Lunar tidal winds in the upper atmosphere over Collm

C. Jacobi,R. J. Stening

doi:10.1007/s005850000310

Abstract

Abstract. The lunar semidiurnal tide in winds measured at around 90 km altitude has been isolated with amplitudes observed up to 4 m sâ1. 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)

Highlights

The lunar atmospheric tide is generated in the lower atmosphere primarily as a result of the moon's gravitational attraction on the atmosphere and of the vertical motion of the oceans at the lower boundary of the atmosphere
The lunar semidiurnal tide in winds measured at around 90 km altitude has been isolated with amplitudes observed up to 4 m s
In order to understand the lunar geomagnetic variations we needed to study the lunar tides in the winds which drive these variations by dynamo action in the ionosphere

Summary

Introduction

The lunar atmospheric tide is generated in the lower atmosphere primarily as a result of the moon's gravitational attraction on the atmosphere and of the vertical motion of the oceans at the lower boundary of the atmosphere. The lunar semidiurnal tide in winds measured at around 90 km altitude has been isolated with amplitudes observed up to 4 m s)1. 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.

Results

Conclusion