EMEP4UK: Application of the EMEP unified model to the UK

Project background

This project is funded by Defra (Department for Environment, Food and Rural Affairs) (Defra - AQ0702), with additional financial support from CEH and the Norwegian Meteorological Institute (met.no). Based on previous work, EMEP4UK development has reached the stage at which the model is operational. It is coordinated by CEH and model development carried out by CEH in conjunction with the University of Edinburgh (UoE).

Currently, the FRAME model is used by Defra to simulate the spatial patterns and future scenarios of transboundary pollutant concentrations and deposition of acidifying and eutrophying pollutants.

FRAME is very well suited to policy needs, with a fast simulation time allowing multiple scenarios to be calculated including point source and county-level analysis for the UK Integrated Assessment Model (UKIAM).

By contrast to the present benefits of FRAME, it is recognized that during the course of this project, state-of-the-art Eulerian modelling is expected to be able to replace Lagrangian modelling of air pollutant fluxes at the UK scale. This has the advantage of using detailed temporal meteorology calculated with the Weather Research Forecast (WRF) model rather than statistical meteorology (with FRAME) which is therefore better able to represent atmospheric chemical processes, and provide a more reliable simulation of source-receptor relationships.

It must be recognized, however, that such Eulerian models are computationally more intensive, and is not yet feasible to run multiple-source receptor matrices from a Eulerian model for the UK at a fine resolution. EMEP4UK simulates a number of different atmospheric pollutants including nitrogen and sulphur deposition, surface ozone and particulate matter.

In order to provide the basis for an eventual migration to Eulerian modelling for UK policy analysis, the underlying model developments need to be made in parallel with the continuous improvement in computational facilities. The project CPEA 27 has provided the first step toward the eventual long term goal, by successfully establishing a nested UK version of the EMEP model (EMEP4UK) running at a 50 km resolution over Europe and at a 5 km resolution over the UK.

EMEP4UK aims and objectives

The specific long-term aims for EMEP4UK are:

  • To provide an advanced modelling tool that can support UK transboundary air pollution policy evaluation, incorporating the effects of actual meteorology and allowing analysis of future scenarios for different years.
  • To provide a platform for the ongoing exchange of knowledge between the UK and the EMEP programme, facilitating improved understanding of the EMEP model as used in calculations for the CLRTAP (Convention on Long-Range Transboundary Air Pollution).
  • To provide a vehicle by which the effects of new UK scientific findings can be considered within a sub-domain of the EMEP model, with consideration for eventual application in the full EMEP model used in the CLRTAP.

Overall, the result of the project is to provide a more robust scientific underpinning for making future decisions regarding air pollutant abatement strategies. The EMEP4UK model is already sufficiently well developed for the purposes of addressing policy-related questions that do not require long-term simulations.

The focus of the next phase of the work should be to provide the basis for long-term simulations covering a full year of meteorological and chemical simulation. This facility will be applied to allow assessment of air pollution issues (i.e. deposition of nitrogen and sulphur, particulate concentrations and ozone concentrations) for future years based upon emissions scenarios such as those for the Air Quality Strategy and the National Emissions Ceiling Directive for 2010 and 2020.

EMEP4UK-related PhD studentships

  • Diletta Cordeschi (High resolution modelling of precipitation and sulphur and nitrogen disposition) with the School of Geosciences, UoE.
  • Monica Agostinone (Numerical simulation of air quality in the UK) with the School of Chemistry, UoE.

Selected results

EMEP4UK simulated daily max surface ozone for the first two weeks of August 2003 (ppb)

EMEP4UK simulated daily max surface zone for first two weeks in August 2003
(ppb), Vieno et al, 2009

Observation vs. simulated surface ozone for hourly, daily and monthly (Aston Hill)

Observations vs. simulated surface ocean - hourly, daily and monthly (Aston Hill)

Example of EMEP4UK simulated hourly ozone vs AURN observations (Aston Hill)

Example of EMEP4UK simulated hourly ozone vs. AURN observations (Aston Hill)