The 16-day variation in the mean flow at Grahamstown (33.3° S, 26.5° E)

S. B. Malinga (1) , L. M. G. Poole (1)

1 Department of Physics-Electronics

Data from the Grahamstown (33.3° S, 26.5° E) meteor radar have been used to study the short-term variations of the mean flow at ~ 90 km altitude. The results show considerable variation characterised by a superposition of fluctuations on different planetary time scales. Wavelet multi-resolution and spectral techniques reveal that the quasi-16-day oscillation dominates the wave spectrum in the ~ 2?20-day period range. This quasi-16-day oscillation, which is thought to be related to a similar oscillation in the lower atmosphere, is found to be dominant in winter and the equinoxes. However, it is sometimes significant in summer, which could be due to cross-equatorial ducting and the selective transmissivity of gravity waves.

Domaines: Océan, Atmosphère; Sciences de la Terre

S. B. Malinga, L. M. G. Poole. The 16-day variation in the mean flow at Grahamstown (33.3° S, 26.5° E). Annales Geophysicae, 2002, 20 (12), pp.2027-2031. ⟨hal-00317455⟩