Remote sensing of soot carbon - Part 1: Distinguishing different absorbing aerosol species
International audience We describe a method of using the Aerosol Robotic Network (AERONET) size distributions and complex refractive indices to retrieve the relative proportion of carbonaceous aerosols and free iron minerals (hematite and goethite). We assume that soot carbon has a spectrally flat r...
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ftinsu:oai:HAL:insu-03686216v1 2024-02-11T09:54:46+01:00 Remote sensing of soot carbon - Part 1: Distinguishing different absorbing aerosol species Schuster, G. L. Dubovik, O. Arola, A. Laboratoire d’Optique Atmosphérique - UMR 8518 (LOA) Institut national des sciences de l'Univers (INSU - CNRS)-Université de Lille-Centre National de la Recherche Scientifique (CNRS) ANR-11-LABX-0005,Cappa,Physiques et Chimie de l'Environnement Atmosphérique(2011) 2016 https://insu.hal.science/insu-03686216 https://insu.hal.science/insu-03686216/document https://insu.hal.science/insu-03686216/file/acp-16-1565-2016.pdf https://doi.org/10.5194/acp-16-1565-2016 en eng HAL CCSD European Geosciences Union info:eu-repo/semantics/altIdentifier/doi/10.5194/acp-16-1565-2016 insu-03686216 https://insu.hal.science/insu-03686216 https://insu.hal.science/insu-03686216/document https://insu.hal.science/insu-03686216/file/acp-16-1565-2016.pdf BIBCODE: 2016ACP.16.1565S doi:10.5194/acp-16-1565-2016 http://creativecommons.org/licenses/by/ info:eu-repo/semantics/OpenAccess ISSN: 1680-7316 EISSN: 1680-7324 Atmospheric Chemistry and Physics https://insu.hal.science/insu-03686216 Atmospheric Chemistry and Physics, 2016, 16, pp.1565-1585. ⟨10.5194/acp-16-1565-2016⟩ [SDU]Sciences of the Universe [physics] info:eu-repo/semantics/article Journal articles 2016 ftinsu https://doi.org/10.5194/acp-16-1565-2016 2024-01-24T17:29:29Z International audience We describe a method of using the Aerosol Robotic Network (AERONET) size distributions and complex refractive indices to retrieve the relative proportion of carbonaceous aerosols and free iron minerals (hematite and goethite). We assume that soot carbon has a spectrally flat refractive index and enhanced imaginary indices at the 440 nm wavelength are caused by brown carbon or hematite. Carbonaceous aerosols can be separated from dust in imaginary refractive index space because 95 % of biomass burning aerosols have imaginary indices greater than 0.0042 at the 675-1020 nm wavelengths, and 95 % of dust has imaginary refractive indices of less than 0.0042 at those wavelengths. However, mixtures of these two types of particles can not be unambiguously partitioned on the basis of optical properties alone, so we also separate these particles by size. Regional and seasonal results are consistent with expectations. Monthly climatologies of fine mode soot carbon are less than 1.0 % by volume for West Africa and the Middle East, but the southern African and South American biomass burning sites have peak values of 3.0 and 1.7 %. Monthly averaged fine mode brown carbon volume fractions have a peak value of 5.8 % for West Africa, 2.1 % for the Middle East, 3.7 % for southern Africa, and 5.7 % for South America. Monthly climatologies of free iron volume fractions show little seasonal variability, and range from about 1.1 to 1.7 % for coarse mode aerosols in all four study regions. Finally, our sensitivity study indicates that the soot carbon retrieval is not sensitive to the component refractive indices or densities assumed for carbonaceous and free iron aerosols, and the retrieval differs by only 15.4 % when these parameters are altered from our chosen baseline values. The total uncertainty of retrieving soot carbon mass is ∼ 50 % (when uncertainty in the AERONET product and mixing state is included in the analysis). Article in Journal/Newspaper Aerosol Robotic Network Institut national des sciences de l'Univers: HAL-INSU Atmospheric Chemistry and Physics 16 3 1565 1585 |
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Institut national des sciences de l'Univers: HAL-INSU |
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English |
topic |
[SDU]Sciences of the Universe [physics] |
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[SDU]Sciences of the Universe [physics] Schuster, G. L. Dubovik, O. Arola, A. Remote sensing of soot carbon - Part 1: Distinguishing different absorbing aerosol species |
