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dc.contributor.authorMorgan, WT
dc.contributor.authorAllan, JD
dc.contributor.authorBauguitte, S
dc.contributor.authorDarbyshire, E
dc.contributor.authorFlynn, MJ
dc.contributor.authorLee, J
dc.contributor.authorLiu, D
dc.contributor.authorJohnson, B
dc.contributor.authorHaywood, J
dc.contributor.authorLongo, KM
dc.contributor.authorArtaxo, PE
dc.contributor.authorCoe, H
dc.date.accessioned2020-05-06T15:40:21Z
dc.date.issued2020-05-06
dc.description.abstractWe present a range of airborne in situ observations of biomass burning carbonaceous aerosol over tropical South America, including a case study of a large tropical forest wildfire and a series of regional survey flights across the Brazilian Amazon and Cerrado. The study forms part of the South American Biomass Burning Analysis (SAMBBA) project, which was conducted during September and October 2012. We find limited evidence for net increases in aerosol mass through atmospheric ageing combined with substantial changes in the chemical properties of organic aerosol (OA). Oxidation of the OA increases significantly and rapidly on the scale of 2.5–3 h based on our case study analysis and is consistent with secondary organic aerosol production. The observations of limited net enhancement in OA coupled with such changes in chemical composition imply that evaporation of OA is also occurring to balance these changes. We observe significant coatings on black carbon particles at source, but with limited changes with ageing in both particle core size and coating thickness. We quantify variability in the ratio of OA to carbon monoxide across our study as a key parameter representing both initial fire conditions and an indicator of net aerosol production with atmospheric ageing. We observe ratios of 0.075–0.13 µgsm−3ppbv−1 in the west of our study region over the Amazon tropical forest in air masses less influenced by precipitation and a value of 0.095 µgsm−3ppbv−1 over the Cerrado environment in the east (where sm−3 refers to standard metre cubed). Such values are consistent with emission factors used by numerical models to represent biomass burning OA emissions. Black carbon particle core sizes typically range from mean mass diameters of 250 to 290 nm, while coating thicknesses range from 40 to 110 nm in air masses less influenced by precipitation. The primary driver of the variability we observe appears to be related to changes at the initial fire source. A key lesson from our study is that simply aggregating our observations as a function of atmospheric ageing would have been misleading due to the complex nature of the regional aerosol and its drivers, due to the many conflating and competing factors that are present. Our study explores and quantifies key uncertainties in the evolution of biomass burning aerosol at both near-field and regional scales. Our results suggest that the initial conditions of the fire are the primary driver of carbonaceous aerosol physical and chemical properties over tropical South America, aside from significant oxidation of OA during atmospheric ageing. Such findings imply that uncertainties in the magnitude of the aerosol burden and its impact on weather, climate, health and natural ecosystems most likely lie in quantifying emission sources, alongside atmospheric dispersion, transport and removal rather than chemical enhancements in mass.en_GB
dc.description.sponsorshipNatural Environment Research Council (NERC)en_GB
dc.description.sponsorshipFAPESP (Fundação de Amparo à Pesquisa do Estado de São Pauloen_GB
dc.identifier.citationVol. 20, pp. 5309 - 5326en_GB
dc.identifier.doi10.5194/acp-20-5309-2020
dc.identifier.grantnumberNE/J500057/1en_GB
dc.identifier.grantnumberNE/K500859/1en_GB
dc.identifier.grantnumberNE/J010073/1en_GB
dc.identifier.grantnumber2017-17047-0en_GB
dc.identifier.grantnumberINCT 2014/50848-9en_GB
dc.identifier.urihttp://hdl.handle.net/10871/120961
dc.language.isoenen_GB
dc.publisherEuropean Geosciences Union (EGU) / Copernicus Publicationsen_GB
dc.rights© Author(s) 2020. Open access. This work is distributed under the Creative Commons Attribution 4.0 License.en_GB
dc.titleTransformation and ageing of biomass burning carbonaceous aerosol over tropical South America from aircraft in situ measurements during SAMBBAen_GB
dc.typeArticleen_GB
dc.date.available2020-05-06T15:40:21Z
dc.descriptionThis is the final version. Available on open access from the European Geosciences Union via the DOI in this recorden_GB
dc.descriptionData availability. All raw time series data from the FAAM research aircraft are publicly available from the Centre for Environmental Data Analysis (http://www.ceda.ac.uk/, last access: July 2014), where the entire SAMBBA dataset may be accessed at https://catalogue.ceda.ac.uk/uuid/2ff89840a89840868acff801f8859451 (SAMBBA, 2014). AMS mass spectral features, SP2 size distribution and coating thickness data are available on request. Data masks for categorising flight patterns into plume-sampling and other sampling types (vertical profiles and SLRs) are currently available on request. Active fire data used in the paper are available publicly from NASA (see acknowledgements for further details).en_GB
dc.identifier.eissn1680-7324
dc.identifier.journalAtmospheric Chemistry and Physicsen_GB
dc.rights.urihttps://creativecommons.org/licenses/by/4.0/en_GB
dcterms.dateAccepted2020-03-15
rioxxterms.versionVoRen_GB
rioxxterms.licenseref.startdate2020-05-06
rioxxterms.typeJournal Article/Reviewen_GB
refterms.dateFCD2020-05-06T15:37:15Z
refterms.versionFCDVoR
refterms.dateFOA2020-05-06T15:40:25Z
refterms.panelBen_GB


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© Author(s) 2020. Open access. This work is distributed under
the Creative Commons Attribution 4.0 License.
Except where otherwise noted, this item's licence is described as © Author(s) 2020. Open access. This work is distributed under the Creative Commons Attribution 4.0 License.