Light extinction by secondary organic aerosol: an intercomparison of three broadband cavity spectrometers

Show simple item record Varma, Ravi M. Ball, Stephen M. Brauers, T. Dorn, H. P. Heitmann, Uwe M. Jones, R. L. Platt, U. Pöhler, D. Ruth, Albert A. Shillings, A. J. L. Thieser, J. Wahner, A. Venables, Dean S. 2013-12-05T17:17:14Z 2013-12-05T17:17:14Z 2013
dc.identifier.citation Varma, R. M., Ball, S. M., Brauers, T., Dorn, H.-P., Heitmann, U., Jones, R. L., Platt, U., Pöhler, D., Ruth, A. A., Shillings, A. J. L., Thieser, J., Wahner, A., and Venables, D. S.: Light extinction by Secondary Organic Aerosol: an intercomparison of three broadband cavity spectrometers, Atmos. Meas. Tech. Discuss., 6, 6685-6727, doi:10.5194/amtd-6-6685-2013, 2013. en
dc.identifier.volume 6 en
dc.identifier.startpage 6685 en
dc.identifier.endpage 6727 en
dc.identifier.doi 10.5194/amtd-6-6685-2013
dc.description.abstract Broadband optical cavity spectrometers are maturing as a technology for trace gas detection, but only recently have they been used to retrieve the extinction coefficient of aerosols. Sensitive broadband extinction measurements allow explicit separation of gas and particle phase spectral contributions, as well as continuous spectral measurements of aerosol extinction in favourable cases. In this work, we report an intercomparison study of the aerosol extinction coefficients measured by three such instruments: a broadband cavity ring-down spectrometer (BBCRDS), a cavity-enhanced differential optical absorption spectrometer (CE-DOAS), and an incoherent broadband cavity-enhanced absorption spectrometer (IBBCEAS). Experiments were carried out in the SAPHIR atmospheric simulation chamber as part of the NO3Comp campaign to compare the measurement capabilities of NO3 and N2O5 instrumentation. Aerosol extinction coefficients between 655 and 690 nm are reported for secondary organic aerosols (SOA) formed by the NO3 oxidation of β-pinene under dry and humid conditions. Despite different measurement approaches and spectral analysis procedures, the three instruments retrieved aerosol extinction coefficients that were in close agreement. The refractive index of SOA formed from the β-pinene + NO3 reaction was 1.61, and was not measurably affected by the chamber humidity or by aging of the aerosol over several hours. This refractive index is significantly larger than SOA refractive indices observed in other studies of OH and ozone-initiated terpene oxidations, and may be caused by the large proportion of organic nitrates in the particle phase. In an experiment involving ammonium sulphate particles the aerosol extinction coefficients as measured by IBBCEAS were found to be in reasonable agreement with those calculated using Mie theory. The results of the study demonstrate the potential of broadband cavity spectrometers for determining the optical properties of aerosols. en
dc.description.sponsorship Environmental Protection Agency (2005-ET-MS-28-M3); Science Foundation Ireland (11/RFP/GEO3200, and 06/RFP/CHP055-STTF09); Natural Environment Research Council (NER/T/S/2002/00036); European Commission (FP6 - RII3-CT-2004-505968) en
dc.format.mimetype application/pdf en
dc.language.iso en en
dc.publisher Copernicus Publications en
dc.rights © Author(s) 2013. This work is distributed under the Creative Commons Attribution 3.0 License. en
dc.subject Aerosol extinction measurement en
dc.subject Broadband optical cavity spectrometers en
dc.subject CEAS en
dc.title Light extinction by secondary organic aerosol: an intercomparison of three broadband cavity spectrometers en
dc.type Article (non peer-reviewed) en
dc.internal.authorcontactother Dean Venables, Chemistry, University College Cork, Cork, Ireland. +353-21-490-3000 Email: en
dc.internal.availability Full text available en 2013-08-15T11:52:34Z
dc.description.version Published Version en
dc.internal.rssid 225804362
dc.contributor.funder Environmental Protection Agency en
dc.contributor.funder Science Foundation Ireland en
dc.description.status Not peer reviewed en
dc.identifier.journaltitle Atmospheric Measurement Techniques Discussions en
dc.internal.copyrightchecked No I expect there is no problem with Copernicus publications which follow an author pays model and are freely available online at the publisher's site. en
dc.internal.licenseacceptance Yes en
dc.internal.IRISemailaddress en

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