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Ann. Geophys., 25, 9-12, 2007
www.ann-geophys.net/25/9/2007/
© European Geosciences Union 2007

Lunar tides in the Mesosphere over Ascension Island (8° S, 14.4° W)

D. J. Sandford and N. J. Mitchell
Centre for Space, Atmospheric & Oceanic Science, Department of Electronic and Electrical Engineering, University of Bath, Bath, BA2 7AY, UK

Abstract. A meteor radar has been used to measure the horizontal winds in the equatorial mesosphere and lower thermosphere over Ascension Island (8.0° S, 14.4° W). A 5-year data set covering the interval 2001–2005 over the height range 78–100 km is considered. The lunar M₂ tide is clearly evident in the data and reaches amplitudes as large as 11 ms⁻¹ in the meridional component and 6 ms⁻¹ in the zonal component. These are the first observations of the lunar tide made over the equatorial Atlantic sector. Comparisons of the observed seasonal behaviour with the model of Vial and Forbes (1994) reveals good agreement, but the observed amplitudes are generally larger and there is a systematic phase difference of ~2 h with the observed phases lagging the model. Comparisons with observations made at other equatorial sites suggest the presence of non-migrating lunar M₂ tides and/or significant inter-annual variability.

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Citation: Sandford, D. J. and Mitchell, N. J.: Lunar tides in the Mesosphere over Ascension Island (8° S, 14.4° W), Ann. Geophys., 25, 9-12, 2007.   Bibtex   EndNote   Reference Manager