Atmos. Chem. Phys. Discuss., 9, 10271-10301, 2009
© Author(s) 2009. This work is distributed
under the Creative Commons Attribution 3.0 License.
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This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
The two-day wave in the Antarctic and Arctic mesosphere and lower thermosphere
V. M. Tunbridge and N. J. Mitchell
Department of Electronic and Electrical Engineering, University of Bath, Bath, UK

Abstract. There have been comparatively few studies reported of the 2-day planetary wave in the middle atmosphere at polar latitudes. Here we report studies made using high-latitude meteor radars at Rothera in the Antarctic (68° S, 68° W) and Esrange in Arctic Sweden (68° N, 21° E). Observations from 2005–2008 are used for Rothera and from 1999–2008 for Esrange. Data were recorded for heights of 80–100 km. The radar data reveal distinct summertime and wintertime 2-day waves. The Antarctic summertime wave occurs with significant amplitudes in January–February at heights between about 88–100 km. Horizontal wind monthly variances associated with the wave exceed 160 m2 s−2 and the zonal component has larger amplitudes than the meridional. In contrast, the Arctic summertime wave occurs for a longer duration, June–August and has meridional amplitudes larger than zonal. The Arctic summertime wave is weaker than that in the Antarctic and maximum monthly variances are typically 60 m2 s−2. In both hemispheres the summertime wave reaches largest amplitudes in the strongly sheared eastward zonal flow above the zero wind line and is largely absent in the westward flow below. The observed differences in the summertime wave is probably due to the differences in the background zonal winds in the two hemispheres. The Antarctic and Arctic wintertime waves have very similar behavior. The Antarctic wave has significant amplitudes in May–August and the Arctic wave in November–February. Both are evident across the full height range observed.

Citation: Tunbridge, V. M. and Mitchell, N. J.: The two-day wave in the Antarctic and Arctic mesosphere and lower thermosphere, Atmos. Chem. Phys. Discuss., 9, 10271-10301, doi:10.5194/acpd-9-10271-2009, 2009.
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