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Ann. Geophys., 26, 1221-1232, 2008
www.ann-geophys.net/26/1221/2008/
© European Geosciences Union 2008

Trends in MLT region winds and planetary waves, Collm (52° N, 15° E)

Ch. Jacobi¹, P. Hoffmann¹, and D. Kürschner^2
1Institute for Meteorology, University of Leipzig, Stephanstr. 3, 04103 Leipzig, Germany
²Faculty of Physics and Earth Sciences, University of Leipzig, Collm Observatory, 04779 Wermsdorf, Germany

Abstract. Long-period oscillations in the period range 2–30 days, interpreted as planetary wave (PW) signatures, have been analysed using daily mesosphere/lower thermosphere wind measurements near 90 km over Collm (52° N, 15° E) in the time interval 1980–2005. Interannual and interdecadal variability of PW are found. Since the 1990s, a tendency for larger zonal amplitudes compared to meridional ones has been observed, i.e. some long-term trends are visible, which are positive in the zonal component, but negative in the meridional component. There is a tendency of the trend to be non-linear for waves with periods lower than 7 days, so that a climatic transition appears around 1990, with smaller changes before and after that time. A solar cycle effect on PW is weak, but there is a tendency for a positive correlation between solar flux and wave activity, if a time lag of PW activity with respect to the solar flux of about 2 years is taken into consideration.

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Citation: Jacobi, Ch., Hoffmann, P., and Kürschner, D.: Trends in MLT region winds and planetary waves, Collm (52° N, 15° E), Ann. Geophys., 26, 1221-1232, 2008.   Bibtex   EndNote   Reference Manager