Investigation of geomagnetic influences on the vertical coupling by gravity waves in the thermosphere/ionosphere

垂直传播重力波(GWS)是连接低层大气和热层/电离层(TI)系统的主要耦合机制。全球变暖是地球气候的重要组成部分。其中很大一部分起源于对流层，并在传播和消散时在大气层之间重新分配能量和动量。在TI中，分子粘度和离子阻力是GWS的主要耗散机制。TI中磁场的变化改变了大气的折射特性(大尺度温度和风的分布)，并通过离子阻力改变了耗散。这项研究的主要目的是研究和量化地磁场的变化对低层大气起源的GW的传播和耗散及其对TI的动力反馈的影响。特别是，将测试GWS的作用，将地磁场减弱的趋势与观测到的无法解释的热层冷却联系起来。这项研究将使用一个综合耦合的中-热大气-2(CMAT2)大气环流模式进行，该模式利用了我们最先进的谱非线性GW参数化。将进行新的数值模拟，并根据现有和未来的观测数据集，包括来自集群卫星的数据，对结果进行测试。除了推进和测试我们对GW耦合的基本理解外，这些结果还可能改善空间天气预报。

Vertically propagating gravity waves (GWs) represent a major coupling mechanism that provides connections between the lower atmosphere and thermosphere/ionosphere (TI) system. GWs are an essential component of the climate of Earth. A large portion of them originate in the troposphere, and redistribute energy and momentum between the atmospheric layers upon propagation and dissipation. In the TI, molecular viscosity and ion drag are the major dissipation mechanism of GWs. Variations of the magnetic field in the TI change the refractive properties of the atmosphere (large-scale temperature and wind distributions), and alter dissipation by ion drag. The primary objective of this study is to investigate and quantify the influence of variations of the geomagnetic field on propagation and dissipation of GWs of lower atmospheric origin, and on their dynamical feedback on the TI. In particular, the role of GWs will be tested in linking a trend of weakening the geomagnetic field, and the unexplainably strong observed cooling of the thermosphere. The study will be performed using a comprehensive Coupled Middle Atmosphere-Thermosphere-2 (CMAT2) general circulation model that utilizes our state-of-the-art spectral nonlinear GW parameterization. Novel numerical simulations will be performed, and the results tested against existing and future observational datasets, including those from the SWARM satellites. Besides advancing and testing our fundamental understanding of the GW coupling, the results can potentially improve space weather predictions.