Lidar observations of temperatures, waves, and noctilucent clouds at 69° N

The ALOMAR Rayleigh/Mie/Raman (RMR) lidar is an active remote sensing instrument for the investigation of the Arctic middle atmosphere during day and night. It is located in Northern Norway and operated on a routine basis to measure relative density profiles and aerosol properties in the stratosphere and mesosphere since 1995. Temperature profiles derived from the density measurements assuming hydrostatic equilibrium are used to investigate the mean temperature structure as well as gravity waves in the polar middle atmosphere. During the last two years, temperature data were acquired for approximately 2100 hours. A subset of this data basis was used to determine the potential energy density to characterize the gravity wave activity above the station. Noctilucent clouds (NLC) are the highest clouds of the Earth's atmosphere and a visible sign of extreme atmospheric conditions with temperatures far below radiative equilibrium. During the last 7 years a continuous data set with 1880 measurement hours was acquired during the summer seasons, of which 640 hours contain NLC signatures. This actually most extensive lidar acquired NLC archive was analyzed regarding brightness, altitude, vertical extent, as well as occurrence frequency of noctilucent clouds above ALOMAR.