Ben Wōden: Understanding cloud chemistry
Ben Wōden's PhD project, spanning chemistry and meteorology, investigates the atmospheric ageing of mixed organic surfactant monolayers at the air-water interface and will help improve climate prediction.
Surfactants are compounds in which one part of the molecule (the head) is attracted to water, and the other part (the tail) is repelled by it; this means that they form very thin films (monolayers) on the surface of droplets of water, with heads in the water and tails in the air.
Climate and weather models do not accurately represent small-scale processes such as cloud droplet nucleation and growth (there isn't enough computing power in the world for that). Instead, small-scale models of cloud growth and behaviour that explicitly represent molecular-level processes are used to create generalised large-scale rules for the behaviour of cloud cover in various conditions, and these are then used in the larger-scale models.
Ben's research investigates the ageing and activity of nanoscale thin films formed on the surface of cloud droplets by surfactant emissions from a variety of natural and human sources. These thin films alter the properties of clouds in ways that are currently only partially understood and generally poorly represented in climate models. These films vary enormously in their lifetimes in the atmosphere, and, by studying the way they react with key atmospheric oxidants such as ozone in a variety of conditions, Ben hopes to improve understanding of the scale and nature of their likely impacts upon cloud formation and properties.
“My key finding so far is that many of the more reactive films, which might be assumed to have an impact only over a short timescale because they oxidise quickly in the atmosphere, actually produce stable films as products of these oxidation reactions in certain conditions. This means that they could affect cloud properties over a longer period of time than would be predicted if only the effects of the film formed by the initial surfactant film were considered.”
Ben's research will help make our understanding of the small-scale system better, which should allow better approximations to the small-scale system to be incorporated into the large-scale models.
Leading the way in atmospheric research
When looking for a university for his PhD research, Ben recognised the value in joining the University of Reading both on a personal and professional level.
“I selected Reading because of an interest in the specific research project available here, a desire to work with my specific academic supervisor and a liking for both the campus and the town. I was also attracted by the reputation of the atmospheric research carried out in the world-class Department of Meteorology, which my project was associated with.”
Access to some of the best research facilities in the UK
Through the collaboration with the Science and Technology Facilities Council (STFC), Ben had the opportunity to make use of the leading specialist research facilities at the Rutherford Appleton Laboratory (RAL) at Harwell.
“My main work at RAL involved using the INTER neutron reflectometer at the ISIS Pulsed Neutron and Muon Source, onto which I deployed an FT-IR spectrometer incorporated into a reflection-absorption geometry analysis and reaction chamber setup that was designed and built in collaboration with ISIS. I've also worked with a Brewster angle microscope at Diamond Light Source (the UK's national synchrotron).”
As Ben's research is cross-disciplinary, he has benefitted from support from both the Chemistry and Meteorology Departments.
“I enjoy being associated with the Department of Meteorology and the Walker Institute. I value the depth and variety of training and cross-disciplinary opportunities afforded to me by my Doctoral Training Partnership.”
Ben offers the following advice to new PhD students.
“Do as much skills training, networking and interdisciplinary work as you can. You'll never have a better opportunity. Don't stop doing all the things you enjoy, and don't worry if, after six months, you have no useable data.”
When Ben completes his PhD he would like to work in a role which influences how scientific research is made into government policy in the UK.
Ben's PhD was funded by the NERC Science of the Environment: Natural and Anthropogenic Processes, Impacts and Opportunities (SCENARIO) Doctoral Training Partnership and the Science and Technology Facilities Council.