Mesospheric Metal Layer Dynamics

大约70公里至120公里高度之间的上层中间层和下层热层(MLT)区域显示了各种独特的物理和化学过程，例如大气的最低温度、形成金属层的流星的消融或地球上最高的云(夜光云)的出现，这些云被认为是人为气候变化的指标。目前尚未完全了解MLT的动力学，但可以对整个大气系统提供重要的见解，特别是通过更好地了解重力波，重力波沉积了大量的能量和动量，并耦合了不同的大气层。一个特别的挑战是在这个偏远的海拔范围内进行准确的测量，特别是在短时间尺度上。激光雷达技术的最新发展使得能够观测MLT中持续存在的中间层金属层的动态特征。然而，这些金属层经历了各种依赖温度的化学反应，因此不是动态过程的被动示踪剂。这个项目的总体目标是定量地检查和了解动态大气过程对海拔70至120公里区域的大气流星层的影响，特别是在短时间尺度上。根据新开发的大气化学模型的分析得出的参数，可以从激光雷达对金属层的观测中分解出重力波和潮汐等动力学特征。这将使人们能够利用现有的高分辨率原子密度观测，在前所未有的时间尺度上分析各种动态现象，如重力波。这一目标将通过以下方式实现：a)利用改进的大气化学模式调查大气动力学对中间层金属层的影响，b)将该金属层化学模式与高分辨率大气动力学模式相结合，c)将模型模拟与现有的金属层激光雷达观测数据集进行比较。预期结果对于理解多边贸易条约及其在全球大气层中的作用具有重要意义。

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.