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

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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.