Articles | Volume 8, issue 7
Atmos. Meas. Tech., 8, 2715–2736, 2015
Atmos. Meas. Tech., 8, 2715–2736, 2015

Research article 08 Jul 2015

Research article | 08 Jul 2015

ACTRIS non-methane hydrocarbon intercomparison experiment in Europe to support WMO GAW and EMEP observation networks

C. C. Hoerger1, A. Claude2, C. Plass-Duelmer2, S. Reimann1, E. Eckart3, R. Steinbrecher3, J. Aalto4, J. Arduini5, N. Bonnaire6, J. N. Cape7, A. Colomb8, R. Connolly9, J. Diskova10, P. Dumitrean11, C. Ehlers12, V. Gros6, H. Hakola13, M. Hill1, J. R. Hopkins14, J. Jäger12, R. Junek15, M. K. Kajos16, D. Klemp12, M. Leuchner17, A. C. Lewis14, N. Locoge18, M. Maione5, D. Martin19,20, K. Michl2, E. Nemitz7, S. O'Doherty17, P. Pérez Ballesta9, T. M. Ruuskanen16, S. Sauvage18, N. Schmidbauer21, T. G. Spain20, E. Straube15, M. Vana10,22, M. K. Vollmer1, R. Wegener12, and A. Wenger1,19 C. C. Hoerger et al.
  • 1Swiss Federal Laboratories for Materials Science and Technology (Empa), Dübendorf, Switzerland
  • 2Deutscher Wetterdienst, Hohenpeissenberg, Germany
  • 3Karlsruhe Institute of Technology (KIT), Campus Alpin, Garmisch-Partenkirchen, Germany
  • 4Department of Forest Sciences, University of Helsinki, Helsinki, Finland
  • 5Department of Environmental Science, University of Urbino "Carlo Bo", Urbino, Italy
  • 6Laboratoire des Sciences du Climat et de l'Environnement, Gif sur Yvette, France
  • 7Centre for Ecology & Hydrology, Penicuik, UK
  • 8Observatoire de Physique du Globe de Clermont-Ferrand, Aubière, France
  • 9European Commission Joint Research Centre, Ispra, Italy
  • 10Czech Hydrometeorological Institute, Prague, Czech Republic
  • 11Ricardo-AEA, Oxon, UK
  • 12Institute of Energy and Climate Research, Troposphere (IEK-8), Forschungszentrum Jülich, Jülich, Germany
  • 13Finnish Meteorological Institute, Helsinki, Finland
  • 14National Centre for Atmospheric Science (NCAS), University of York, York, UK
  • 15Umweltbundesamt, Station Schmücke, Gehlberg, Germany
  • 16Department of Physics, University of Helsinki, Helsinki, Finland
  • 17Fachgebiet für Ökoklimatologie, Technische Universität München, Freising, Germany
  • 18Ecole des Mines de Douai, Douai, France
  • 19School of Chemistry, University of Bristol, Bristol, UK
  • 20School of Physics and Centre for Climate and Air Pollution Studies, National University of Ireland, Galway, Ireland
  • 21Norwegian Institute for Air Research (NILU), Kjeller, Norway
  • 22Global Change Research Centre, Academy of Sciences of the Czech Republic, Brno, Czech Republic

Abstract. The performance of 18 European institutions involved in long-term non-methane hydrocarbon (NMHC) measurements in ambient air within the framework of the Global Atmosphere Watch (GAW) and the European Monitoring and Evaluation Programme (EMEP) was assessed with respect to data quality objectives (DQOs) of ACTRIS (Aerosols, Clouds, and Trace gases Research InfraStructure Network) and GAW. Compared to previous intercomparison studies the DQOs define a novel approach to assess and ensure a high quality of the measurements. Having already been adopted by GAW, the ACTRIS DQOs are demanding with deviations to a reference value of less than 5 % and a repeatability of better than 2 % for NMHC mole fractions above 0.1 nmol mol−1. The participants of the intercomparison analysed two dry gas mixtures in pressurised cylinders, a 30-component NMHC mixture in nitrogen (NMHC_N2) at approximately 1 nmol mol−1 and a whole air sample (NMHC_air), following a standardised operation procedure including zero- and calibration gas measurements. Furthermore, participants had to report details on their instruments and assess their measurement uncertainties. The NMHCs were analysed either by gas chromatography–flame ionisation detection (GC-FID) or by gas chromatography–mass spectrometry (GC-MS). For the NMHC_N2 measurements, 62 % of the reported values were within the 5 % deviation class corresponding to the ACTRIS DQOs. For NMHC_air, generally more frequent and larger deviations to the assigned values were observed, with 50 % of the reported values within the 5 % deviation class. Important contributors to the poorer performance in NMHC_air compared to NMHC_N2 were a more complex matrix and a larger span of NMHC mole fractions (0.03–2.5 nmol mol−1). The performance of the participating laboratories were affected by the different measurement procedures such as the usage of a two-step vs. a one-step calibration, breakthroughs of C2–C3 hydrocarbons in the focussing trap, blank values in zero-gas measurements (especially for those systems using a Nafion® Dryer), adsorptive losses of aromatic compounds, and insufficient chromatographic separation.

Short summary
The performance of 20 European laboratories involved in long-term non-methane hydrocarbon (NMHC) measurements was assessed with respect to ACTRIS and GAW data quality objectives. The participants were asked to measure both a 30-component NMHC mixture in nitrogen and whole air. The NMHCs were analysed either by GC-FID or GC-MS. Most systems performed well for the NMHC in nitrogen, whereas in air more scatter was observed. Reasons for this are explained in the paper.