Upper tropospheric humidity and climate change

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The tiny quantities of water vapour in the air many kilometres above our heads is of central importance to theEarth's greenhouse effect and ongoing climate change. It regulates the planet's natural cooling system throughabsorption of outgoing infrared radiation and where the humidity exceeds saturation point determines thedistribution and thickness of high altitude clouds. Upper tropospheric humidity is an essential climate variablebecause it controls key atmospheric processes, including water vapour and cloud feedbacks that can amplify theclimate system's response to increases in other greenhouse gases such as carbon dioxide. It is therefore vital tounderstand past variability and change in upper tropospheric humidity and evaluate these key processes incomplex climate prediction models.This project will exploit state of the art global satellite measurements and novel diagnostic tools to evaluatedataset quality, quantify the variability of atmospheric humidity in space and time and use this information toadvance understanding of important atmospheric processes as well interrogate and improve detailed weather andclimate prediction models that are of great benefit to society. The research will provide a valuable interfacebetween Earth Observation and climate modelling, as well elucidating feedbacks processes fundamental toclimate change and therefore of great relevance to policymakers. The supervision team provides a broadexpertise across climate science and Earth Observation and there will be the opportunity to work with scientistsfrom the UK Met Office involved in the development of weather and climate models and with scientistsstationed in EUMETSAT who are directly involved in producing and extending key satellite observing systems.The project will tackle some important questions including:- How much does upper tropospheric humidity amplify climate change?- Can state of the art climate models capture the processes determining variability and change in uppertropospheric humidity?- Will signatures from upper tropospheric humidity provide new insight into high altitude cloud feedbacks?- How does upper tropospheric humidity control Earth's radiative energy balance and is there a tropical supergreenhouse effect?The project will exploit existing data, numerical models and diagnostic tools and advance these systems to better interface Earth Observation and climate modelling as well as developing concepts relating to feedbacks processes that are fundamental for policy relevant quantitative climate science as listed below: - Exploitation of new satellite measurements of UTH.- Development of techniques to simulate consistent upper tropospheric humidity diagnostics in current climate models using existing software available from partners- How can upper tropospheric humidity measurements by combined synergistically with Earth radiation budget and water cycle measurementsThere will be opportunities to liaise and learn from EUMETSAT partners involved in developing UpperTropospheric Humidity datasets, the ESA Water Vapour Climate Change Initiative and the Met Office partnerson using and evaluating climate model simulations. This will provide comprehensive training in cross-disciplinary data analysis skills applied to models and Earth observations.