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The article presents a study which examines the wind measurements by the Rayleigh/Mie/Raman (RMR) and sodium lidar at the ALOMAR Observatory in Northern Norway. It is inferred that the RMR and sodium lidar is excellent for long integration times of 10 hours. Common volume wind measurements in the middle atmosphere using lidar instruments are outlined.

Noctilucent clouds (NLC) have been measured by the Rayleigh/Mie/Raman-lidar at the ALOMAR research facility in Northern Norway (69° N, 16° E). From 1997 to 2010 NLC were detected during more than 1850 h on 440 different days. Colocated MF-radar measurements and calculations with the Leibniz-Institute Middle Atmosphere (LIMA-) model are used to characterize the background atmosphere. Temperatures as well as horizontal winds at 83 km altitude show distinct differences during NLC observations compared to when NLC are absent. The seasonally averaged temperature is lower and the winds are stronger westward when NLC are detected. The wind separation is a robust feature as it shows up in measurements as well as in model results and it is consistent with the current understanding that lower temperatures support the existence of ice particles. For the whole 14-year data set there is no statistically significant relation between NLC occurrence and solar Lyman-a radiation. On the other hand NLC occurrence and temperatures at 83 km show a significant anti-correlation, which suggests that the thermal state plays a major role for the existence of ice particles and dominates the pure Lyman-α influence on water vapor during certain years. We find the seasonal mean NLC altitudes to be correlated to both Lyman-α radiation and temperature. NLC above ALOMAR are strongly influenced by atmospheric tides. The cloud water content varies by a factor of 2.8 over the diurnal cycle. Diurnal and semidiurnal amplitudes and phases show some pronounced year-to-year variations. In general, amplitudes as well as phases vary in a different manner. Amplitudes change by a factor of more than 3 and phases vary by up to 7 h. Such variability could impact long-term NLC observations which do not cover the full diurnal cycle. [ABSTRACT FROM AUTHOR]

Abstract: Between 1997 and 2007 noctilucent clouds (NLC) have been observed by the Arctic Lidar Observatory for Middle Atmosphere Research (ALOMAR) Rayleigh/Mie/Raman (RMR) lidar in Northern Norway at , . During a total of 3322 measurement hours, being well distributed over the 11 years, season and local time, NLC were detected for 1272h. The seasonal extreme values of NLC occurrence, altitude, brightness and vertical extent are found 15–30 days after summer solstice. The year-to-year occurrence frequency of strong NLC is anti-correlated to solar activity until 2004 and decreases monotonously thereafter. This drop in cloud occurrence is not seen by satellite-borne SBUV instruments and raises the question about the interpretation of cloud occurrences observed by different methods. The cloud water content is unchanged or even decreasing after 2004. Considering the entire 11 year period there is no significant anti-correlation between the occurrence of strong clouds and solar activity. The mean NLC altitudes are and for all clouds and strong clouds, respectively. Today''s cloud altitudes differ by only a few hundred meters from observations years ago (82.1km). Taking into account current geophysical cloud altitude variability of , the mean NLC altitude appears to be unchanged. This behavior falls short of an expected altitude decrease of more than 2km following from temperature trends calculated by current global atmosphere models. [Copyright &y& Elsevier]