Analyzing the Motion of the Middle Atmosphere Using Nighttime RMR-lidar Observations at the Midlatitude Station Kühlungsborn (AMUN)

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Horizontal wind plays a key role in the dynamics of the atmosphere in general, and specifically for the propagation and dissipation of gravity waves and thermal tides. Simultaneous observations of winds and temperatures offer the unique possibility to retrieve both gravity wave kinetic and potential energy densities, being related by intrinsic wave properties. However, direct wind observations in the middle atmosphere are sparse especially between about 30 and 75 km, because neither radiosondes nor radars cover this altitude range. Wind radiometers or satellites do not provide wind information with sufficient accuracy and resolution for gravity wave investigations. Thus, we propose to set up a new lidar at Kühlungsborn/Germany (54°N, 12°E) to measure the horizontal wind by detecting the Doppler shift of Rayleigh backscatter using tilted telescopes. Beside climatological wind measurements, especially the propagation of inertia gravity waves in the middle atmosphere will be evaluated. We will calculate horizontal and vertical momentum fluxes and identify the altitudes of their deposition. These are crucial parameters for the energy budget of the atmosphere, and our results will provide a benchmark for general circulation models. Based on the wind data we will analyze hodographs to get intrinsic wave properties otherwise hidden for ground-based observers. We will separate the waves by vertical propagation direction and quantify the fraction of upward and downward propagating gravity waves, which requires local wind data to identify the Doppler shift of the wave’s phases. These analyses will deepen our understanding of the vertical coupling and of the underlying circulation in the middle atmosphere. This new wind lidar at Kühlungsborn complements a similar system operated by IAP in Northern Norway (ALOMAR, 69°N, 16°E). We will make use of the expertise developed for the ALOMAR lidar to reduce the design risks for the new lidar, and to foster wind measurements in the middle atmosphere as well as geophysical interpretation of the observations.