HALO 2020 – Cloud effects on solar actinic radiation: Evaluation of satellite-aided radiative transfer model calculations with HALO measurements

在本项目中，将使用六个HALO任务的紫外/可见光谱光化度通量密度测量值来评价基于业务卫星云检索的辐射传输模式计算。HALO任务中的五个已经完成：TECHNO（2010年）、NARVAL-I（2014年）、OMO（2015年）、EMERGE（2017/2018年）和CAFE-Africa（2018年），总共进行了大约75次研究飞行。此外，还将纳入CAFE-Brazil（2020）的数据。光谱光化通量密度测量的主要目的是得出光解频率，这对光化学研究很重要。HALO测量为评估卫星衍生的光解频率提供了难得的机会，因为它们提供了覆盖全球不同高度和任务区域的高分辨率现场样本。此外，在TECHNO、NARVAL和OMO期间，一个任务伙伴还对HALO进行了最低光谱辐射测量。这些测量覆盖了整个太阳光谱范围，并提供了关于飞机下方云层特性的独立的本地信息。这将有助于解释和正确应用卫星数据。本项目处理的主要问题是，考虑到现有的卫星云信息，模拟的辐射传输数据和测量的辐射传输数据是否能够合理一致，以及在不同的任务地区和高度范围内是否获得一致的结果。如果这种方法是成功的，评估的预测，用户定义的3D光解频率场及其误差估计可以基于卫星云信息产生。这些光解频率场可以用来测试化学输运模型的预测，或者它们可以直接作为未来研究中此类模型的输入。在这个项目中打算进行一个相应的案例研究。从这些应用中，未来的HALO任务及其科学分析也可以受益。

In this project UV/VIS spectral actinic flux density measurements of six HALO missions will be used for an evaluation of radiative transfer model calculations based on operational satellite cloud retrievals. Five of the HALO missions have already been completed: TECHNO (2010), NARVAL-I (2014), OMO (2015), EMERGE (2017/2018), and CAFE-Africa (2018) with a total of around 75 research flights. In addition, data of CAFE-Brazil (2020) will be included. The main purpose of the spectral actinic flux density measurements is to derive photolysis frequencies that are important for photochemical research. The HALO measurements provide a rare opportunity for an evaluation of satellite derived photolysis frequencies because they provide high resolution spot samples that cover different altitudes and mission areas globally. Moreover, during TECHNO, NARVAL and OMO also nadir spectral radiance measurements were performed on HALO by a mission partner. These measurements cover the complete solar spectral range and provide independent, local information on cloud properties below the aircraft. That will help to interpret and correctly apply the satellite data. The main question addressed in this project is whether or not radiative transfer modelled and measured data can be brought into reasonable agreement by taking into account available satellite cloud information and if consistent results are obtained for different mission areas and altitude ranges. If this approach is successful, predictions of evaluated, user-defined 3D fields of photolysis frequencies and their error estimates can be produced based on satellite cloud information. These photolysis frequency fields can be used to test chemistry transport model predictions or they can serve directly as an input for such models in future studies. A corresponding case study is intended within this project. From these applications also future HALO missions and their scientific analyses could benefit.