HR: 14:25h
AN: A42E-04    [PDF]
TI: Amplification of Black Carbon Absorption by Internal Mixing With Secondary Organic Aerosol Mass
AU: * Schnaiter, M
EM: martin.schnaiter@imk.fzk.de
AF: Forschungszentrum Karlsruhe, IMK-AAF, P.O. Box 3640, Karlsruhe, 76021 Germany
AU: Linke, C
AF: Forschungszentrum Karlsruhe, IMK-AAF, P.O. Box 3640, Karlsruhe, 76021 Germany
AU: M\"ohler, O
AF: Forschungszentrum Karlsruhe, IMK-AAF, P.O. Box 3640, Karlsruhe, 76021 Germany
AU: Naumann, K
AF: Forschungszentrum Karlsruhe, IMK-AAF, P.O. Box 3640, Karlsruhe, 76021 Germany
AU: Saathoff, H
AF: Forschungszentrum Karlsruhe, IMK-AAF, P.O. Box 3640, Karlsruhe, 76021 Germany
AU: Sch\"ock, W
AF: Forschungszentrum Karlsruhe, IMK-AAF, P.O. Box 3640, Karlsruhe, 76021 Germany
AU: Wagner, R
AF: Forschungszentrum Karlsruhe, IMK-AAF, P.O. Box 3640, Karlsruhe, 76021 Germany
AU: Wehner, B
AF: Leibniz-Institut f\"ur Troposph\"arenforschung, Permoserstrasse 15, Leipzig, 04318 Germany
AU: Schurath, U
AF: Forschungszentrum Karlsruhe, IMK-AAF, P.O. Box 3640, Karlsruhe, 76021 Germany
AB: Atmospheric soot or black carbon (BC) might have a significant warming influence on local and global climate. During its residence time within the atmosphere freshly emitted BC is aged by microphysical processes like coagulation, the condensation of low and semi-volatile gaseous compounds, and cloud cycling. Especially the latter two processes dominate the atmospheric ageing and result in an internal mixture by the inclusion of BC in transparent host particles composed of organic or inorganic material. It is well known from several theoretical investigations that internally mixed BC has an amplified mass specific absorption cross section. When accounting for the internal aerosol mixing in global circulation models a doubling of the climate warming potential of BC was found compared to the external case. However, these studies use relatively simple particle models to calculate the optics of the aerosol particles. Since the overall diversity and complexity of the atmospheric aerosol morphology could not be accounted for in optical models, lab investigations which simulate the atmospheric BC ageing processes under realistic conditions are desirable to get a more reliable assessment of the direct climate forcing by anthropogenic BC emissions. The large aerosol chamber AIDA of Forschungszentrum Karlsruhe is well suited to simulate atmospheric aerosol aging processes over a wide range of temperature and pressure conditions. The absorption and scattering properties of BC internally mixed with SOA mass were investigated at the AIDA facility. BC particles were coated in situ by secondary organic material generated by the ozonolysis of $\alpha$-pinene. A significant increase of the specific BC absorption cross section in the visible by a factor of more than 1.8 can be inferred from the experiments. The measured optical properties are compared with theoretical investigations using a concentric core shell model to calculate the optical properties of the internally mixed BC aerosol.
UR: http://www.aerosoloptics.de
DE: 0305 Aerosols and particles (0345, 4801)
DE: 0360 Transmission and scattering of radiation
DE: 0365 Troposphere--composition and chemistry
DE: 0394 Instruments and techniques
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting