A daylight capable Rayleigh-Mie-Raman (RMR) lidar is in operation since summer 2010 at the mid-latitude station Kühlungsborn (54° N, 12° E). The RMR lidar system is used for measuring temperature profiles during day and night. The soundings are intended for investigation of short and long periodic atmospheric waves, like gravity waves (GW) and thermal tides (with diurnal, semidiurnal and terdiurnal components) in the altitude range between ~30 and ~70 km. About 6150 h of data have been acquired so far; with each sounding lasting for at least 6 h. If temperature deviations from the daily mean are averaged synchronous to local time, gravity wave signatures are suppressed and monthly mean tidal parameters can be derived even from an interrupted data set. Uninterrupted observations covering up to five days and nights allow the calculation of tidal amplitudes on a much shorter scale. We will present different case studies of multi-day lidar soundings and demonstrate the large tidal variability even on a day-to-day basis. The superposition of GW, tides or even longer periodic waves in time series of temperature profiles always implies some ambiguity for GW analysis. Especially short period GW can at least partly hide behind tidal temperature deviations if only deviations from the daily mean are examined. Therefore we use different spectral filter methods for extracting GW induced temperature fluctuations. We will demonstrate that the gravity wave potential energy density (GWPED) strongly depends on the used filter method. First results on the seasonal variation of frequency resolved GWPED are presented.

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*email: gerding@iap-kborn.de
*Preference: