An urban scale air quality forecast system developed in Finnish Meteorological Institute (FMI) provides 44 hour forecasts for NO2, NO, CO, PM2.5, PM10, and O3 four times a day for the Helsinki metropolitan area.

The main processes to model local air quality are the traffic emission, dispersion and chemistry models of CAR-FMI (Härkönen, 2002) and the road dust emission model FORE (Kauhaniemi et al., 2011). The system contains also several meteorological and air quality data retrieval and storage services. The forecasted meteorological and background concentration data are from the operative HIRLAM and SILAM runs, and the latest air quality observations of Helsinki Region Environmental Services Authority (HSY) are gathered via FMI open data service. Besides the dynamic meteorological and air quality data, the static input data include exhaust emission factors, and traffic volume and speed data for the main vehicle categories (passenger cars and vans, buses, and trucks), as well as, geographic information (x,y,z) of about 7700 line sources and 18700 receptor points.


Härkönen, J., 2002. Regulatory dispersion modelling of traffic-originated pollution, Finnish Meteorological Institute Contributions 38, Helsinki, University press, ISBN 951-697-564-X, 103 p.

Kauhaniemi, M., Kukkonen, J. Härkönen J., Nikmo J., Kangas L., Omstedt G., Ketzel M., Kousa A., Haakana M., Karppinen A., 2011. Evaluation of a road dust suspension model for predicting the concentrations of PM10 in a street canyon. Atmospheric Environment, 45, 3646-3654.


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