The motivation for my research is to understand the chemical and dynamical factors that determine changes in atmospheric composition. These are fascinating as scientific problems in their own right and are also important for global environmental issues such as stratospheric ozone depletion and climate change. In the past, scientists have concentrated on relatively short term chemical processes (seconds to weeks); it is now important than ever to understand how atmospheric composition is influenced by longer-term processes (weeks to years).
A wealth of measurements exists that has been collected in global monitoring networks, during focussed field campaigns and by satellite instruments. Great opportunities exist to exploit these data to understand a range of atmospheric problems. My approach is to analyse and interpret the available measurements, collaborating closely with the atmospheric modelling (Prof. Pyle) and measurement (Prof. Jones and Dr Kalberer) groups in the Chemistry Department. Given the global nature of the problems considered, international collaborations are important components of the work. Topics are being studied include:
- Stratospheric ozone depletion over northern hemisphere. Quantifying past ozone loss and particularly the relative importance of chemical depletion and dynamical influences is essential to understanding how stratospheric ozone will change in future;
- Emissions of trace gases in South East Asia. Gases emitted from the Tropical oceans (halocacarbons) and forests (isoprene and terpenes) have important impacts on the global atmosphere. We are making measurements of their concentrations and using models to investigate their emissions and impact.
- Transport of chemical species in the Tropics. The bulk of air entering the stratosphere does so in the Tropics. Measurements from aircraft campaigns in the pacific are analysed to quantify the vertical transport in the extremely strong storms in the Pacific.
- Emissions of greenhouse gases in the United Kingdom. We are developing analytical techniques using our own measurements to quantify these emissions at local scales, with the aim of improving avaiable monitoring networks and to pinpoint where emissions are occurring.
In addition to using off the shelf instruments, I have a small group developing and constructing instruments capable of running autonomously in order to make observations for months and years at a time. These custom-built instruments are used to make measurements of short-lived halocarbons and hydrocarbons at sites in Malaysia and other locations in the West Pacific (Taiwan, Australia and New Zealand), where there are few measurements. The observations are valuable in their own right, and are being used to estimate emissions of these compounds, which are important for ozone in the stratosphere and troposphere and possibly for particle formation over the remote oceans.
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