Erlangen 2018 – scientific programme

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UP: Fachverband Umweltphysik

UP 8: Methods - measurement techniques; Atmosphere - trace gases, mesosphere

UP 8.6: Talk

Wednesday, March 7, 2018, 15:15–15:30, G 1.011

Wave driven dynamical processes to couple the lower and the middle atmosphere over the year — •Kathrin Baumgarten, Michael Gerding, and Franz-Josef Lübken — Leibniz-Institute of Atmospheric Physics at the University of Rostock , Kühlungsborn, Germany

Atmospheric waves, e.g., gravity and tidal waves, play a key role for our understanding of the circulation in the Earth's atmosphere. Due to the propagation and interaction of these waves, they couple different atmospheric layers from the troposphere to the mesosphere by the transport of momentum and energy over a wide range of scales. The propagation of gravity waves is strongly affected by tides as they modulate the mean background wind field. Since 2010 a daylight capable RMR lidar for high resolution density and temperature measurements at Kühlungsborn (54° N, 12° E) is in operation to investigate wave phenomena in the middle atmosphere between 30 and 75 km altitude. An extensive data set of about 7500 hours is used to derive the seasonal variation of different gravity and tidal waves. Therefore, a 1-dimensional spectral filtering technique is used to separate gravity and tidal waves. Inertia gravity waves and tides show a reduced activity during summer as theoretically expected due to the mean prevailing winds. Gravity waves with periods of only a few hours or less behave contrary to this. This is presumably caused by large horizontal phase speeds allowing these gravity waves to propagate into the mesosphere. We will present the seasonal variation of gravity waves as well as tides to demonstrate their particular influence in different regions of the middle atmosphere.