Met Office Dispersion Model

The Met Office's Numerical Atmospheric-dispersion Modelling Environment (NAME) is used to model a wide range of atmospheric dispersion events.

NAME is a sophisticated tool capable of simulating many atmospheric dispersion phenomena and associated physical and chemical processes. NAME is capable of both forward and inverse (source identification) simulations.

NAME is used by the Met Office to model a wide range of atmospheric dispersion events including nuclear accidents, volcanic eruptions, chemical accidents, smoke from fires, odours, airborne animal diseases, as well as the provision of routine air quality forecasts. In inverse mode the model is used to investigate emissions of greenhouse gases and other atmospheric pollutants. The model is used for research activities and for emergency air pollution forecasts.

NAME uses the Met Office Unified Model and ECMWF Numerical Weather Prediction (NWP) meteorology data. Both forecast and archived data are available, enabling forecasts out to 10 days and historic studies back to 1957. There is no limitation to the duration of a pollutant release or the time period covered by a NAME simulation. It is therefore possible to predict dispersion over distances ranging from a few kilometres to the whole globe and for time periods of minutes to decades.

NAME is a Lagrangian particle model which calculates the dispersion by tracking model 'particles' through the modelled atmosphere. These particles move with the resolved wind described by the meteorology, which can vary in space and time. The particles' motion also has a random component to represent the effects of atmospheric turbulence. A consequence of this is that no assumptions need to be made for the shape of the concentration distribution, such as are required in Gaussian plume models. Pollutants can also be removed from the model atmosphere by several processes: (i) fall out due to gravity, (ii) impaction with the surface, (iii) washout where the pollutant is 'swept out' by falling precipitation, and (iv) "rainout" where the pollutant is absorbed directly into cloud droplets as they form. In addition each model 'particle' can have its own characteristics; for example particles can represent different compounds or chemicals, and particles can have real particulate sizes.

An overview of the latest generation of the model (NAME III) is presented by Jones et al. (2007).

Model Features

Air Concentrations

  • 3D particle dispersion or splitting puffs
  • Forward or backward simulations
  • Sources:
    • Unlimited number of sources
    • Unlimited number of species on different/same sources
    • Each source can be instantaneous or of any arbitrary duration
    • Emissions can be constant or have user defined time varying properties
    • Sources can be point, line, area or volume with the geometry of cuboid, ellipsoid or cylindroid
  • Processes:
    • Wet deposition (both in cloud and below cloud) and dry deposition
    • Gravitational settling
    • Radioactive processes: radioactive decay, decay chains, cloud gamma
    • Chemical/biological agent decay
    • Plume rise
    • Air quality based chemistry scheme (36 reactive species)
    • Resuspension of sand and sea salt
  • Output:
    • Unlimited number of different resolution uniform grids
    • Unlimited number of unstructured (non-uniformly spaced) output grids e.g. points for time series output
    • Time averaged and integrated concentrations
    • Concentration probabilities and percentiles
    • Travel time - particle and grid box mean
    • Particle position plus associated characteristics and meteorology
  • General:
    • Ensemble prediction system and associated statistics contained in single model run
    • Fully flexible horizontal and vertical coordinate systems.
    • Multiple predefined coordinate systems including: lat-long, UK National Grid, metres above ground/sea, Flight Levels, pressure-based vertical systems.
    • Ability for user to define own coordinate systems.

Trajectories

  • Single or multiple (space or time) mean and turbulent simultaneous trajectories
  • Forward or backward simulations
  • Output of meteorological variables along a trajectory

Meteorology

  • Model can run with multiple nested (temporally and spatially) input meteorological data
  • Uses both forecast and archived deterministic and ensemble NWP data from:
    • Met Office Unified Model
    • ECMWF (Operational deterministic and ensemble forecasts, ERA Interim, ERA40)
  • Uses single site observed meteorological data for short range applications
  • Can use radar rainfall rates

Programming Environment

  • FORTRAN 90/95 standard
  • Modular code design
  • openmp parallelisation
  • Compilers:
    • Supported: Intel
    • Unsupported but used: Sun Solaris, IMB XL FORTRAN, Compaq and Portland
  • Operating systems:
    • Supported: Linux, MS Windows
    • Unsupported but used: Apple Mac, Sun, IBM HPC

How can you use NAME?

NAME is available for external research use under licence. A number of UK Universities, UK government agencies and the South African Weather Service use NAME in collaboration with the Met Office to undertake dispersion based research.
 
Further information on how to apply for a licence can be obtained by contacting the Met Office.

References

Jones A.R., Thomson D.J., Hort M. and Devenish B., 'The U.K. Met Office's next-generation atmospheric dispersion model, NAME III', in Borrego C. and Norman A.-L. (Eds) Air Pollution Modeling and its Application XVII (Proceedings of the 27th NATO/CCMS International Technical Meeting on Air Pollution Modelling and its Application), Springer, pp. 580-589, 2007.

To view PDF documents you will need Adobe Reader.
Adobe Acrobat Reader

Last updated: 22 May 2012