Recommendations for the Interpretation of "Black Carbon" Measurements

1. Recommendations for the Interpretation of "Black Carbon" Measurements A. Petzold1, J. A. Ogren2, M. Fiebig3, P. Laj4, S.-M. Li5, U. Baltensperger6, Th. Holzer-Popp7, S. Kinne8, G. Pappalardo9, N. Sugimoto10, C. Wehrli11, A. Wiedensohler12, and X.-Y. Zhang13 What is Black Carbon • Black carbon (BC) is carbon that is black • The formation process is excluded from this definition because of the variety of potential processes. While BC is mostly formed in incomplete combustion, it can be a pro-duct of pyrolysis of carbonaceous matter, dehydration of sugar, or heating of wood in an oxygen-free atmosphere • Elemental carbon (EC) is formally defined as a substance containing only carbon • The formal term “elemental carbon” refers to a set of materials with different optical and physical properties instead of a given material with well-defined properties. Examples of “true” EC are diamond, carbon nanotubes, graphite or fullerenes. • Strict definitions are not particularly useful in practicebecause • carbonaceous matter appears in atmospheric aerosols under no circumstances as pure matter; • it occurs as a highly variable mixture of different carbonaceous compounds with different material properties. Interpreting “BC” Measurements Classification and molecular structure of carbonaceous aerosol components (Pöschl, Anal Bioanal Chem 2003) Delhaye, 2009 Structure of Black Carbon in the atmosphere (Ogren & Charlson TELLUS 1983) “Black Carbon” Measurement Methods Properties defining Black Carbon and their consequences for effects and atmospheric lifetime • Evolved Carbon • CO2evolved from thermal or thermo - optical methods; applied analytical protocols, e.g. IMPROVE / EUSAAR • BC properties: chemical composition, thermal stability • Light Absorption • Filter-based: Aethalometer, PSAP, MAAP, COSMOS • In situ: photo-acoustic, ext. minus scat. • BC properties: light absorption • Laser Incandescence • Laser heating of particles, e.g., SP2, LII • BC Properties: refractory, chemical composition Aerosol Mass Spectrometry • Vaporization and detection of carbon ion clusters in mass spectra: ATOFMS, SP-AMS • BC properties: chemical composition Raman Spectrometry • Detection of graphite-like ordered and disordered carbon • BC properties: graphite-like microstructure Electron microscopy • Detection of particle microstructure and morphology, e.g. TEM • BC properties: morphology Recommended Terminology GAW Scientific Advisory Group Aerosol SAG website: http://gaw.tropos.de Chairman: J. A. Ogren , NOAA john.a.ogren@noaa.gov These recommendations are a result of discussions carried out in the context of the Scientific Advisory Group (SAG) for Aerosols of the Global Atmosphere Watch (GAW) program of the World Meteorological Organization (WMO). However, the authors express their own views and do not act on behalf of, or commit, their institutions, ministries or WMO. Affiliations of GAW SAG Aerosol Members 1 Forschungszentrum Jülich GmbH, Institut für Energie- und Klimaforschung IEK-8, 52425 Jülich, Germany 2 NOAA/ESRL Global Monitoring Division, Boulder, CO 80305, USA 3 Norwegian Institute for Air Research (NILU), N-2027 Kjeller, Norway 4 Laboratoire de Glaciologie et Géophysique de l'Environnement, Université de Grenoble I - CNRS, 38402 - Saint Martin d'Hères cedex, France 5 Environment Canada, Processes Research Section, Toronto, ON M3H 5T4, Canada 6 Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland 7 Deutsches Fernerkundungsdatenzentrum, DLR, 82234 Oberpfaffenhofen, Germany 8 Max Planck Institute for Meteorology, Bundesstrasse 53, 20146 Hamburg, Germany 9 Istituto di Metodologie per l'Analisi Ambientale (CNR-IMAA), Potenza, I-85050, Italy 10 National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan 11 Physikalisch-Meteorologisches Observatorium Davos (PMOD/WRC), 7260 Davos, Switzerland 12 Leibniz Institute for Tropospheric Research, Permoserstr. 15, 04318 Leipzig, Germany 13 Chinese Academy of Meteorological Sciences, 46 Zhong-Guan-Cun S. Av., Beijing 100081, China Photo by courtesy of Alexander Karmazin Contact: Andreas Petzold, Institut für Energie- und Klimaforschung IEK-8: Troposphäre, FZ Jülich a.petzold@fz-juelich.de