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)以及下方的强烈影响。从下面开始的最重要的过程之一是主要在对流层/对流层顶区域激发的波(例如行星波、潮汐或重力波)。由于它们的垂直传播，这些波在垂直方向上耦合了T/I和中间大气。特别是，重力波(GW)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)，这对观测和模型都构成了挑战。我们将从几个卫星/卫星星座(SWARM、CHAMP、GOCE、GRACE)观测的多个现场数据集(例如，中性密度和电子密度)得出T/I中的GW分布。我们将得出特征的全球分布，并确定最相关的时间变化(例如，年度周期、太阳周期)。这些GW分布将与卫星仪器HIRDLS和SABER(GW方差、GW动量通量和GW阻力)在平流层和中间层的观测结果进行比较。有几个数据集(冠军、格蕾丝、军刀)涵盖了十年以上的时间。我们将研究250-500公里高度T/I的GW分布与整个高度20-100公里的中层(平流层/中间层)GW分布之间的时空相关性。根据这些相关关系，可以得到哪些高度和区域对T/I中观测到的时间和空间变化的贡献最大。特别是，HIRDLS和SABER对GW阻力的独特观测可以提供进一步的证据，证明从强GW耗散区域发射的次生GW是否对T/I中观测到的全球GW分布有显著贡献。此外，我们将尝试从现场观测中得出T/I区的GW动量通量和GW阻力。这样的数据集对于直接与T/I地区的大气环流模式(GCM)模拟的GW分布进行比较特别重要。这些模拟的GW分布是正确模拟GW对T/I中背景气流施加的阻力所必需的。这仍然是T/I区域模拟中的主要不确定性之一，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.