Extreme PM and Ozone Pollution over Central Europe: Interactions of the Urban Canopy Meteorological Forcing and Radiative Effects of Urban Emissions
Abstract
Extreme air pollution in European cities persists today, being a large health burden on their inhabitants. Understanding the processes that control or modulate such events over urban areas is therefore crucial.
In this study, based on two air pollution events in August 2015 and January 2017, it is examined the mutual role of urban emissions (and secondary pollutants formed from them) and the urban canopy meteorological forcing (UCMF) over central Europe in influencing urban air quality over eight selected central European cities. Series of WRF-Chem simulations with/without urban land-surface and with/without urban emissions were performed, and the impact on meteorological conditions and chemical species was examined in the selected European cities.
As for the impact on meteorological conditions, results have shown that they depend much more on the direct effect of the UCMF than on the secondary effects of the radiative impacts of urban emissions, which occurred via aerosol (in)-direct effects. It has also been shown that these radiative impacts depend whether the UCMF is included or not.
Regarding the impact on chemical concentrations, it is driven especially by emissions causing increase in PM and NO2 and decrease in ozone, and the UCMF, causing decrease in PM and NO2 and increase in ozone, while the indirect effects of urban emission-induced meteorological changes (via radiation) are substantially smaller.