Observing the two- and three- dimensional distributions of trace gases with the Heidelberger Airborne Imaging DOAS Instrument (HAIDI) on board HALO during the phase II mission EMerGe

该项目的重点是应用新的遥感2D和3D成像DOAS仪器Haidi来调查欧洲和亚洲主要城市污染中心(特大城市)排放的羽流的化学成分。这些活动将是德国研究飞机光环的Emerge任务的一部分，目前正在调查CAFE任务的另一部分。通过海迪的航空观测，可以测量表征这些MPC外流羽流的关键参数，包括NO2、HCHO、SO2、CHCHO、BRO、IO、OClO、H2O、O4和O3的痕量气体分布以及气溶胶光学性质。得到的2D地图分辨率优于100m，宽度约10公里，因此一次覆盖大片区域。使用层析成像技术，可以检索包括关于垂直分布的信息的3D地图。海迪观测了一些最相关的气体，以研究流出的MPC羽流的化学成分和转化。我们将研究这些羽流的大小、分布和空间变化与地形和气象的关系。特别是对作为关键成分的NO2的排放、转化和损失进行了研究。结合在光晕上进一步观测到的组分，微量气体和气溶胶成分的化学变化是回答MPC排放羽流对当地、区域和全球影响的主要兴趣。HAIDI还可以得到气溶胶光学性质，这将与对Halo上气溶胶特征的现场测量结合使用，以量化这些MPC羽流对大气辐射收支的影响。此外，导出的痕量气体分布是在Emerge项目内验证和改进模型数据的关键数量。预计将对卫星数据进行进一步验证。有了海迪，一个具有3D能力的系统将首次部署，该系统允许获得完整的3D痕量气体(和气溶胶光学性质)分布。为此，海迪使用了三台指向不同方向的成像DOA仪器。在这个项目中，我们将在以前工作的基础上开发算法，将这些数据集在辐射传输模型中与层析方法相结合。由于这是海迪首次在Halo上运营，因此它必须在这个项目内经历认证和适配过程。

The focus of this project is on the application of a new remote sensing 2D and 3D imaging DOAS instrument HAIDI to investigate the chemical composition of plumes emitted from major urban pollution centers (MPC) (megacities) in Europe and Asia. The activities will be part of the EMerGe mission for the German research airplane HALO, with an additional participation in the CAFE mission being currently under investigation. Airborne observations by HAIDI allow for measurements of key parameters for the characterization of these MPC outflow plumes, including trace gas distributions of NO2, HCHO, SO2, CHOCHO, BrO, IO, OClO, H2O, O4 and O3 as well as aerosol optical properties. The resulting 2D maps have a resolution better than 100 m with a width of ~10 km and thus cover large areas at once. Using tomographic techniques, 3D maps including information on the vertical distribution can be retrieved. HAIDI observes some of the most relevant gases to study the chemical composition and transformation of the MPC plumes in the outflow. We will study the size, distribution and spatial change of these plumes in dependence of topography and meteorology. Especially emission, transformation, and loss of NO2 as a key component will be investigated. In combination with further observed components on HALO, the chemical change of the trace gases and aerosol composition is of main interest to answer questions of the local, regional, and global influence of MPC emission plumes. HAIDI can also derive aerosol optical properties, which will be used in combination with in-situ measurements of aerosol characteristics on HALO to quantify the effect of these MPC plumes on the atmospheric radiation budget. Furthermore, the derived trace gas distributions are key quantities for the validation and improvement of model data within the EMerGe project. A further validation of satellite data is envisaged. With HAIDI, a system with 3D capability, allowing to derive full 3D trace gas (and aerosol optical property) distributions, will be deployed for the first time. For this purpose, HAIDI uses three imaging DOAS instruments pointing at different directions. In this project we will - based on our previous work - develop algorithms to combine these dataset in a radiative transfer model with tomographic approaches. Since this is the first time HAIDI operates on HALO, it has to undergo the certification and adaptation process within this project.