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dc.contributor.authorPeers, F
dc.contributor.authorFrancis, P
dc.contributor.authorFox, C
dc.contributor.authorAbel, SJ
dc.contributor.authorSzpek, K
dc.contributor.authorCotterell, MI
dc.contributor.authorDavies, NW
dc.contributor.authorLangridge, JM
dc.contributor.authorMeyer, KG
dc.contributor.authorPlatnick, SE
dc.contributor.authorHaywood, JM
dc.date.accessioned2019-07-31T10:58:06Z
dc.date.issued2019-07-31
dc.description.abstractHigh-temporal-resolution observations from satellites have a great potential for studying the impact of biomass burning aerosols and clouds over the south-east Atlantic Ocean (SEAO). This paper presents a method developed to simultaneously retrieve aerosol and cloud properties in aerosol above-cloud conditions from the geostationary instrument Meteosat Second Generation/Spinning Enhanced Visible and Infrared Imager (MSG/SEVIRI). The above-cloud aerosol optical thickness (AOT), the cloud optical thickness (COT) and the cloud droplet effective radius (CER) are derived from the spectral contrast and the magnitude of the signal measured in three channels in the visible to shortwave infrared region. The impact of the absorption from atmospheric gases on the satellite signal is corrected by applying transmittances calculated using the water vapour profiles from a Met Office forecast model. The sensitivity analysis shows that a 10 % error on the humidity profile leads to an 18.5 % bias on the above-cloud AOT, which highlights the importance of an accurate atmospheric correction scheme. In situ measurements from the CLARIFY-2017 airborne field campaign are used to constrain the aerosol size distribution and refractive index that is assumed for the aforementioned retrieval algorithm. The sensitivities in the retrieved AOT, COT and CER to the aerosol model assumptions are assessed. Between 09:00 and 15:00 UTC, an uncertainty of 40 % is estimated on the above-cloud AOT, which is dominated by the sensitivity of the retrieval to the single-scattering albedo. The absorption AOT is less sensitive to the aerosol assumptions with an uncertainty generally lower than 17 % between 09:00 and 15:00 UTC. Outside of that time range, as the scattering angle decreases, the sensitivity of the AOT and the absorption AOT to the aerosol model increases. The retrieved cloud properties are only weakly sensitive to the aerosol model assumptions throughout the day, with biases lower than 6 % on the COT and 3 % on the CER. The stability of the retrieval over time is analysed. For observations outside of the backscattering glory region, the time series of the aerosol and cloud properties are physically consistent, which confirms the ability of the retrieval to monitor the temporal evolution of aerosol above-cloud events over the SEAO.en_GB
dc.description.sponsorshipResearch Council of Norwayen_GB
dc.description.sponsorshipNetBCen_GB
dc.identifier.citationVol. 19 (14), pp. 9595-9611en_GB
dc.identifier.doi10.5194/acp-19-9595-2019
dc.identifier.grantnumber240372en_GB
dc.identifier.grantnumber244141en_GB
dc.identifier.urihttp://hdl.handle.net/10871/38172
dc.language.isoenen_GB
dc.publisherEuropean Geosciences Union (EGU) / Copernicus Publicationsen_GB
dc.rights© Author(s) 2019. Open access. This work is distributed under the Creative Commons Attribution 4.0 License.en_GB
dc.titleObservation of absorbing aerosols above clouds over the south-east Atlantic Ocean from the geostationary satellite SEVIRI – Part 1: Method description and sensitivityen_GB
dc.typeArticleen_GB
dc.date.available2019-07-31T10:58:06Z
dc.identifier.issn1680-7316
dc.descriptionThis is the final version. Available on open access from EGU via the DOI in this recorden_GB
dc.descriptionData availability: The data used for this study are available from the corresponding author, FP, upon reasonable request.en_GB
dc.identifier.journalAtmospheric Chemistry and Physicsen_GB
dc.rights.urihttps://creativecommons.org/licenses/by/4.0/en_GB
dcterms.dateAccepted2019-06-19
rioxxterms.funderNatural Environment Research Councilen_GB
rioxxterms.identifier.projectNE/L013479/1en_GB
rioxxterms.versionVoRen_GB
rioxxterms.licenseref.startdate2019-07-31
rioxxterms.typeJournal Article/Reviewen_GB
refterms.dateFCD2019-07-31T10:03:27Z
refterms.versionFCDVoR
refterms.dateFOA2019-07-31T10:58:09Z
refterms.panelBen_GB
rioxxterms.funder.projecte2864054-9b0e-4fc9-8993-624c38f40ca2en_GB


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© Author(s) 2019. 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) 2019. Open access. This work is distributed under the Creative Commons Attribution 4.0 License.