The role of blank filter mass in attenuation measurements using an off-line transmissometer

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• dc.contributor.author Sreekanth, Vakacherla
• dc.contributor.author Tonne, Cathryn
• dc.contributor.author Salmon, Maëlle
• dc.contributor.author Arulselvan, S.
• dc.contributor.author Marshall, Julian D.
• dc.date.accessioned 2019-09-12T16:57:16Z
• dc.date.issued 2019
• dc.description.abstract We describe how reference filter characteristics (unexposed weights) can influence instrument-reported attenuation (thereby black carbon concentrations) using the OT21 (SootScan Optical Transmissometer), in the case of Emfab filters. Reference filters (unexposed filters) with higher unexposed weights (pre-weights) compared to that of sample filters are found to reduce the instrument-reported aerosol sample attenuation measurement; reference filters weighing less than the sample filter results in the reverse outcome. This sensitivity can lead to significant under- and over-estimation by the instrument (estimated mean absolute error: ∼ 10 and 16 ATN units for infrared (IR) and ultraviolet (UV) channels, respectively, in our tests, which represent 44% and 15% errors, respectively). We find that the error is linear with respect to difference in the unexposed filter weights of the sample and reference filters. We report two equations (one for IR, one for UV) for correcting the Transmissometer output based on experimental data, which allow use of any unexposed Emfab filter as the reference filter; application of correction parameters to data here reduces the error to 2 and 3 ATN units, respectively, for IR and UV (10% and 3% errors, respectively).
• dc.description.sponsorship The research leading to these results received funding from the European Research Council under ERC Grant Agreement number 336167 for the CHAI Project. We are thankful to field staff of CHAI project and Sri Ramachandra University, Chennai for their collaboration throughout the monitoring and measurements. Filter weight data is available from the corresponding author on request.
• dc.format.mimetype application/pdf
• dc.identifier.citation Sreekanth V, Tonne C, Salmon M, Arulselvan S, Marshall JD. The role of blank filter mass in attenuation measurements using an off-line transmissometer. J Aerosol Sci. 2019; 131:41-47. DOI: 10.1016/j.jaerosci.2019.03.001
• dc.identifier.doi http://dx.doi.org/10.1016/j.jaerosci.2019.03.001
• dc.identifier.issn 0021-8502
• dc.identifier.uri http://hdl.handle.net/10230/42270
• dc.language.iso eng
• dc.publisher Elsevier
• dc.relation.ispartof J Aerosol Sci. 2019; 131:41-47
• dc.relation.projectID info:eu-repo/grantAgreement/EC/FP7/336167
• dc.rights © Elsevier http://dx.doi.org/10.1016/j.jaerosci.2019.03.001
• dc.rights.accessRights info:eu-repo/semantics/openAccess
• dc.subject.keyword Emfab
• dc.subject.keyword Filter thickness
• dc.subject.keyword Transmittance
• dc.subject.keyword Light attenuation
• dc.title The role of blank filter mass in attenuation measurements using an off-line transmissometer
• dc.type info:eu-repo/semantics/article
• dc.type.version info:eu-repo/semantics/acceptedVersion