Developing high-resolution NWP for local-scale air quality prediction over cities

London’s air quality regularly breaches EU standards - for instance, the annual maximum permitted number of 18 breaches of hourly limits of nitrogen dioxide was exceeeded in the first week of 2016 alone (The Guardian, 8 Jan 2016). Given recent, compelling evidence of the health impacts of air pollution, accurate local air quality forecasting is now a priority, but depends critically on high-resolution numerical weather prediction (NWP) capability. The UK Met Office is developing the Unified Model (MetUM) to run at O(1 km - 100 m) resolutions, with particular focus on London, Beijing and Shanghai. However, it is currently 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 impact 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.

Full project description is available at http://www.met.reading.ac.uk/pg-research/phdtemplate2016_NWP-AQ.pdf

Project co-supervised by Dr Bob Plant and Prof Janet Barlow (University of Reading) and Dr Sylvia Bohnenstengel and Dr Humphrey Lean (Met Office)