The METRAS model has originally been developed at Meteorological Institute, University of Hamburg (Schlünzen, 1988, 1990). In the meantime it is broadly used in Germany and overseas. METRAS can be used for areas between 10x10  km² (e.g. convection) and 2500x2500 km² (e.g. coastal convergences, pollution transport in a regional scale, cyclone development). A 3D non-uniform grid allows higher resolution in interesting areas and close to the surface with a reduced resolution in other regions. Wind, temperature, humidity, cloud- and rainwater as well as tracer concentrations are calculated from prognostic equations, pressure from the (diagnostic) anelastic equation. The influence of several land use characteristics (e.g. water, urban areas, vegetation, ice) as well as of orography (mountains, cliffs, houses) is considered in the model using flux averaging with blending height concept. The dry deposition of pollutions is calculated from a resistance model, it depends on pollution and land use characteristics. Chemical transformations are included in the off-line coupled chemistry transport  model MECTM .

The lateral model boundaries are open or METRAS is nested in results of a coarser model (e.g. weather forecast, analysis or regional climate model). At the model top absorbing layers are used, or again the nesting technique is applied. By use of the model system M-SYS which employs METRAS and MECTM in several resolutions concentrations of several pollutants (e.g. NO_x, O₃, SO₂ , NH₃, Pb, nitrate, sulphate) in the air and the deposition at the ground can be calculated dependent on the sources (industry, power stations, household, car and ship traffic). Emission scenario studies can be performed.

• Meteorological Institute, Centre for Marine and Atmospheric Research, University of Hamburg, Germany
• Alfred-Wegener-Institute for Polar and Marine Research, Bremerhaven, Germany
• Forschungszentrum Jülich, Abt. Sicherheit und Strahlenschutz, Germany
• Rechenzentrum, Univerität Karlsruhe, Germany
• Institut für Physik und Meteorologie, Universität Hohenheim, Stuttgart, Germany
• Ocean University of Qingdao, PR China
• Division of Environmental Health and Risk Management, School of Geography, Earth and Environmental Sciences, University of Birmingham, UK
• University of Duisburg-Essen, Campus Essen, Applied Climatology and Landscape Ecology
• Freie Universitaet Berlin, Insitute of Meteorology
• Public Domain Version METRAS PCL

• Simulation of coastal atmospheric processes including aerosol 
• Mesoscale modelling of the atmosphere in North Atlantic regions
• Determination of the sensitivity of three-dimensional mesoscale chemical transport models
• Development and application of a validation concept for high-resolution chemistry transport models(ended 6/99)
• Development of a PC version of the mesoscale model METRAS (ended 4/98)
• Modelling of small-scale meteorological phenomena in the coastal area (ended 9/97)

• Forecast of small scale atmospheric phenomena for Lower Saxony
• Relevance of sea-ice formation for the development of polar cyclones
• Cyclone development in the area of polynias
• Evaluation of the mesoscale transport- and fluid-model METRAS (ended 10/97)

• Influence of aerosol formation on nitrogen input in coastal areas
• Simulation of pollen transport using an atmospheric model
• Influence of coastal atmospheric phenomena on nitrogen input in coastal regions
• Water and energy budget for the Arctic atmosphere (ended 04/02)
• Mesoscale and large scale influences on the development of small scalemesoscale systems over the North Atlantic (ended 01/02)
• On the application of Kalman filters and nudging methods in atmospheric data assimilation (ended 06/01)
• Wind regimes and air pollution transport over Qingdao area (ended 04/00)
• Development and application of a model for the dynamics and composition of secondary and marine aerosols (ended 9/97)