Meteor radar quasi 2-day wave observations over 10 years at Collm (51.3°N, 13.0°E)

The quasi 2-day wave (QTDW) at 82-97 km altitude over Collm (51 degrees N, 13 degrees E) has been observed using a VHF meteor radar. The long-term mean amplitudes calculated using data between September 2004 and August 2014 show a strong summer maximum and a much weaker winter maximum. In summer, the meridional amplitude is slightly larger than the zonal one with about 15 m s(-1) at 91 km height. Phase differences are slightly greater than 90 degrees on an average. The periods of the summer QTDW vary between 43 and 52 h during strong bursts, while in winter the periods tend to be more diffuse. On average, the summer QTDW is amplified after a maximum of zonal wind shear which is connected with the summer mesospheric jet and there is a possible correlation of the summer mean amplitudes with the background wind shear. QTDW amplitudes exhibit considerable inter-annual variability; however, a relationship between the 11-year solar cycle and the QTDW is not found.