmosphere can be found by analysis of the changes in the orbital inclinations of satellites, and results previously obtained have indicated that the atmospheric rotation rate appreciably exceeds the Earth's rotation rate at heights between 200 and 400km. This report examines all such results previously published in the light of current standards of accuracy: some are accepted, some revised, and some rejected as inadequate in accuracy. Also analysed are a number of fresh orbits and, adding these to the accepted and revised previous results, the variation of zonal wind speed with height and local time is derived. The rotation rate (rev/day) averaged over all local times increases from near 1.0 at 150km height to 1.3 near 350km (corresponding to an average west-to-east wind of 120km/s), and then decreases to 1.0 at 400km and probably to about 0.8 at greater heights. The maximum west-to-east winds occur in the evening hours, 18-24h local time: these evening winds increase to a maximum of about 150m/s at heights near 350km and decline to near zero around 600km. In the morning, 4-12h local time, the winds are east to west, with speeds of 50-100m/s above 200km. It is also tentatively concluded that, at heights above 350km, the average rotation rate is greater in equatorial latitudes (0-25 deg) than at higher latitudes. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- May 04, 1976
- Accession Number
- ADA032255
Entities
People
- Desmond King-Hele
- Doreen Walker
Organizations
- Royal Aircraft Establishment