Air quality modelling over the Eastern Mediterranean: Seasonal sensitivity to anthropogenic emissions

Abstract

We employ the online coupled WRF/Chem model to study air pollution over the eastern Mediterranean during winter and summer. We utilize three nested domains with horizontal resolutions down to 2 km, over the area of interest. Dust, sea-salt, and biogenic emissions are calculated online, while anthropogenic emissions are based on the EDGAR HTAP global emission inventory. A new, up-to-date and high spatiotemporal resolution anthropogenic emission inventory for the high-resolution domain has been implemented. Its impact on the model skill to simulate the concentrations of atmospheric pollutants at background and urban sites over Cyprus, being strongly affected by polluted air masses of different origin and composition over the year, is examined. The model output from three simulations over the innermost domain using the EDGAR emission inventory, the new emission inventory, and zero emissions is compared with measurements from background and urban ground stations in Cyprus. The implementation of the updated emission inventory results in about 5% reduction in the normalized mean bias between the modelled and observed CO mixing ratios. Underestimation in wintertime CO mixing ratios and PM$_{2.5}$ concentrations is attributed to missing residential heating sources from the emission inventory, while the absence of a PM$_{2.5}$ re-suspension mechanism leads to underestimation in PM$_{2.5}$ concentrations during summer. The normalized mean bias between the modelled and observed NO$_x$ mixing ratios at the urban sites is reduced from −67% to −29% and from −51% to −10% for the winter and summer, respectively. In line with this, the overestimation in O$_3$ mixing ratios was reduced from 45% to 28% during the winter and from 25% to 19% during summer. Taking into account the diurnal variability in the emission inventory is found to be crucial for the simulation of the daily profiles of NO$_x$ and O$_3$ at urban sites, which is important both for policy making and air quality modelling.

Publication
In Atmospheric Environment.
Date
Links