Non-stationary Gravity Wave retrievals for GLORIA

重力波（GWs）是平流层和中间层全球环流模式的重要驱动因素。经常讨论的是由喷流和锋面激发的gw或由地形上的气流激发的gw。在理想化的模型研究中，很容易将两个不同的源分离开来，但对于观测波来说，这就比较困难了。我们建议在SouthTRAC运动期间使用大气辐射成像Gimballed Limb observatory （GLORIA）观测GW，使用简单的光谱GW模型进行GW物理限制的检索，通过不同的相位速度分离不同的波包，并通过射线追踪方法研究这些波的起源。具体包括以下几个步骤：为了研究对流层上层和平流层下层的GW，我们将在HALO的腹舱中部署GLORIA，进行GW定向研究飞行。我们利用反演模型的方法，从测得的辐射量推导出大气温度和痕量物质的三维分布。由于获得层析测量需要时间，目前这要求温度场几乎是静止的。为了克服这一限制并研究非平稳GW，我们将通过在正演模型中加入谱GW模型来扩展反演。目的是直接获取重力波参数。通过使用内置的重力波模型来模拟假设波的垂直传播，我们实现了状态向量的大幅减少，从而获得了更稳定的检索。这种减少将允许我们在状态向量中也包括非零的地面频率。根据结果，可以重建不同天气时间步长的三维温度场。在检索中推断的GWs的谱表示可以用来分离与不同源相关的不同相速度。该技术可以应用于同一高度、同一时域或同一地区的不同波的叠加。在即将到来的SouthTRAC活动中，将获得复杂大气情况的多仪器测量数据，以在广泛的高度范围内观测来自不同来源的GWs。这为研究这些波的分离程度提供了机会，理想情况下，还可以研究这些gw是否相互作用以及如何相互作用。博士项目包括三个主要的工作包来实现这一目标。首先，需要与亚琛工业大学数学系合作，充分开发层析反演方法。它的能力和局限性将使用合成和模型数据进行彻底调查。第二个工作包涉及积极参与度量活动。第三个工作包将使用新开发的工具来分析在SouthTRAC期间获得的数据，并获得观测到的gw及其源过程的物理洞察力。

Gravity waves (GWs) are an essential driver of global circulation patterns in the stratosphere and mesosphere. Frequently discussed are GWs excited by jets and fronts or GWs excited by flow over orography. In idealized model studies it is easy to separate the two different sources, but for observed waves this is more difficult.We propose to observe GWs with the Gimballed Limb Observer for Radiance Imaging of the Atmosphere (GLORIA) during the SouthTRAC campaign, perform retrievals confined by GW physics with a simple spectral GW model, separate different wave packets by different phase speeds and investigate the origin of these waves via ray-tracing methods.In detail, this will involve the following steps:In order to study GWs in the upper troposphere and lower stratosphere, we perform GW targeted research flights with GLORIA deployed in the belly pod of HALO. We derive 3-D distributions of atmospheric temperatures and trace species from the measured radiances by means of inverse modeling.Due to the time needed to acquire tomographic measurements, at the moment this requires the temperature field to be nearly stationary.To overcome this limitation and investigate non-stationary GWs, we will extend the inversion by including a spectral GW model in the forward model. The aim is a direct gravity wave parameter retrieval.By using the built-in gravity wave model to simulate the vertical propagation of the assumed waves, we achieve a drastic reduction of the state vector and thus a more stable retrieval. This reduction will allow us to include also non-zero ground-based frequencies in the state vector.From the results, 3D temperature fields can be reconstructed for different synoptic time steps.The spectral representation of the GWs inferred in the retrieval can be utilized to separate different phase speeds associated with different sources. The technique can be applied to superpose different waves in the same altitude and time-domain or in the same region. In the upcoming SouthTRAC campaign multi-instrument measurements of complex atmospheric situations will be acquired to observe GWs from different sources over a wide altitude range. This offers the opportunity to examine, how well these waves can be separated and, ideally, if and how these GWs interact.The PhD project consists of three major work packages to achieve this goal.First, the tomographic inversion method needs to be fully developed in cooperation with the mathematics department of the RWTH Aachen. Its capabilities and limitations will be thoroughly investigated using synthetic and model data. The second work package deals with taking active part in the measurement campaign.The third work package will use the newly developed tools to analyze the data acquired during SouthTRAC and gain physical insight into the observed GWs and their source processes.