Chemical and dynamical identification of emission outflows during the HALO campaign EMeRGe in Europe and Asia

[摘要] The number of large urban agglomerations is steadilyincreasing worldwide. At a local scale, their emissions lead to airpollution, directly affecting people's health. On a global scale, theiremissions lead to an increase of greenhouse gases, affecting climate. Inthis context, in 2017 and 2018, the airborne campaign EMeRGe (Effect ofMegacities on the transport and transformation of pollutants on the Regionalto Global scales) investigated emissions of European and Asian majorpopulation centres (MPCs) to improve the understanding and predictability ofpollution outflows. Here, we present two methods to identify andcharacterise pollution outflows probed during EMeRGe. First, we use a set ofvolatile organic compounds (VOCs) as chemical tracers to characterise airmasses by specific source signals, i.e. benzene from anthropogenic pollutionof targeted regions, acetonitrile from biomass burning (BB, primarily duringEMeRGe-Asia), and isoprene from fresh biogenic signals (primarily duringEMeRGe-Europe. Second, we attribute probed air masses to source regions andestimate their individual contribution by constructing and applying a simpleemission uptake scheme for the boundary layer which combines FLEXTRA backtrajectories and EDGAR carbon monoxide (CO) emission rates (acronyms areprovided in the Appendix). During EMeRGe-Europe, we identified anthropogenicpollution outflows from northern Italy, southern Great Britain, theBelgium–Netherlands–Ruhr (BNR) area and the Iberian Peninsula. Additionally, ouruptake scheme indicates significant long-range transport of pollution fromthe USA and Canada. During EMeRGe-Asia, the pollution outflow is dominatedby sources in China and Taiwan, but BB signals from Southeast Asia and Indiacontribute as well. Outflows of pre-selected MPC targets are identified inless than 20 % of the sampling time, due to restrictions in flightplanning and constraints of the measurement platform itself. Still, EMeRGecombines in a unique way near- and far-field measurements, which showsignatures of local and distant sources, transport and conversionfingerprints, and complex air mass compositions. Our approach provides avaluable classification and characterisation of the EMeRGe dataset, e.g. forBB and anthropogenic influence of potential source regions and paves theway for a more comprehensive analysis and various model studies.

[学科分类] 医学（综合）