Overview on the Model
Based on the mesoscale model METRAS the microscale model MITRAS has been developed (Schlünzen et al., 2003). The MITRAS model has originally been developed in the tropospheric research program, funded by BMBF in a consortium of four partners. The Meteorological Institute, Centre for Ocean and Climate, Research, University of Hamburg, Germany coordinated the model development, implemented the modules developed within the consortium into MITRAS and was responsible for model validation. Data sets tailored for model validation were created in the wind tunnel (CEDVAL). Turbulence was provided by Alfred-Wegener-Institute for Polar and Marine Research, Bremerhaven, Germany (Lopez et al., 2005); Institute for Tropospheric Research, Leipzig, Germany, developed the numerical schemes and an extension of the gas phase chemistry to consider soot transport, the gas phase chemistry itself was developed by Fraunhofer-Institut for Atmospheric Environmental Research, Garmisch-Partenkirchen, Germany. Forschungszentrum Jülich added vegetation effects to MITRAS. Since computing time for on-line coupling was too large a consistent off-line chemistry model MICTM has been developed based on the chemistry model MECTM. MITRAS can be used for areas between 100x100 m2 (e.g. flow around one building) and 1000x1000 m2 (e.g. suburb, part of a city). A 3D non-uniform vertical grid allows higher resolution in interesting areas, e.g. close to an interesting crossing and close to the surface and 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. In the model obstacles (buildings, trees etc.) are resolved using the blocking approach for buildings and viscosity approach for vegetation. The influence of unresolved land use characteristics (e.g. water, soil, grass) is considered in the surface fluxes, orography is considered by using a surface following model grid. The lateral model boundaries are open or inflow values may be prescribed. At the model top absorbing layers are used. By use the MITRAS model output in MECTM concentrations of several pollutants (e.g. NOx, O3, SO2 , NH3, Pb, nitrate, sulphate) including their chemical transformations can be calculated dependent on the sources (industry, power stations, household, traffic). Emission scenario studies can be performed. MITRAS is part of the model system M-SYS.
- Division of Environmental Health and Risk Management, School of Geography, Earth and Enivonmental Sciences, University of Birmingham, UK
- Development and validation of a prognostic microscale model for the canopy layer
- Data assimilation in chemistry transport models
- Relevance of thermal effects for street canyon flows