Non-stationary Gravity Wave retrievals for GLORIA

重力波是平流层和中间层全球环流模式的重要驱动力。经常讨论的是由急流和锋面激发的全球Ws或由地形上的气流激发的全球Ws。在理想模式研究中，分离两个不同的源是容易的，但对于观测到的波，这是比较困难的。我们建议在SouthTRAC活动期间使用用于大气辐射成像的万向支架观测器（格洛丽亚）观测GW，使用简单的光谱GW模型进行GW物理约束的反演，通过不同的相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。具体而言，这将涉及以下步骤：为了研究大气层上部对流层和平流层下部的GW，我们在HALO的腹部吊舱中部署格洛丽亚进行GW目标研究飞行。我们通过反演模型从测量的辐射率中得到大气温度和痕量物质的三维分布。由于获得层析测量所需的时间，目前这需要温度场接近平稳。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包括光谱GW模型来扩展反演。我们的目标是直接反演重力波参数，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，从而更稳定的反演。这种简化将允许我们在状态矢量中也包括非零的地基频率。从结果中，可以重建不同天气时间步长的三维温度场。在反演中推断的GW的谱表示可以用来分离与不同源相关的不同相速度。该技术可应用于同一高度、同一时域或同一区域的不同波的叠加。在即将进行的SouthTRAC活动中，将获得复杂大气状况的多仪器测量数据，以观测不同来源在大高度范围内的全球变暖。这提供了机会来检查，如何以及这些波可以被分离，以及，理想情况下，如果以及如何这些GW相互作用。博士项目包括三个主要的工作包，以实现这一目标。首先，层析反演方法需要充分开发与RWTH亚琛的数学系合作。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测量活动，第三个工作包将使用新开发的工具分析SouthTRAC期间获得的数据，并对观测到的全球变暖及其源过程进行物理分析。

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.