Articles | Volume 5, issue 3
Atmos. Meas. Tech., 5, 657–685, 2012
Atmos. Meas. Tech., 5, 657–685, 2012

Research article 29 Mar 2012

Research article | 29 Mar 2012

Mobility particle size spectrometers: harmonization of technical standards and data structure to facilitate high quality long-term observations of atmospheric particle number size distributions

A. Wiedensohler1, W. Birmili1, A. Nowak1, A. Sonntag1, K. Weinhold1, M. Merkel1, B. Wehner1, T. Tuch1, S. Pfeifer1, M. Fiebig2, A. M. Fjäraa2, E. Asmi3, K. Sellegri4, R. Depuy4, H. Venzac4, P. Villani4, P. Laj5, P. Aalto6, J. A. Ogren7, E. Swietlicki8, P. Williams9, P. Roldin8, P. Quincey10, C. Hüglin11, R. Fierz-Schmidhauser12, M. Gysel12, E. Weingartner12, F. Riccobono12, S. Santos13, C. Grüning13, K. Faloon14, D. Beddows14, R. Harrison14, C. Monahan15, S. G. Jennings15, C. D. O'Dowd15, A. Marinoni16, H.-G. Horn17, L. Keck18, J. Jiang19, J. Scheckman19, P. H. McMurry19, Z. Deng20, C. S. Zhao20, M. Moerman20, B. Henzing21, G. de Leeuw6,3,21, G. Löschau22, and S. Bastian22 A. Wiedensohler et al.
  • 1Leibniz Institute for Tropospheric Research, Permoserstr. 15, 04318 Leipzig, Germany
  • 2Norwegian Institute for Air Research, 2027 Kjeller, Norway
  • 3Finnish Meteorological Institute, Research and Development, 00101 Helsinki, Finland
  • 4Laboratoire de Météorologie Physique, Observatoire de Physique du Globe de Clermont-Ferrand, Université Blaise Pascal, 24 avenue des Landais, 63177 Aubière, France
  • 5Laboratoire de Glaciologie et Géophysique de l'Environnement Université Joseph Fourier – Grenoble 1/CNRS, 38400 St Martin d'Hères, France
  • 6Department of Physics, University of Helsinki, 00014 Helsinki, Finland
  • 7NOAA ESRL GMD, 325 Broadway, Boulder, CO 80305, USA
  • 8Division of Nuclear Physics, Lund University, 221 00 Lund, Sweden
  • 9National Centre for Atmospheric Science, University of Manchester, Manchester, UK
  • 10Environmental Measurements Group, National Physical Laboratory, Teddington, Middlesex, UK
  • 11EMPA Dübendorf Air Pollution/Environmental Technology, Überlandstraße 129, 8600 Dübendorf, Switzerland
  • 12Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, Villigen, Switzerland
  • 13European Commission – DG Joint Research Centre, IES/CCU, Ispra, Italy
  • 14National Centre for Atmospheric Science, Division of Environmental Health & Risk Management, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
  • 15School of Physics & Centre for Climate and Air Pollution Studies, Environmental Change Institute, National University of Ireland, Galway, Ireland
  • 16Institute of Atmospheric Sciences and Climate, Via Gobetti 101, 40129 Bologna, Italy
  • 17TSI GmbH, Neuköllner Straße 4, 52068 Aachen, Germany
  • 18GRIMM Aerosol Technik GmbH & Co. KG, Dorfstraße 9, 83404 Ainring, Germany
  • 19Department of Mechanical Engineering, University of Minnesota, 111 Church Street SE Minneapolis, MN 55455, USA
  • 20Department of Atmospheric Sciences, School of Physics, Peking University, Beijing, 100871, China
  • 21TNO Built Environment and Geosciences, 3508 TA Utrecht, The Netherlands
  • 22Saxon State Office for Environment, Agriculture and Geology, Pillnitzer Platz, 01326 Dresden, Germany

Abstract. Mobility particle size spectrometers often referred to as DMPS (Differential Mobility Particle Sizers) or SMPS (Scanning Mobility Particle Sizers) have found a wide range of applications in atmospheric aerosol research. However, comparability of measurements conducted world-wide is hampered by lack of generally accepted technical standards and guidelines with respect to the instrumental set-up, measurement mode, data evaluation as well as quality control. Technical standards were developed for a minimum requirement of mobility size spectrometry to perform long-term atmospheric aerosol measurements. Technical recommendations include continuous monitoring of flow rates, temperature, pressure, and relative humidity for the sheath and sample air in the differential mobility analyzer.

We compared commercial and custom-made inversion routines to calculate the particle number size distributions from the measured electrical mobility distribution. All inversion routines are comparable within few per cent uncertainty for a given set of raw data.

Furthermore, this work summarizes the results from several instrument intercomparison workshops conducted within the European infrastructure project EUSAAR (European Supersites for Atmospheric Aerosol Research) and ACTRIS (Aerosols, Clouds, and Trace gases Research InfraStructure Network) to determine present uncertainties especially of custom-built mobility particle size spectrometers. Under controlled laboratory conditions, the particle number size distributions from 20 to 200 nm determined by mobility particle size spectrometers of different design are within an uncertainty range of around ±10% after correcting internal particle losses, while below and above this size range the discrepancies increased. For particles larger than 200 nm, the uncertainty range increased to 30%, which could not be explained. The network reference mobility spectrometers with identical design agreed within ±4% in the peak particle number concentration when all settings were done carefully. The consistency of these reference instruments to the total particle number concentration was demonstrated to be less than 5%.

Additionally, a new data structure for particle number size distributions was introduced to store and disseminate the data at EMEP (European Monitoring and Evaluation Program). This structure contains three levels: raw data, processed data, and final particle size distributions. Importantly, we recommend reporting raw measurements including all relevant instrument parameters as well as a complete documentation on all data transformation and correction steps. These technical and data structure standards aim to enhance the quality of long-term size distribution measurements, their comparability between different networks and sites, and their transparency and traceability back to raw data.