CR2025_29 Remote Sensing of Solar Induced Fluorescence in Forests

Lead Supervisor: Tristan Quaife, Department of Meteorology, University of Reading and National Centre for Earth Observation

Email: t.l.quaife@reading.ac.uk

Co-supervisors: Peter North, Department of Geography, Swansea University; Michael Bell, Forest Research.

Observations of Solar Induced Fluorescence (SIF) are the first direct measurement of the process of photosynthesis that can be made from remote instruments, including satellites and aircraft. Consequently, because photosynthesis is an integral part of the global carbon cycle and hence the Earth’s climate system, SIF observations have the potential to revolutionise our understanding of how the biosphere interacts with climate change.  Although the processes that lead to fluorescence by chlorophyll are well understood in-vitro, there is still much uncertainty in how we can quantify photosynthetic uptake of carbon using satellite based observations of SIF. One important confounding factor is the sensitivity of the SIF signal to the 3D structure of vegetation canopies, which has direct control over the probability that a fluoresced photon will exit the canopy and be viewed by a satellite. This PhD project will examine the link between 3D vegetation structure, photosynthesis and SIF.

The student will have access to a large amount of relevant data collected at the Alice Holt forest in Hampshire, which is run by Forest Research. These data include aircraft and drone measurements of SIF as well as large amount of data on forest structure and carbon fluxes. There will also be opportunities for the student to spend time at Alice Holt and conduct their own field campaigns to support the PhD. The data will be used to parameterise and validate the FLIGHT model, which is capable of predicting both photosynthesis and SIF from forest stands, treating each tree independently. A key objective of this PhD project is to enhance our understanding of the linkages between the 3D vegetation structure, fluorescence and photosynthesis; something the FLIGHT model is uniquely positioned to do. FLIGHT has a long heritage of being used to tackle problems of this nature, and the student will be supported in this by one of the project supervisors who is the originator of the model. However, within this topic there is significant scope for the student to approach the underlying scientific problems according to their individual strengths, from taking a more data driven approach, to theoretical developments in the context of the model.

Ultimately, this project will provide important information required to accurately monitor and model the global carbon cycle. Beyond the PhD project itself, there is significant potential for the student’s work to feed through into other activities, such as evaluation of the UK’s flagship climate model (UKESM), the monitoring of climate change impacts such as drought, and the development of new SIF retrieval algorithms by national space agencies.

The project will be run as part of the UK National Centre for Earth Observation (NCEO), and the student will be part of the NCEO community. They will be able to attend the annual NCEO science meetings and early-career researcher conferences, as well as take advantage of various training opportunities within the centre. NCEO is the UK’s leading research centre for using satellite data for environmental monitoring and has a strong background in the production and exploitation of SIF data. The PhD student will be able to take advice from a range of experts within the centre.

There is currently significant interest in the use of space borne measurements of SIF, and there are several new satellite missions planned, including the European Space Agency’s FLEX satellite, the world’s first dedicated SIF mission. Upon graduating, the student on this PhD project will be well positioned to become a researcher in this field with potential to secure jobs working directly with such satellite missions.

Training opportunities: 

The student will spend at least three months with Forest Research receiving training in how to take relevant measurements, conducting a field campaign and processing collected data. We can be flexible with this component of the PhD and it could be undertaken as a single block, or in smaller chunks. The site is about a one hour drive from Reading. The student will be registered with NCEO and have the option to attend scientific meetings, including the annual student meeting. The lead supervisor’s group meets every week to discuss research and build connections across projects. 

Student profile: 

This project would be suitable for students with a degree in physics or computer science, with an interest in applying their skills to environmental problems, or students with degrees in geography or biology who have good quantitative skills. Some level of computer programming will be required, and experience of fieldwork is a bonus. 

Co-Sponsorship details: 

This project will receive a CASE award from Forest Research.