The Universal InfraRed Airborne Spectrometer: A new instrument for climate research

驱动气候变化的因素是什么？我们如何限制对未来气候系统如何演变的预测？研究地球的辐射收支，特别是它发出的长波能谱，为回答这些问题提供了一条有希望的途径。理论模型表明，全球范围内，地球发射回太空的辐射中有一半的波长大于15微米。这一光谱区域被称为远红外，受到水蒸气、云以及高纬度地区地表特性的强烈影响：所有这些都与关键的气候反馈有关。然而，地球的远红外光谱从未被测量过。随着欧洲航天局第九次地球探测任务FORUM（远红外辐射理解和监测）（https://www.forum-ee9.eu/）的发射，这种情况将在未来几年有所改变。为了准备任务并了解它将提供什么，帝国理工学院与ABB加拿大公司合作，正在建造一个机载演示器，即通用红外机载光谱仪（UNIRAS）。UNIRAS覆盖6.25-100微米的光谱范围，将是世界上唯一能够测量远红外和中红外的机载仪器。仪器设计的核心是最先进的傅立叶变换光谱仪（FTS）。ABB负责交付FTS，而Imperial将设计和构建前端校准系统，并将这两个组件集成在一起。为了对仪器的性能有信心，必须首先在地面上，然后在飞行中对其进行精确校准和彻底测试。利用RAL空间和帝国的专业知识，这个项目的主要目标是协助UNIRAS的集成和校准验证。这将包括对实验室和飞行性能的详细分析，描述仪器行为的各个方面。该项目的时间安排是这样的，在2025年初，还应该有机会参加英国气象局计划的飞行活动。该活动的目的是利用远程和原位传感器的结合，更好地限制卷云在电磁波谱上的辐射效应。因此，第二个项目目标将是利用unira在运动期间所做的观测来测试当前的卷云参数化。这可能涉及使用RAL空间目前正在开发的一种新的检索代码。这个项目代表了一个难得的机会，可以为直接有利于太空任务的硬件开发做出贡献。它适合具有物理科学或工程经验的候选人，他们希望进行动手实验工作，并结合数据分析。有机会前往欧洲空间局的ESTEC，并与美国的地球观测小组进行旅行和合作。

What drives climate change and how can we constrain predictions of how the climate system will evolve in the future? Studying the Earth's Radiation Budget and, in particular, its outgoing longwave energy spectrum, offers a promising route to answering these questions.Theoretical models suggest that globally half the radiation emitted by Earth back to space is at wavelengths greater than 15micrometer. This spectral region is referred to as the far infrared and is strongly influenced by water vapour, cloud and, at high latitudes, surface properties: all of which are linked to key climate feedbacks.However, the Earth's outgoing spectrum in the far infrared has never been measured. Thisis set to change in the coming years with the launch of the European Space Agency's 9th Earth Explorer mission, FORUM (Far-infrared Outgoing Radiation Understanding and Monitoring) (https://www.forum-ee9.eu/). To prepare for the mission and gain an understanding of what it will deliver, Imperial College, in partnership with ABB Canada, arebuilding an airborne demonstrator, the Universal InfraRed Airborne Spectrometer (UNIRAS). Covering the spectral range 6.25-100 micrometres, UNIRAS will be the only aircraft-based instrument in the world capable of measuring across both the far and mid infrared. At the heart of the instrument design is a state-of-the-art Fourier transform spectrometer (FTS). While ABB has responsibility for delivering the FTS, Imperial will design and build the front-end calibration system and integrate the two components. In order to have confidence in the instrument performance it must be accurately calibratedand thoroughly tested, first on ground, then, in-flight. Exploiting expertise at RAL Space and Imperial, the main goal of this project is to assist with the integration and calibration-validation of UNIRAS. This will involve detailed analysis of laboratory and in-flight performance, characterising every aspect of the instrumental behaviour.The timing of the project is such that there should also be the opportunity to participate in a planned Met Office flight campaign during early 2025. The campaign has the aim of better constraining the radiative effect of cirrus cloud across the electromagnetic spectrum, using a combination of remote and in-situ sensors. A secondary project goal will thus be to exploit UNIRAS observations made during the campaign to test current cirrus parameterisations.This could involve the use of a new retrieval code currently under development at RAL Space.This project represents a rare opportunity to contribute to the development of hardware that will directly benefit a space mission. It would suit a candidate with experience in either the physical sciences or engineering, who has a desire to perform hands-on experimental work, coupled with data analysis. There is scope for travel to the European Space Agency at ESTEC, and for travel and collaboration with an Earth Observation group in the USA.