Abstract. Recent studies have shown that day-to-day variability of the migrating semidiurnal solar (SW2) tide within the mesosphere and lower thermosphere (MLT) is a key driver of anomalies in the thermosphere–ionosphere system. Here, we study the variability in both the amplitude and phase of SW2 using meteor radar wind and lidar temperature observations at altitudes of 75–110 km as well as wind and temperature output from the Navy Global Environmental Model – High Altitude (NAVGEM-HA), a high-altitude meteorological analysis system. Application of a new adaptive spectral filter technique to both local radar wind observations and global NAVGEM-HA analyses offers an important cross-validation of both data sets and makes it possible to distinguish between migrating and non-migrating tidal components, which is difficult using local measurements alone. Comparisons of NAVGEM-HA, meteor radar and lidar observations over a 12-month period show that the meteorological analyses consistently reproduce the seasonal as well as day-to-day variability in mean winds, mean temperatures and SW2 features from the ground-based observations. This study also examines in detail the day-to-day variability in SW2 during two sudden stratospheric warming, events that have been implicated in producing ionospheric anomalies. During this period, both meteor radar and NAVGEM-HA winds show a significant phase shift and amplitude modulation, but no signs of coupling to the lunar tide as previous studies have suggested. Overall, these findings demonstrate the benefit of combining global high-altitude meteorological analyses with ground-based observations of the MLT region to better understand the tidal variability in the atmosphere.

The daylight‐capable Rayleigh‐Mie‐Raman (RMR) lidar at the midlatitude station in Kühlungsborn (54°N, 12°E) is in operation since 2010. The RMR lidar system is used to investigate different fractions of atmospheric waves, like gravity waves (GW) and thermal tides (with diurnal, semidiurnal, and terdiurnal components) at day and night. About 6150 h of data have been acquired until 2015. The general challenge for GW observations is the separation of different wave contributions from the observed superposition of GW, tides, or even longer periodic waves. Unfiltered lidar data always include such a superposition. We applied a Butterworth filter to separate GW and tides by vertical wavelength with a cutoff wavelength of 15 km and by observed periods with a cutoff period of 8 h. GW activity and characteristics are derived in an altitude range between 30 and 70 km. The retrieved vertically filtered temperature deviations contain GW with small vertical wavelengths over a broad range of periods, while only a small range of periods is included in the temporally filtered temperature deviations. We observe an annual variation of the wave activity for unfiltered and vertically filtered data, which is caused from tides and inertia gravity waves. In contrast to that, filtering in time leads to a weak semiannual variation for gravity waves with periods of 4–8 h, especially in higher altitudes. During summer, these waves have the half of the total amount of the potential energy budget compared to the unfiltered data. This shows the importance of waves with periods smaller than 8 h.