Defra currently use a range of air quality models. Models are used for regulatory compliance modelling against the EU Air Quality Directive and also for scenario modelling, such as assessing the impacts of emission changes or climate change, to develop and evaluate air quality policies and to support statutory reporting for compliance with EU Air Quality Directives and other international commitments. The models differ in the way they combine the complex interaction between atmospheric emissions, transport, chemical conversions and deposition processes.
The Community Multiscale Air Quality model (CMAQ) is a model developed by the USEPA. It is a community open-source model, freely available, well supported and as such evolves to incorporate advances in science. CMAQ is referred to as a ‘one-atmosphere’ model, it is able to produce outputs for a range of pollutants and processes simultaneously. It is currently used by Defra to produce air quality forecasts, but has not, to date, been used for Defra compliance modelling and assessment purposes or for the modelling of future scenarios. Defra would benefit from the use of a single modelling framework, one that can address a range of pollutants and air pollution concerns, optimised and properly evaluated for producing appropriate outputs for UK compliance reporting. The model would need to be able to run scenarios, for example the impacts on air pollutant concentrations to changes in emissions and to produce evidence in a timely and efficient manner.
This project will investigate the benefits of using CMAQ by carrying out a detailed demonstration and evaluation of how CMAQ could meet Defra’s evidence and policy needs. It aims to develop a configuration of the model that is optimised for modelling current and future concentrations of multiple pollutants for different emission scenarios of interest to Defra policy makers. The work programme aims to achieve these objectives in two phases.
The work programme will be carried out by a consortium of the UK’s leading practitioners in the use of CMAQ: Ricardo-AEA, King’s College London and the University of Hertfordshire. The consortium approach will ensure the shared expertise of the partners will be applied to the different tasks in the most cost-effective way to bring the maximum benefits to the overall aims of the project.
The work for Phase 1 in the original contract was divided into four main objectives which were completed in July 2012 and led to a provisional version of CMAQ-UK, a version of CMAQ optimised for Defra applications. Variation 1 enabled further CMAQ runs for Defra model intercomparison Exercise:
Variation 1: CMAQ runs for Defra model intercomparison Exercise Phase 2.
This variation 2 provides a new specification for Phase 2 and includes a task on development of Data Assimilation in UK Air Quality Forecasting:
Variation 2: Phase 2 work programme and Development of Data Assimilation in UK Air Quality Forecasting