MAQS

Multi-Model Air Quality System

Model input data

Meso-scale meteorological model data

MAQS links directly to meteorological data output files generated by the WRF meso-scale meteorological model. These files should contain the same data as used to run the regional air quality model, to ensure consistency between the regional and local components of the system. MAQS automatically identifies the correct data file for each hour of the modelling period following a user-defined date- and time-dependent naming convention.

MAQS links to meteorological data from other mesoscale meteorological models via a 'generic' input data format.

Regional model concentration data

MAQS links directly to output files from the CMAQ, CAMx (converted to I/O API), CHIMERE, EMEP and WRF-Chem regional chemical transport air quality models. The regional model output data should cover the required MAQS modelling domain with a buffer of one cell in each direction. The regional model grid must be regular in a projected coordinate system with units of metres. As the more detailed chemistry schemes used for regional modelling include a larger number of chemical species than are typically used in ADMS-Urban, a species map file is used to define how the regional model and ADMS-Urban pollutant species are related, including any required unit conversion factors.

MAQS links to concentration data from other regional chemical transport models via a 'generic' input data format.

Emissions

In addition to the standard emissions data which is required to model an urban area using ADMS-Urban, for MAQS, gridded emissions data consistent with that used in the regional model must be processed in order to obtain valid nesting background concentrations. Both the total emission rates and the time-variation of emissions should be matched as closely as possible to the regional model equivalents. 3D gridded emissions as used in the CMAQ and WRF-Chem models can automatically be converted for use in ADMS-Urban.

CERC's EMIT emissions database tool can generate hourly 3D emissions grids for import into MAQS, for example from 2D annual average gridded emissions data categorised according to source sector, and associated temporal and vertical disaggregation profiles.

Local modelling parameters

ADMS-Urban model parameter file(s) must be set up containing local source emissions, for example explicitly-modelled road sources, and specification of the required output locations and pollutant species.

Model output data

The output files from MAQS contain hourly concentrations at each output location in the portable netCDF format. The system is also supplied with a utility to extract statistics such as percentiles to ADMS-format text files, which can then be used in the standard ADMS-Urban contour plotting utilities and the Model Evaluation Toolkit.

As with ADMS-Urban, source-oriented gridding can be included in MAQS in order to create high-resolution contour plots of concentrations.

MAQS includes an output data post-processor tool that allows users to generate interpolated concentrations for visualisation, including options for temporal and/or spatial aggregation and subsetting.

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