topic_facet |
[SDU]Sciences of the Universe [physics] |
description |
International audience We describe a method of using the Aerosol Robotic Network (AERONET) size distributions and complex refractive indices to retrieve the relative proportion of carbonaceous aerosols and free iron minerals (hematite and goethite). We assume that soot carbon has a spectrally flat refractive index and enhanced imaginary indices at the 440 nm wavelength are caused by brown carbon or hematite. Carbonaceous aerosols can be separated from dust in imaginary refractive index space because 95 % of biomass burning aerosols have imaginary indices greater than 0.0042 at the 675-1020 nm wavelengths, and 95 % of dust has imaginary refractive indices of less than 0.0042 at those wavelengths. However, mixtures of these two types of particles can not be unambiguously partitioned on the basis of optical properties alone, so we also separate these particles by size. Regional and seasonal results are consistent with expectations. Monthly climatologies of fine mode soot carbon are less than 1.0 % by volume for West Africa and the Middle East, but the southern African and South American biomass burning sites have peak values of 3.0 and 1.7 %. Monthly averaged fine mode brown carbon volume fractions have a peak value of 5.8 % for West Africa, 2.1 % for the Middle East, 3.7 % for southern Africa, and 5.7 % for South America. Monthly climatologies of free iron volume fractions show little seasonal variability, and range from about 1.1 to 1.7 % for coarse mode aerosols in all four study regions. Finally, our sensitivity study indicates that the soot carbon retrieval is not sensitive to the component refractive indices or densities assumed for carbonaceous and free iron aerosols, and the retrieval differs by only 15.4 % when these parameters are altered from our chosen baseline values. The total uncertainty of retrieving soot carbon mass is ∼ 50 % (when uncertainty in the AERONET product and mixing state is included in the analysis). |
author2 |
Laboratoire d’Optique Atmosphérique - UMR 8518 (LOA) Institut national des sciences de l'Univers (INSU - CNRS)-Université de Lille-Centre National de la Recherche Scientifique (CNRS) ANR-11-LABX-0005,Cappa,Physiques et Chimie de l'Environnement Atmosphérique(2011) |
format |
Article in Journal/Newspaper |
author |
Schuster, G. L. Dubovik, O. Arola, A. |
author_facet |
Schuster, G. L. Dubovik, O. Arola, A. |
author_sort |
Schuster, G. L. |
title |
Remote sensing of soot carbon - Part 1: Distinguishing different absorbing aerosol species |
title_short |
Remote sensing of soot carbon - Part 1: Distinguishing different absorbing aerosol species |
title_full |
Remote sensing of soot carbon - Part 1: Distinguishing different absorbing aerosol species |
title_fullStr |
Remote sensing of soot carbon - Part 1: Distinguishing different absorbing aerosol species |
title_full_unstemmed |
Remote sensing of soot carbon - Part 1: Distinguishing different absorbing aerosol species |
title_sort |
remote sensing of soot carbon - part 1: distinguishing different absorbing aerosol species |
publisher |
HAL CCSD |
publishDate |
2016 |
url |
https://insu.hal.science/insu-03686216 https://insu.hal.science/insu-03686216/document https://insu.hal.science/insu-03686216/file/acp-16-1565-2016.pdf https://doi.org/10.5194/acp-16-1565-2016 |
genre |
Aerosol Robotic Network |
genre_facet |
Aerosol Robotic Network |
op_source |
ISSN: 1680-7316 EISSN: 1680-7324 Atmospheric Chemistry and Physics https://insu.hal.science/insu-03686216 Atmospheric Chemistry and Physics, 2016, 16, pp.1565-1585. ⟨10.5194/acp-16-1565-2016⟩ |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.5194/acp-16-1565-2016 insu-03686216 https://insu.hal.science/insu-03686216 https://insu.hal.science/insu-03686216/document https://insu.hal.science/insu-03686216/file/acp-16-1565-2016.pdf BIBCODE: 2016ACP.16.1565S doi:10.5194/acp-16-1565-2016 |
op_rights |
http://creativecommons.org/licenses/by/ info:eu-repo/semantics/OpenAccess |
op_doi |
https://doi.org/10.5194/acp-16-1565-2016 |
container_title |
Atmospheric Chemistry and Physics |
container_volume |
16 |
container_issue |
3 |
container_start_page |
1565 |
op_container_end_page |
1585 |
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1790603598753693696 |