Abstract
Top-down estimates of surface NOX emissions were derived for 23 European cities based on the downwind plume decay of tropospheric nitrogen dioxide (NO2) columns from the LOTOS-EUROS (Long Term Ozone Simulation-European Ozone Simulation) chemistry transport model (CTM) and from Ozone Monitoring Instrument (OMI) satellite retrievals, averaged for the summertime period (April–September) during 2013. Here we show that the top-down NOX emissions derived from LOTOS-EUROS for European urban areas agree well with the bottom-up NOX emissions from the MACC-III inventory data (R2 = 0.88) driving the CTM demonstrating the potential of this method. OMI top-down NOX emissions over the 23 European cities are generally lower compared with the MACC-III emissions and their correlation is slightly lower (R2 = 0.79). The uncertainty on the derived NO2 lifetimes and NOX emissions are on average ~55% for OMI and ~63% for LOTOS-EUROS data. The downwind NO2 plume method applied on both LOTOS-EUROS and OMI tropospheric NO2 columns allows to estimate NOX emissions from urban areas, demonstrating that this is a useful method for real-time updates of urban NOX emissions with reasonable accuracy.
Highlights
High levels of nitrogen oxides (NOX = NO + NO2 ) are toxic and adversely impact both human health [1] and ecosystems [2,3]
The downwind NO2 plume method applied on both LOTOS-EUROS and Ozone Monitoring Instrument (OMI) tropospheric NO2 columns allows to estimate NOX emissions from urban areas, demonstrating that this is a useful method for real-time updates of urban NOX emissions with reasonable accuracy
For the cities the effective NO2 lifetime is 4.1 ± 2.2 h derived from OMI tropospheric
Summary
High levels of nitrogen oxides (NOX = NO + NO2 ) are toxic and adversely impact both human health [1] and ecosystems [2,3]. NOX is mainly generated in polluted regions by anthropogenic combustion of fuels from traffic, industrial processes and household activities that typically occur in densely populated urban areas. Environment Agency, around 10% of the urban population in the EU-28 is exposed to air pollutant concentrations above EU and WHO reference levels (2011–2013) for NO2 [4]. Since 86% of the exceedances are measured at traffic stations, the percentage of the urban population exposed to high. NO2 concentrations may be somewhat underestimated as >20% of the European urban population. Millions of people may potentially suffer from health issues and loss of productive labour
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