CERC — Environmental Software and Services

ADMS-Urban RML icon


ADMS-Urban nested within regional air quality models

What is the ADMS-Urban RML?

ADMS-Urban RML combines ADMS-Urban with an innovative regional model link (RML) to provide automated nesting of ADMS-Urban within data from regional meteorological and air quality models. Supported model formats are WRF for meteorology data and CMAQ, CAMx, CHIMERE, EMEP4UK or WRF-Chem for air quality data. The output from the ADMS-Urban RML system contains predictions of pollutant concentrations for an urban area, taking into account both regional and local pollutant transport and chemistry effects.

The ADMS-Urban RML system runs on Linux and comprises:

  • ADMS-Urban dispersion model
  • tools to process the regional model data
  • software to automate running these components

The system is also supplied with an ADMS-Urban Windows interface for composing ADMS-Urban RML input files.

Typical applications of the ADMS-Urban RML include:

  • developing and testing the impact of regional and local air quality management policies on pollutant concentrations throughout a complex urban area
  • exposure assessments
  • provision of detailed street-scale air quality forecasts for an urban area in combination with a regional scale forecast for surrounding rural area

Who uses the ADMS-Urban RML?

Image of Hong Kong NO2 forecast concentration contours for 2017

Forecast NO2 concentrations contours from CMAQ (left) and ADMS-Urban RML (right) for the main urban areas of Hong Kong and Kowloon, for 3 pm local time on 13th October 2017.

The ADMS-Urban RML system is for current users of regional air dispersion models who wish to increase the resolution of their modelling over urban areas to take account of street-scale concentration gradients in a computationally efficient way, and for users of ADMS-Urban who wish to take into account spatially-varying meteorology and background concentrations from regional modelling. The design of the system allows the regional modelling and the local modelling to be performed separately, facilitating collaborations between regional and local modelling specialists and allowing a single set of regional modelling data to be used to test many local modelling scenarios.

Pioneering uses of the ADMS-Urban RML include:

  • The ADMS-Urban RML has been set up to model the Hong Kong Special Administrative Region for the Hong Kong Environmental Protection Department. Regional model data was taken from the CAMx model run by researchers from the Hong Kong University of Science and Technology (HKUST). The PRAISE-HK project is generating daily street-scale forecasts for Hong Kong using the ADMS-Urban RML driven by regional CMAQ forecasting.
  • Researchers at the University of Edinburgh’s Contemporary Climate group use the ADMS-Urban RML with the EMEP4UK regional model to investigate the effects of future climate scenarios on local air quality in London and across the UK.
  • CERC are collaborating with the University of Birmingham in the WM-Air project, which will use the ADMS-Urban RML to model street-scale air quality in the West Midlands region of the UK.
  • CERC’s partners in France, NUMTECH, are planning to combine their experience of using ADMS-Urban and the regional model CHIMERE by using the ADMS-Urban RML system to improve modelling of complex urban environments in France.

Why use ADMS-Urban RML?

Nesting the local model ADMS-Urban within a regional model using the ADMS-Urban RML allows both the resolution of high concentration gradients close to a source, and the accurate representation of transport and chemistry over larger spatial and temporal scales. The ADMS-Urban RML system combines the regional and local concentrations in such a way as to minimise double-counting of emissions, while remaining computationally efficient and user-friendly.

The principal features of the ADMS-Urban RML system are:

  • An automated control system with logging of progress to file and screen
  • Option for use of the GNU Parallel approach for distributing runs across multiple machines
  • Compatibility with CMAQ, CAMx, CHIMERE, EMEP4UK and WRF-Chem regional air pollution models, with potential for extension to other regional models
  • Automatic division of a large nesting domain into separate runs for each regional model grid cell, with appropriate local meteorology from the WRF meso-scale model and background concentrations
  • Flexibility regarding the size and shape of the nesting domain
  • No requirement to re-run the regional air quality or meteorological models
  • Inclusion of advanced modelling techniques for urban areas, such as street canyon and urban canopy flow field calculations, through the use of ADMS-Urban


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