Dr Leighton Regayre

Profile

I hold a joint position, funded by the UK MEt Office (70%) and CEMAC at the University of Leeds (30%), and am responsible for developing aerosol evaluation tools and methods to further our understanding of aerosol in Met Office models. I have broad experience in other institutions, including working as an applied statistician in agriculture science, teaching secondary school mathematics and leading Mathematics education teams. I have participated in and led several large research projects including:

• Aerosol-MFR, 2023 – Present (Co-I)
• The FORCeS project (FORCeS), 2021 – 2023, (Senior research fellow)
• CSSP-China, 2018 - 2021 (Co-I and PI)
• The Aerosol-Cloud Uncertainty REduction project (A-CURE), 2017 - 2021, (Research fellow)
• Securing Multidisciplinary UndeRstanding and Prediction of Hiatus and Surge events (SMURPHS), 2016 - 2017, (Research fellow)
• Copernicus Atmospheric Monitoring Service: Climate Forcings (CAMS 74), 2016 - 2017, (Research fellow)

I'm an active member of our institute. I've been postdoctoral representative, postgraduate student representative and internal seminar organiser. My PhD ‘Quantifying and interpreting the climatic effects of uncertainty in aerosol radiative forcing’ was recognised for ‘Research Excellence’ by the University of Leeds in 2016.

Responsibilities

• Aerosol evaluation
• Organising committee - Analysis of PPEs in Atmospheric Research (APPEAR) seminar series

Research interests

My joint role with the UK Met Office Atmospheric Parameterisations and Processes (APP) team and CEMAC will improve our ability to efficiently evaluate skill at simulating aerosol in Met Office models, across space and time scales. The accurate representation of aerosol in models has wide-reaching implications, from increasing the reliability of climate predictions to improving air quality forecasting and overall predicability of high-impact weather phenomena. Achieving this goal involves:

• Developing an aerosol evaluation toolkit (preliminarily based on the GASSP observational dataset)
• Processing observational data sets to make them ‘model ready’
• Contributing to aerosol community (AeroCom) mulit-model experiments
• Identifying model structural errors using perturbed parameter ensembles (ideas explored in the APPEAR seminar series)
• Evaluating the impact of structural model changes on aerosol

My research goals align with those of the NERC Pushing the Frontiers project, Aerosol-MFR (Maximum Feasible Reduction). In Aerosol-MFR, led by Prof Ken Carslaw and co-led by Dr Jill Johnson and myself, we are developing novel statistical and machine-learning methods to maximally constrain aerosol forcing uncertainty. Within the NERC-funded ACURE project, we tackled the aerosol forcing uncertainty through a comprehensive synthesis of aerosol, cloud and atmospheric radiation measurements, combined with innovative ways to analyse global model uncertainty. We produced a large set of model variants (a perturbed parameter ensemble, or PPE) that spans the uncertainty in multiple model parameters. Advanced statistical methods were used to generate essentially millions of model simulations that enable the full uncertainty of the model to be explored. The spread of these simulations were then be narrowed by comparing the simulated aerosols, clouds and aerosol-cloud relationships against extensive measurements. Yet, substantial uncertainty remained. In our recent contributiuon to the EU FORCeS project, we developed methods to identify structural model errors using our PPEs and thus constrained aerosol effective radiative forcing uncertainty meaningfully for the first time. Aerosol-MFR, and my role as aerosol evaluation scientist, will further develop these methods and allow us to maximally constrain aerosol forcing uncertainty within the feasible limits imposed by the current version of the UK Earth System Model.

My PhD (2012-2016) research identified the causes of uncertainty in the aerosol-cloud interaction component of the aerosol effective radiative forcing over multiple forcing periods and multiple regions of climatic importance. In my thesis I presented an analsis of the causes of model uncertainty in aerosol radiative forcing and for the first time aerosol effective radiative forcing (including rapid atmospheric adjustments). This analysis revealed the important regional, seasonal and anthropogenic emission period differences in the main causes of uncertainty. I analysed the causes of uncertainty in climatically important regions where aerosols are understood to affect dynamical systems on the decadal scale. My research has highlighted the importance of both aerosol and physical atmosphere parameters as causes of uncertainty in aerosol effective radiative forcing. I've also shown that satellite measurements of top-of-the-atmosphere radiative fluxes do provide some constraint on aerosol forcing uncertainty. But, I've also shown that the constraint is limited because accounting for multiple causes of uncertainty means there are many observationally-plausible ways of getting the same result. I'm interested in finding combinations of measurements that provide a strong constraint on aerosol forcing uncertainty. Reducing this important source of model uncertainty will greatly improve model skill at making climate projections.

• CHN19/3: Aerosol effects on Chinese regional climate dynamics; RG.EVEA.119934

Qualifications

• PhD, Research Excellence, Aerosol radiative forcing uncertainty, University of Leeds
• MSc, Atmosphere and Ocean Dynamics, University of Leeds
• BSc (Hons in Statistics), University of Queensland
• QTS, Qualified Teacher Status, Bradford College
• ULTA-1, University of Leeds Teaching Award - Level 1 (Merit), University of Leeds

Professional memberships

• Associate Fellow of the Higher Education Academy
• American Geophysical Union
• Priestley Centre for Climate Futures

Student education

I have over a decade of teaching and leadership experience in secondary Mathematics education. At the University of Leeds I have tutored multiple Applied Mathematics and Statistics courses within the School of Earth and Environment and the School of Mathematics. In 2015 I was awarded the University of Leeds Teaching Award (ULTA-1) and developed my ability to deliver highly-accessible learning opportunities for students. In 2020-2021 I lectured on the level 2 modules ‘Data Analysis and Visualisation’ and ‘Climate Change: Science and Impacts’. I currently supervise multiple PhD and Masters students.

Research groups and institutes

• Institute for Climate and Atmospheric Science
• Atmospheric Chemistry and Aerosols

Current postgraduate researchers

• Léa Prévost