Articles | Volume 18, issue 12
31 Dec 2000
31 Dec 2000

Lunar tidal winds in the upper atmosphere over Collm

R. J. Stening and C. Jacobi

Abstract. The lunar semidiurnal tide in winds measured at around 90 km altitude has been isolated with amplitudes observed up to 4 m s–1. There is a marked amplitude maximum in October and also a considerable phase variation with season. The average variation of phase with height indicated a vertical wavelength of more than 80 km but this, and other results, needs to be viewed in the light of the considerable averaging required to obtain statistical significance. Large year-to-year variations in both amplitude and phase were also found. Some phase comparisons with the GSWM model gave reasonable agreement but the model amplitudes above a height of 100 km were much larger than those measured. An attempt to make a comparison with the lunar geomagnetic tide did not yield a statistically significant result.

Key words: Meteorology and atmospheric dynamics (middle atmosphere dynamics; waves and tides)