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Contribution of black carbon and desert dust to aerosol absorption in the atmosphere of the Eastern Arabian Peninsula

journal contribution
submitted on 2024-03-21, 08:20 and posted on 2024-03-21, 08:21 authored by Mohamed M.K. Mahfouz, Gregor Skok, Jean Sciare, Michael Pikridas, M. Rami Alfarra, Shamjad Moosakutty, Balint Alfoldy, Matic Ivančič, Martin Rigler, Asta Gregorič, Rok Podlipec, Svenja Lohmann, Gregor Hlawacek, Rene Heller, Ersin Tutsak, Griša Močnik

Discriminating the absorption coefficients of aerosol mineral dust and black carbon (BC) in different aerosol size fractions is a challenge because of BC's large mass absorption cross-section compared to dust. Ambient aerosol wavelength dependent absorption coefficients (babs) in supermicron and submicron size fractions were determined with a high time resolution. The measurements were performed simultaneously using identical systems at an urban and a regional background site in Qatar. At each site, measurements were taken by co-located Aethalometers, one with a virtual impactor (VI) and the other with a PM1 cyclone to respectively collect super-micron-enhanced and submicron fractions. The combined measurement of aerosol absorption and scattering coefficients enabled the particles to be classified based on their optical properties' wavelength dependence. The classification reveals the presence of BC internally/externally mixed with different aerosols. Helium ion microscopy images provided information concerning the extent of mineral dust in the submicron fraction. The determination of absorption coefficients during dust storms and non-dust periods was used to establish the absorption Ångström exponent for dust and BC. Non-parametric wind regression, potential source contribution function and back-trajectory analysis reveal major regional sources of desert dust associated with north-westerly winds and a minor local dust contribution. In contrast, major BC sources found locally were associated with south-westerly winds with a smaller contribution made by offshore emissions transported by north-easterly and easterly winds. The use of a pair of Aethalometers with VI and PM1 inlets separates contributions of BC and dust to the aerosol absorption coefficient.

Other Information

Published in: Atmospheric Environment
License: http://creativecommons.org/licenses/by/4.0/
See article on publisher's website: https://dx.doi.org/10.1016/j.atmosenv.2024.120427

Funding

Open Access funding provided by the Qatar National Library.

History

Language

  • English

Publisher

Elsevier

Publication Year

  • 2024

License statement

This Item is licensed under the Creative Commons Attribution 4.0 International License.

Institution affiliated with

  • Qatar University
  • Environmental Science Center - QU
  • Hamad Bin Khalifa University
  • Qatar Environment and Energy Research Institute - HBKU

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