Drivers of change and variability in global atmospheric oxidising capacity

Many air pollutants are mainly removed from the atmosphere through oxidation, e.g. methane and ozone (both important greenhouse gases) and carbon monoxide. Oxidation largely controls the average atmospheric residence times of these gases (about 10 years, 20 days, and 1 month, respectively). The atmospheric oxidising capacity is dominated by the concentration of the highly reactive and consequently very short-lived (seconds) hydroxyl radical (OH). Hydroxyl can be measured, but it is very difficult to do so, and in general we have to infer its global distribution indirectly. We can do this using model simulations of gases that react with OH.

Understanding of the oxidation capacity is required to interpret past levels of methane (and other gases), and to make reliable projections of future concentrations, and hence to assess climate and air quality impacts.

Key research questions
• How has the atmospheric oxidation capacity varied in the past?
• What are the anthropogenic and natural drivers of trends and variability in OH?
• What are the implications for future levels of methane and other greenhouse gases and aerosols?

Methodology
Year 1.
Past changes in oxidising capacity will be assessed, using a combination of model results and observations. The UKESM1 model will be used to investigate the sensitivity of OH to a variety of drivers, both natural and anthropogenic (e.g. variations in stratospheric ozone, El Nino, and emissions of nitrogen oxides).

Year 2.
Models within the CMIP6 archive will be explored to investigate how different models simulate changes in OH, and how these compare to observationally derived trends and variability.

Year 3.
Future projections of oxidising capacity will be explored to see how different model representations affect future levels of methane, ozone, and aerosols.

Training
A comprehensive training programme will be provided comprising both specialist scientific training and generic transferable and professional skills.

Eligibility and qualifications
Only UK/EU citizens resident in the UK for at least 3 years prior to the start of the studentship. Further details and stipend are at www.ed.ac.uk/e4-dtp/how-to-apply/funding-and-eligibility.

You should have, or be expecting to achieve a good Honours or Master’s degree, or equivalent, in a quantitative science background (physics, maths, computing, chemistry), with an enthusiasm for atmospheric science. You should be prepared to analyse very large datasets and run complex Earth System Models.

Application procedure
Applications must be made directly to the E4 DTP https://www.ed.ac.uk/e4-dtp/how-to-apply by the deadline of 9 January 2020

Equality & Diversity statement
The School of Chemistry holds a Silver Athena SWAN award in recognition of our commitment to advance gender equality in higher education. The University is a member of the Race Equality Charter and is a Stonewall Scotland Diversity Champion, actively promoting LGBT equality. The University has a range of initiatives to support a family friendly working environment. See our University Initiatives website for further information. University Initiatives website: https://www.ed.ac.uk/equality-diversity/help-advice/family-friendly