Thermosphere/Ionosphere Gravity wave Effects Resulting from Upward Coupling (TigerUC)

热层/电离层（T/I）系统受到来自上方（太阳、地磁）和下方的强烈影响。下面最重要的过程之一是波（例如行星波、潮汐或重力波），它们主要在对流层/对流层顶区域激发。由于它们的垂直传播，这些波垂直耦合了T/I和中层大气。特别是，重力波（GWs）对这种耦合的贡献仍然知之甚少。其中一个原因是GWs的水平尺度很短（几十公里到几千公里），这对观测和模式都提出了挑战。我们将从多个卫星/卫星星座（SWARM， CHAMP， GOCE， GRACE）观测到的多个原位数据集（例如，中性和电子密度）中得出T/I中的GW分布。我们将推导出具有特征的全球分布，并确定最相关的时间变化（例如年周期、太阳周期）。这些GW分布将与卫星仪器HIRDLS和SABER在平流层和中间层的观测结果（GW方差、GW动量通量和GW阻力）进行比较。一些数据集（CHAMP、GRACE、SABER）的覆盖时间超过十年。研究了250 ~ 500km高度T/I的GW分布与整个20 ~ 100km高度中层大气（平流层/中间层）GW分布的时空相关性。根据这些相关性，可以得到在T/I观测到的中层大气中哪些高度和区域对时空变化贡献最大的信息。特别是，HIRDLS和SABER对GW阻力的独特观测可以进一步证明，从强GW耗散区域发射的二次GW是否对T/I观测到的全球GW分布有重要贡献。此外，从现场观测中，我们将尝试推导出T/I区域的GW动量通量和GW阻力。这些数据集对于直接比较T/I地区一般环流模式（GCMs）模拟的GW分布特别重要。这些模拟的GW分布需要正确地模拟GW对T/I中背景气流的阻力。这仍然是T/I区域模式的主要不确定因素之一，因为到目前为止，通过观测来验证这些模式分布仍然是一个悬而未决的问题。

The thermosphere/ionosphere (T/I) system is strongly influenced from above (solar, geomagnetic), as well as from below. One of the most important processes from below are waves (e.g. planetary waves, tides, or gravity waves) that are mostly excited in the troposphere/tropopause region. Due to their vertical propagation, these waves are vertically coupling the T/I and the middle atmosphere. In particular, the contribution of gravity waves (GWs) to this coupling is still poorly understood. One of the reasons is the short horizontal scale of GWs (a few ten km to several thousand km) that challenges both observations and models.We will derive GW distributions in the T/I from multiple in situ data sets (e.g., both neutral and electron densities) observed by several satellites/satellite constellations (SWARM, CHAMP, GOCE, GRACE). Characteristic global distributions will be derived, and we will identify the most relevant temporal variations (e.g. annual cycle, solar cycle). These GW distributions will be compared with observations of the satellite instruments HIRDLS and SABER (GW variances, GW momentum fluxes and GW drag) in the stratosphere and mesosphere. Several of the data sets (CHAMP, GRACE, SABER) cover more than ten years. Spatial and temporal correlations between the GW distributions in the T/I at altitudes 250-500km and GW distributions in the middle atmosphere (stratosphere/mesosphere) over the whole altitude range 20-100km will be investigated. Based on these correlations, information shall be obtained, which altitudes and regions in the middle atmosphere contribute most to temporal and spatial variations observed in the T/I. In particular, the unique observations of GW drag from HIRDLS and SABER can provide further evidence whether secondary GWs presumably emitted from regions of strong GW dissipation contribute significantly to the global GW distributions observed in the T/I.Further, from the in situ observations, we will attempt to derive GW momentum fluxes and GW drag in the T/I region. Such data sets are particularly important for direct comparison with GW distributions that are simulated by general circulation models (GCMs) in the T/I region. These modeled GW distributions are required to properly simulate the drag that GWs exert on the background flow in the T/I. This is still one of the main uncertainties in the modeling of the T/I region as, up to now, validation of these model distributions by observations is still an open issue.