1. Aethalometer multiple scattering correction Cref for mineral dust aerosols
- Author
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Di Biagio , Claudia, Formenti , Paola, Cazaunau , Mathieu, Pangui , Edouard, Marchand , Nicolas, Doussin , Jean-Francois, Laboratoire inter-universitaire des systèmes atmosphèriques ( LISA ), Institut national des sciences de l'Univers ( INSU - CNRS ) -Université Paris Diderot - Paris 7 ( UPD7 ) -Université Paris-Est Créteil Val-de-Marne - Paris 12 ( UPEC UP12 ) -Centre National de la Recherche Scientifique ( CNRS ), Centre National de la Recherche Scientifique ( CNRS ), Laboratoire de Physico -& Toxico Chimie des systèmes naturels ( LPTC ), Université Sciences et Technologies - Bordeaux 1-Centre National de la Recherche Scientifique ( CNRS ), Laboratoire Chimie de l'environnement ( LCE ), Aix Marseille Université ( AMU ) -Centre National de la Recherche Scientifique ( CNRS ), Laboratoire inter-universitaire des systèmes atmosphèriques (LISA), Institut national des sciences de l'Univers (INSU - CNRS) - Université Paris Diderot - Paris 7 (UPD7) - Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12) - Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physico -& Toxico Chimie des systèmes naturels (LPTC), Université Sciences et Technologies - Bordeaux 1 - Centre National de la Recherche Scientifique (CNRS), Laboratoire Chimie de l'environnement (LCE), Centre National de la Recherche Scientifique (CNRS) - Aix Marseille Université (AMU), Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA (UMR_7583)), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1 (UB)-Centre National de la Recherche Scientifique (CNRS), Aix Marseille Université (AMU)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1-Centre National de la Recherche Scientifique (CNRS), and Centre National de la Recherche Scientifique (CNRS)-Aix Marseille Université (AMU)
- Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere ,[ SDU.OCEAN ] Sciences of the Universe [physics]/Ocean, Atmosphere ,lcsh:TA715-787 ,[SDE.IE]Environmental Sciences/Environmental Engineering ,[SDU.OCEAN] Sciences of the Universe [physics]/Ocean, Atmosphere ,[SDE.MCG]Environmental Sciences/Global Changes ,lcsh:Earthwork. Foundations ,TA715-787 ,Environmental engineering ,TA170-171 ,[ SDE.IE ] Environmental Sciences/Environmental Engineering ,lcsh:Environmental engineering ,[SDE.MCG] Environmental Sciences/Global Changes ,[ SDE.MCG ] Environmental Sciences/Global Changes ,Earthwork. Foundations ,[CHIM.OTHE] Chemical Sciences/Other ,[ CHIM.OTHE ] Chemical Sciences/Other ,[SDE.IE] Environmental Sciences/Environmental Engineering ,lcsh:TA170-171 ,[CHIM.OTHE]Chemical Sciences/Other - Abstract
In this study we provide a first estimate of the Aethalometer multiple scattering correction Cref for mineral dust aerosols. Cref is an empirical constant used to correct the aerosol absorption coefficient measurements for the multiple scattering artefact of the Aethalometer; i.e. the filter fibres on which aerosols are deposited scatter light and this is miscounted as absorption. The Cref at 450 and 660 nm was obtained from the direct comparison of Aethalometer data (Magee Sci. AE31) with (i) the absorption coefficient calculated as the difference between the extinction and scattering coefficients measured by a Cavity Attenuated Phase Shift Extinction analyser (CAPS PMex) and a nephelometer respectively at 450 nm and (ii) the absorption coefficient from a MAAP (Multi-Angle Absorption Photometer) at 660 nm. Measurements were performed on seven dust aerosol samples generated in the laboratory by the mechanical shaking of natural parent soils issued from different source regions worldwide. The single scattering albedo (SSA) at 450 and 660 nm and the size distribution of the aerosols were also measured. Cref for mineral dust varies between 1.81 and 2.56 for a SSA of 0.85–0.96 at 450 nm and between 1.75 and 2.28 for a SSA of 0.98–0.99 at 660 nm. The calculated mean for dust is 2.09 (±0.22) at 450 nm and 1.92 (±0.17) at 660 nm. With this new Cref the dust absorption coefficient by the Aethalometer is about 2 % (450 nm) and 11 % (660 nm) higher than that obtained by using Cref = 2.14 at both 450 and 660 nm, as usually assumed in the literature. This difference induces a change of up to 3 % in the dust SSA at 660 nm. The Cref seems to be independent of the fine and coarse particle size fractions, and so the obtained Cref can be applied to dust both close to sources and following transport. Additional experiments performed with pure kaolinite minerals and polluted ambient aerosols indicate Cref of 2.49 (±0.02) and 2.32 (±0.01) at 450 and 660 nm (SSA = 0.96–0.97) for kaolinite, and Cref of 2.32 (±0.36) at 450 nm and 2.32 (±0.35) at 660 nm for pollution aerosols (SSA = 0.62–0.87 at 450 nm and 0.42–0.76 at 660 nm).
- Published
- 2017