Noctilucent clouds (NLC) are an excellent tracer for processes in the upper mesosphere. The clouds consist of ice particles whose existence sensitively depends on ambient temperature and water vapor content. Both parameters are hard to measure directly with high accuracy. Therefore NLC are used to characterize changes of the mean state as well as the dynamics in the mesopause region. The daily cyclic absorption of solar energy by the atmosphere causes thermal tides which are detected in various atmospheric parameters like temperature, density, winds, and NLC.
The influcence of the lunar gravitation on the atmosphere has been identified in surface air pressure already more than 170 years ago. Since then lunar tidal signatures were found in several parameters even in the upper mesosphere. However, studies on lunar tidal influences on NLC are
very limited and the results are partly contradictory. The lunar signal is presumably small compared to the solar signal and hence it needs a large database for identification. Only recently the lunar semidiurnal tide was found in satellite observations of NLC by SBUV instruments.

The ALOMAR RMR-lidar, located at 69°N, started operation in 1994 and covers by now 2990 hours NLC detections during 6230 measurement hours within 23 seasons. This dataset contains variabilities of basic cloud parameters like occurrence, altitude and brightness on time scales ranging from minutes to years. NLC above ALOMAR are strongly influenced by solar tides, e.g. the clouds occur twice as often per hour during the morning than during the rest of the day, and the cloud altitude shows mean variations of about 1 km in the course of the day. Now the
dataset was investigated for the first time regarding lunar tidal signatures. We will present results obtained by the superposed epoch analysis method, showing a lunar impact on NLC occurrence frequency and altitude.