Download Global-scale modelling of atmosphere

Global-scale modelling of atmosphere-biosphere exchange and interactions between
air quality and climate change
This is a fully funded PhD studentship, with funds from the EU, via CEH.
Supervisors:
David Stevenson ([email protected]) & Richard Essery (University of Edinburgh)
David Fowler & Eiko Nemitz (Centre for Ecology and Hydrology)
This studentship will contribute towards the EU project PEGASOS (Pan-European GasAeroSOls-climate interaction Study). There are two overall aims of the studentship: (i) to
develop and evaluate the atmosphere-biosphere exchange scheme within the UK ChemistryAerosol model (UKCA); and (ii) to apply UKCA to understand and quantify key interactions
between air quality and climate change.
Atmospheric concentrations of several critical air pollutants (e.g., ozone, ammonia, sulphur
dioxide) are strongly influenced by emission from, and deposition to, the biosphere1. These
surface exchange processes are very sensitive to temperature and relative humidity at the
surface and may be expected to respond to global change, with implications for both air
quality (i.e. human health) and ecosystem services (i.e. crop yields, carbon sinks). In
addition, chemical interactions between different compounds during their deposition process
means that changes in the chemical air pollution climate can significantly modify the
atmospheric lifetime and ecosystem inputs of the various compounds. Through synthesis of
results from field campaigns and network flux monitoring stations, new model
parameterisations are becoming available which will be evaluated in UKCA. This modelling
framework will be used to quantify the influence of future changes in surface exchange within
the context of a range of future scenarios of trace gas emissions and global change.
Many air pollutants also exert important influences on climate2, either directly as greenhouse
gases or aerosols (e.g., ozone, sulphate), or via indirect effects on greenhouse gases and
aerosol precursors (e.g., NOx, which via changes in oxidising capacity affects methane and
ozone, and also produces nitrate aerosol). It is important to understand how policies aimed at
controlling air quality also influence climate forcing, as there is the potential for win-win
situations, but also important trade-offs, where some air quality control measures may have
negative impacts on climate. Complex global models, such as UKCA, can used to assess the
multiple effects of individual pollutant controls. Results from these models can then be used
to provide metrics that are more appropriate for use in providing advice to policymakers in
which the full implications of potential control measures are presented. The student will
develop and assess a range of different metrics.
Training will be provided in global Earth system modelling and analysis of large and complex
datasets. He/she will be strongly encouraged to present results at national and international
meetings and will be expected to publish their results in the literature. Applicants should have
a background in quantitative science and some experience of computer modelling. The
student will be based partly at the School of GeoSciences and partly at CEH Edinburgh.
He/she will benefit from being part of lively research and postgraduate student communities
at both organisations and will have the opportunity to interact with scientists in adjacent fields
and within the wider European PEGASOS Consortium, which includes 26 diverse
organisations from across Europe.
References
1. Fowler, D, et al. (2009) Atmospheric composition change: Ecosystems-Atmosphere
interactions, Atmos. Environ., 43, 5193-5267, doi:10.1016/j.atmosenv.2009.07.068
2. Isaksen, ISA, et al. (2009) Atmospheric composition change: Climate-Chemistry
interactions, Atmos. Environ., 43, 5138-5192, doi:10.1016/j.atmosenv.2009.08.003