Chemical-transport model CMAQ
The chemical-transport model CMAQ (Community Multiscale Air Quality modeling system) is a freely available air quality model developed at the EPA National Laboratory for Exposure Research, which is part of the largest research park in the USA - Research Triangle Park.
CMAQ is a regional model - its spatial resolution ranges from a few hundred meters to tens of kilometers. The output of the model are 4D fields of pollutants for the selected area, as well as their dry and wet deposition (removal of pollutants from the atmosphere), typically with an hourly resolution.

Input data for CMAQ are 4D fields of meteorological parameters (temperature, pressure, wind, ...) and also emissions from various sources (household heating, transport, industry, system energy, agriculture) with an hourly time resolution.
The model output is calculated based on a system of integro-differential equations. These equations are calculated at each point of a regular 3D grid covering the modeled area at each step of the simulation. The physical equations in the model describe the transport and change of state of pollutants, as well as dry and wet deposition. Atmospheric chemistry equations describe the chemical transformation of pollutants, which is important in the formation of atmospheric ozone and secondary particulate matter, but also in other reactions of gaseous pollutants.

At SHMÚ we are currently working at SHMÚ with a spatial resolution of 2x2 km within the CMAQ model. Of all the models we use, CMAQ has the greatest demand on computing resources.
Examples of the outputs of the CMAQ model for Slovakia are shown in Fig. 1 - 4.
Fig. 1 and Fig. 3 show outputs for simulations run with selected emission sectors (household heating or road transport), on Fig. 2 and 4 are the outputs of the CMAQ model for a simulation with all sources and with boundary conditions that include long-distance transmission.

Koncentrácie PM10 z vykurovania domácností, výstup modelu CMAQ.

Fig. 1 Hourly mean PM10 from domestic heating, the CMAQ model output.
Priemrné hodinové koncentrácie PM10, výstup modelu CMAQ.
Fig. 2 Total ourly mean PM10, the CMAQ model output.
Koncentrácie NO2 z cestnej dopravy
Fig. 3 Hourly mean NO2 from road transport, the CMAQ model output.

priemerné hodinové koncentrácie NO2, výstup modelu CMAQ
Fig. 4 Total hourly mean NO2, the CMAQ model output.