Modelling of weather and air quality
Charles Chemel, Rong-Ming Hu, Elizabeth Somervell, Ranjeet S Sokhi, Ye Yu (Chinese Academy of Sciences), Bernard Fisher (UK Environment Agency), Jaakko Kukkonen (FMI) and Douglas R Middleton (UK Met Office)Our group is using state-of-the-art modelling tools for addressing key issues in meteorology and air quality research. A special emphasis is being placed on the dynamical, physical and chemical processes that affect air quality on scales ranging from global down to turbulence scales. Our interests cover areas of frontier research across these scales. Our current research fits within the MESOMAQ activity under NCAS/Weather. Presently, the work is funded by NERC, the UK Environment Agency, and the European Commission. Click on the individual links below to find out more about our recent and current work.
Global scales
Global models can provide the large-scale atmospheric dynamics and the distribution of atmospheric trace gases and aerosols throughout the Earth’s atmosphere at a typical resolution of 1°, corresponding roughly to 100 km. These models are generally used to simulate large-scale features that influence regional patterns.
Regional scales
Global models can provide the large-scale picture of atmospheric dynamics and chemistry but their representation of features occurring on smaller temporal and spatial scales is poor due to their coarse horizontal resolutions. Indeed, spatial features smaller than a grid box are averaged out. For that reason, limited-area or mesoscale models are being used for investigations at resolutions of up to 1km.
- Regional air quality and impacts of large point sources
- Atmospheric Chemistry and Regional Ozone in Industrial Plumes
- Comparison of simple and advanced regional models
- Impacts of urban areas on regional air quality
- Cross-tropopause transport induced by deep tropical convection
Local/urban scales
The local scale refers to spatial scales of about hundred metres up to about few kilometres. Urban scales usually refer to spatial scales of about few kilometres to several tens of kilometres. At these scales finer resolution models are employed and some features that are traditionally considered ‘subgrid’ in mesoscale models, and thus needs to be parametrized, become explicit. Convection is a good example. In addition, the assessment of the airflow is more challenging as details of the terrain such orographic or urban features becomes even more important.
- Urbanisation of the UK Met Office Unified Model
- Effects of landuse heterogeneities on air quality over London
- Modelling urban meteorology with MM5
- Effects of orography on air quality in deep and narrow valleys
- Integrated modelling system for air quality assessment
Turbulence scales
The parametrization of turbulent mixing processes is crucial for the transport, mixing and dry deposition of pollutants within the atmospheric boundary layer. In all boundary-layer flow parameterisations, the scale of the turbulent structures is assumed to be much smaller than the grid spacing. This assumption is reasonable for grid spacings of the order of a couple of kilometres or more but cannot be used for grid resolution of one kilometre or less. Important research issues are thus raised regarding this interface between explicit representation and parametrization.
- Entrainment and mixing processes in stably stratified layers
- Initiation of convective processes and associated transport
Bridging the scales
Progress on scale and process interactions has been limited because of the tendency to focus mainly on issues arising at specific scales. However the inter-relating factors between the sources of air pollution and their impacts on the environment rely on atmospheric processes and interactions operating on a whole range of scales. Therefore, a consistent, integrated framework bringing together the treatment of meteorology, emissions and chemistry is required.