19 Jul 2022
19 Jul 2022
Status: this preprint is currently under review for the journal ACP.

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

Eric Förster1, Harald Bönisch1, Marco Neumaier1, Florian Obersteiner1, Andreas Zahn1, Andreas Hilboll3,, Anna Beata Kalisz Hedegaard2,3, Nikos Daskalakis3, Alexandros Panagiotis Poulidis3, Mihalis Vrekoussis3,4,5, Michael Lichtenstern2, and Peter Braesicke1 Eric Förster et al.
  • 1KIT - Karlsruhe Institute of Technology, Institute of Meteorology and Climate Research, Karlsruhe, Germany
  • 2DLR IPA - Deutsches Zentrum für Luft- und Raumfahrt, Institut für Physik der Atmosphäre, Oberpfaffenhofen, Germany
  • 3IUP Bremen - Institut für Umweltphysik, Universität Bremen, Bremen, Germany
  • 4Center for Marine Environmental Sciences (MARUM), University of Bremen, Bremen, Germany
  • 5Energy, Environment and Water Research Centre, The Cyprus Institute (CyI), Nicosia, Cyprus
  • deceased

Abstract. Worldwide the number of large urban agglomerations is steadily increasing. At a local scale, their emissions lead to air pollution, directly affecting people’s health. On a global scale, their emissions lead to an increase of greenhouse gases, affecting climate. In this context, in 2017 and 2018, the airborne campaigns EMeRGe (Effect of Megacities on the transport and transformation of pollutants on the Regional to Global scales) investigated emissions of European and Asian major population centres (MPCs) to improve the understanding and predictability of pollution outflows. Here, we present two methods to identify and characterise emission outflows probed during EMeRGe. First, we use a set of volatile organic compounds (VOCs) as chemical tracers to characterise air-masses by specific source signals, i.e. benzene from anthropogenic emissions of targeted regions, acetonitrile from biomass burning (BB, primarily during EMeRGe-Asia) and isoprene from fresh biogenic signals (primarily during EMeRGe-Europe). Second, we attribute probed air-masses to source regions and estimate their individual contribution by constructing and applying a simple emission uptake scheme for the boundary layer which combines FLEXTRA back-trajectories and EDGAR carbon monoxide (CO) emission rates (acronyms are provided in Appendix A). During EMeRGe-Europe, we identified anthropogenic emission outflows from Northern Italy, Southern Great Britain, the Belgium-Netherlands-Ruhr area and the Iberian Peninsula. Additionally, our uptake scheme indicates significant long-range transport of emissions from the USA and Canada. During EMeRGe-Asia, the emission outflow is dominated by sources in China and Taiwan, with further emissions (mostly from BB) originating from Southeast Asia and India. Emissions of pre-selected MPC targets are identified in less than 20 % of the sampling time, due to restrictions in flight planning and constraints of the measurement platform itself. Still, EMeRGe combines in a unique way near- and far-field measurements, which show signatures of local and distant sources, transport and conversion fingerprints and complex emission mixtures. Our approach already provides a valuable classification and characterisation of the EMeRGe dataset, e.g. for BB and anthropogenic influence of potential source regions, and paves the way for a more comprehensive analysis and various model studies.

Eric Förster et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'comment', Anonymous Referee #1, 22 Sep 2022
    • AC1: 'Reply on RC1', Eric Förster, 25 Nov 2022
  • RC2: 'Comment on acp-2022-455', Anonymous Referee #2, 01 Oct 2022
    • AC2: 'Reply on RC2', Eric Förster, 25 Nov 2022

Eric Förster et al.

Eric Förster et al.


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Short summary
The airborne megacity campaign EMeRGe provided an unprecedented amount of trace gas measurements. We combine measured volatile organic compounds (VOCs) with trajectory-modelled emission uptakes to identify potential source regions of pollution. We also characterise the chemical fingerprints (e.g. biomass burning and anthropogenic signatures) of the probed air-masses to corroborate the contributing source regions. Our approach is the first large-scale study of VOCs originating from megacities.