Current research interests
Radiative forcing
I am involved in the Radiative Forcing Model Intercomparison Project (RFMIP) and will be diagnosing the effective radiative forcing from climate models participating in CMIP6. The effective radiative forcing (ERF) describes the top-of-atmosphere energy budget change for a change in input to the climate system, for example an increase in CO2. It is very closely related to the eventual change in global mean surface temperature.
Rapid adjustments are a key component of the ERF and contribute singificantly to its current uncertainty. I focus on rapid adjustments for a class of idealised forcing experiments.
I have produced radiative kernels for TOA and surface from the HadGEM2 climate model. These can be obtained here.
Climate modelling
I run the UK Met Office's HadGEM2 and HadGEM3 climate models for a number of different science questions. In the SMURPHS project I am looking at the ERF response to a time series of historical forcing inputs to determine whether there are clear relationships between historical ERF changes and surface temperature response and whether this explains phenomena such as the observed slowdown in global temperature rise seen between 1998 and 2012. I am also using climate models to determine possible feasible pathways to a 1.5°C future.
I developed the non-CO2 forcing components of the FaIR simple climate model and am seeking to actively develop this model further.
Previous and ongoing research interests
Solar energy
Current and future solar resource assessment using radiative transfer techniques: Climate change is likely to change global temperatures and solar irradiance levels, but this will be distributed unequally across the world. Some areas could experience large improvements or declines to their solar energy potential in the future compared to the present. In addition, radiative transfer models can calculate the spectral irradiance distribution from a given atmospheric state, and can be used to predict solar resource in both current and future climates by applying the surface irradiance spectrum to the spectral response of a PV cell. The future climate scenario is extended by considering geoengineering with stratospheric sulphate injection.
Statistics of cloud transmission: Using a radiative transfer computation to generate a clear sky climatology for the UK incorporating aerosols from GLOMAP and water vapour and ozone from ECMWF, the ratio of actual irradiance to theoretical clear-sky irradiance can be represented by a non-dimensional value, the "clear-sky index", which describes the attenuation due to clouds alone. The Met Office Integrated Data System (MIDAS) provides hourly records of irradiance and cloud fraction for 63 sites in the UK. The statistics derived were used in a stochastic weather generator model by Jamie Bright.
Passive cooling of solar cells using phase change materials (PCMs): Crystalline silicon photovoltaics, which are by far the most common at present due to their low cost and high manufacturing capacity, decline in performance as their operating temperature increases. High irradiance levels, which makes PV attractive in many regions, causes cell operating temperatures to increase. PCMs coupled to solar modules are one way to passively keep cell temperatures nearer to the ambient by delaying and/or limiting cell temperature rise during peak solar hours. PCMs are substances that change from solid to liquid with a large latent heat capacity, which is used to absorb the excess heat energy from the solar module. Passive cooling requires no moving parts, unlike water cooling, and such the maintenance burden is minimised. My research has implemented modelling and experimental studies on integrated solar modules with PCMs.
Other areas
As part of the Low Carbon Technologies DTC program I undertook two mini-projects in my first year in non-solar energy subjects, as follows.
Transport: The effectiveness of the UK vehicle scrappage scheme in reducing fleet-wide CO2 emissions was analysed, when taking into account the embedded carbon in early manufacture of a new car and disposal of an old one. Interestingly, it was found that despite the scrappage scheme not being designed primarily as a CO2 reduction measure, it has been successful in reducing total CO2 emissions from passenger cars in the UK.
Wind energy: The project group was asked to investigate the feasibility of placing a small wind turbine on the roof of the new energy building at the University of Leeds. Part of this study involved modelling the aerodynamics of several small vertical axis wind turbines based on their diameter, blade size, blade number and height. It was concluded that from both economic and carbon payback perspectives that a turbine would not be viable in this location. This is an important result as a poorly performing turbine, if installed, could cause negative publicity for wind energy.