Ozone attributed to Madrid and Barcelona on-road transport emissions: Characterization of plume dynamics over the Iberian Peninsula

摘要

Despite the ～30% emission decrease of the main tropospheric ozone (O_3) precursors in Spain in the 2001-2012 period, the O_3 concentration in summer still exceeds the target value for the protection of the human health of the Air Quality Directive (2008/50/EC). On-road transport is the main anthropogenic contributor to O_3 precursor's emissions in Madrid and Barcelona metropolitan areas (65%/59% of NO_x, 40%/33% of NMVOC, and 67%/85% of CO emissions) but this contribution to O_3 formation is not well understood. The present work aims at increasing the understanding on the role of on-road transport emissions from main Spanish urban areas in O_3 dynamics over Spain under typical circulation types. For that purpose, the Integrated Source Apportionment Method is used within the CALIOPE modelling system (WRF/CMAQ/HERMES/BSC-DREAM8b). The results indicate that the daily maximum O_3 concentration attributed to the on-road transport emissions from Madrid (O_(3T-MAD)) and Barcelona metropolitan areas (O_(3T-BCN)) contribute up to 24% and 8% to total O_3 concentration, respectively, within an area of influence of 200 km. The contribution of O_(3T-MAD) and O_(3T-BCN) is particularly significant (up to 80-100 μg m~(-3) in an hour) to the O_3 concentration peak during the central hours of the day in the high O_3 concentration season (April-September). The maximum O_(3T-MAD) concentration is calculated within the metropolitan area of Madrid but the plume, channelled by the Tajo and the Henares valleys, affects large areas of the Iberian Peninsula. The O_(3T-BCN) plume is more driven by sea-land and mountain-valley breezes than by the synoptic advection and its maximum concentration is usually registered over the Mediterranean Sea. The O_3 concentration transported long-range to the Iberian Peninsula is significant in the area of influence of Madrid and Barcelona, being maxima under cold (70-96%) and minima in warm circulation types (35-70%).