Department of Meteorology, University of Reading

High-resolution numerical weather prediction for local-scale air quality prediction over cities

There is compelling evidence of the health impacts of air pollution in cities, which means that accurate local air quality forecasting is now a priority. Such forecasting depends critically on high-resolution numerical weather prediction. The UK Met Office is developing the Unified Model (MetUM) to run at order 1km to 100m resolutions. However, it is unclear how turbulence should be modelled at these resolutions; this is important as it affects dispersion of pollutants in the urban atmosphere. Additionally, as individual buildings will not be resolved, how should they be represented? It is uncertain whether aerodynamic drag should be represented as being vertically distributed (due to the urban “canopy” of buildings), in addition to resolving horizontal variability in land surface type. This project will assess the impacts of different turbulence schemes and model resolutions on flow processes likely to influence air quality, using a combination of MetUM simulations, box models and observational data. It will also include an initial assessment of whether including an urban canopy drag parametrization is likely to have a substantial impact on model accuracy.

Some links for this work:

Papers:

1. A paper on dispersion characteristics of the sub-km MetUM.
2. A paper on turbulence characteristics of the urban canopy.
3. PhD thesis by Lewis Blunn.

Talks:

1. An invited talk on simulating dispersion in the convective boundary layer, (presented by Lewis Blunn), for the Urban Fluid Mechanics Special Interest Group.
2. A talk on modelling velocity and scalar profiles in urban canopies, (presented by Lewis Blunn), at the 21st Joint Conference on the Applications of Air Pollution Meteorology in Boston.
3. A talk on modelling velocity and scalar profiles in urban canopies, (presented by Lewis Blunn), at an NCAS air quality symposium in Leeds.
4. A talk on implications of turbulence representation for pollution modelling, (presented by Lewis Blunn), at a RMetS/NCAS conference in York.

Posters:

1. A poster on tracer dispersion in urban areas, (presented by Lewis Blunn), at the annual Fluids conference in Manchester.
2. A poster on box modelling of urban air quality, (presented by Lewis Blunn), at the Royal Met Soc student conference in Exeter. The same poster was presented at the NCAS staff conference in Manchester, and received the prize for the best poster presentation in the Models and Data section.

Others:

1. A blog entry on high-resolution dispersion modelling