HEmispheric and spectral Imaging multi-Camera System (HELICS)

在DFG主要仪器倡议“HALO仪器--高空和远程研究飞机HALO科学仪器的扩展”的框架内，提出了一种名为“HEmispheric和spectraL成像多相机系统（HELICS）”的新型相机系统，并将其安装在HALO大翼吊舱（HLWP）中。目前在HALO上的角分辨辐射仪器包括用有限视场传感器测量太阳和热红外波长范围内向上光谱辐射率的装置。计划利用HELICS测量整个下半球的瞬时二维向上多光谱大气辐射场，从而可以探索大气层和表层的太阳辐射能量收支并改进遥感。HELICS的技术要求来自于通过能够从不同观察方向观察场景的宽视场光谱辐射测量系统来补充当前HALO仪器的需求。这遵循了即将到来的卫星任务的愿景，例如EUMETSAT多视图多通道多偏振成像（3 MI）仪器计划搭载气象业务卫星（MetOp）第二代系列（于2024年初发射）和LIBERA，云和地球辐射能量系统（CERES）的延续，预计将于2026年发射。HELICS将包括一套配备鱼眼广角光学系统的可见光（维斯）和短波红外（SWIR）摄像机，每台摄像机都针对一个波长波段进行调整，以利用摄像机传感器的全空间分辨率（约1兆像素）。整个系统将是自制的，由需要适应特殊环境条件（低环境压力和温度）的市售和定制部件组成。HELICS将提供角分辨光谱辐射率数据，用于各种应用，例如，研究辐射能量收支，改进和验证遥感方法，以按3 MI计划检索云、气溶胶和表面特性，并评估辐射到辐照度的转换，这是量化基于卫星的观测（LIBERA）的地球辐射收支所需的。作为第一次应用，该系统计划成为尚待确定的HALO-（AC）3后续使命的一部分，该使命将研究初步提议于2028年进行的从极夜到极昼过渡阶段的北极云和表面特性。

Within the framework of the DFG Major Instrumentation Initiative „HALO-Instruments – the Expansion of the Scientific Instrumentation of the High Altitude and Long Range Research Aircraft HALO“, a novel camera system entitled "HEmispheric and spectraL Imaging multi-Camera System (HELICS)" is proposed to be developed and installed in the HALO Large Wing Pods (HLWPs). The current angular-resolving radiation instrumentation on HALO comprises devices to measure upward spectral radiance in the solar and thermal-infrared wavelength ranges with sensors that have a limited field of view (FOV). With HELICS it is planned to measure the instantaneous, two-dimensional (2-D) upward multispectral atmospheric radiance field over the entire lower hemisphere, which allows to explore the solar radiative energy budget of atmospheric and surface layers and to improve remote sensing. The technical requirements of HELICS are derived from the demand of complementing the current HALO instrumentation by a wide-FOV spectral radiance measurement system capable of observing a scene from different viewing directions. This follows the vision of upcoming satellite missions such as the EUMETSAT Multi-Viewing Multi-Channel Multi-Polarisation Imaging (3MI) instrument planned to be on board of the Meteorological Operational Satellite (MetOp) Second Generation series (launched in early 2024) and LIBERA, a continuation of the Clouds and the Earth's Radiant Energy System (CERES), with an expected launch in 2026. HELICS will consist of a set of visible (VIS) and short-wave infrared (SWIR) cameras equipped with fisheye wide-angle optics each tailored to one wavelength band to make use of the full spatial resolution of the camera sensors (about 1 MegaPixel). The full system will be self-made, consisting of commercially available and custom-made components that need to be adapted to special environmental conditions (low ambient pressure and temperature). HELICS will provide angular-resolved spectral radiance data that will be used for various applications, e.g., to investigate the radiative energy budget, and to improve and validate remote sensing methods to retrieve cloud, aerosol, and surface properties as planned for 3MI as well as to evaluate the radiance to irradiance conversion that is required to quantify the Earth's radiation budget from satellite-based observations (LIBERA). As a first application, the system is planned to be part of the still to be defined follow-up mission of HALO-(AC)³ that will study Arctic cloud and surface properties during the transition phase from polar night to polar day tentatively proposed for 2028.