Mesospheric Metal Layer Dynamics

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The region of the upper mesosphere and lower thermosphere (MLT) between approximately 70 km and 120 km altitude shows a variety of unique physical and chemical processes, such as the lowest temperatures of the atmosphere, the ablation of meteors creating metal layers, or the occurrence of the Earth’s highest clouds (noctilucent clouds) which are discussed as indicators of anthropogenic climate change. The MLT’s dynamics are not yet fully understood but can deliver important insights into the whole atmosphere system, in particular through a better understanding of gravity waves which deposit significant amounts of energy and momentum and couple different atmospheric layers. A particular challenge are accurate measurements in this remote altitude range, especially on short timescales. Recent developments in lidar technology allow to observe dynamic features in mesospheric metal layers continuously present in the MLT. However, these metal layers undergo a variety of temperature-dependent chemical reactions and are therefore no passive tracers for dynamic processes.The overall goal of this project is to quantitatively examine and understand the influence of dynamic atmospheric processes on meteoric metal layers in the altitude region between 70 and 120 km, in particular on short timescales. With the parameters derived from the analysis of a newly developed atmospheric chemistry model, dynamic features such as gravity waves and tides can then be decomposed from lidar observations of metal layers. This will allow to use available high-resolution atom density observations to analyse various dynamic phenomena such as gravity waves at unprecedented temporal scales. This goal will be achieved by a) investigating the influence of atmospheric dynamics on mesospheric metal layers with an improved atmospheric chemistry model, b) coupling this metal layer chemistry model with a high-resolution atmospheric dynamic model, and c) comparing model simulations with available data sets of metal layer lidar observations. The expected results are of high importance for the understanding of the MLT and its role in the global atmosphere.