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African biomass burning plumes over the Atlantic: aircraft based measurements and implications for H2SO4 and HNO3 mediated smoke particle activation

Fiedler, Verena and Arnold, Frank and Ludmann, Sabrina and Minikin, Andreas and Pirjola, L. and Dörnbrack, Andreas and Schlager, Hans (2011) African biomass burning plumes over the Atlantic: aircraft based measurements and implications for H2SO4 and HNO3 mediated smoke particle activation. Atmospheric Chemistry and Physics, 11, pp. 3211-3225. European Geosciences Union. DOI: 10.5194/acp-11-3211-2011.

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Official URL: http://www.atmos-chem-phys.net/11/3211/2011/acp-11-3211-2011.html


Airborne measurements of trace gases and aerosol particles have been made in two aged biomass burning (BB) plumes over the East Atlantic (Gulf of Guinea). The plumes originated from BB in the Southern Hemisphere African savanna belt. On the day of our measurements (13 August 2006), the plumes had ages of about 10 days and were respectively located in the middle troposphere (MT) at about 3000�5500 m altitude and in the upper troposphere (UT) at about 10 800�11 200 m. In the more polluted MT-plume, numerous measured trace species had markedly elevated abundances, particularly HNO3 (5000�8000 pmol/mol), SO2 (up to 1400 pmol/mol), and smoke particles with diameters larger than 250 nm (up to 2000 cm�3). Our MT-plume measurements indicate that SO2 released by BB had not experienced significant loss by deposition and cloud processes but rather had experienced OH-induced conversion to gas-phase sulfuric acid. By contrast, a large fraction of the released NOx had experienced loss, most likely as HNO3, by cloud processes and deposition. In the UT-plume, loss of NOy and SO2 by cloud processes and deposition was more pronounced compared to the MT-plume. Building on our measurements and accompanying model simulations, we have investigated trace gas transformations in the ageing and diluting plumes and their role in smoke particle processing and activation. Emphasis was placed upon the formation of sulfuric acid, nitric acid, and ammonium nitrate, and their influence on the activation potential of smoke particles. Our model simulations reveal that, after 13 August, the lower plume traveled across the Atlantic and descended to 1300 m and hereafter ascended again. During the travel across the Atlantic, the smoke particle mean diameter and sulfuric acid mass fraction increased sufficiently to allow the processed smoke particles to act as water vapor condensation nuclei already at very low water vapor supersaturations of only about 0.04%. Thereby, aged smoke particles had developed a potential to act as water vapor condensation nuclei in the formation of maritime clouds, including not only cumulus but even stratiform clouds.

Document Type:Article
Title:African biomass burning plumes over the Atlantic: aircraft based measurements and implications for H2SO4 and HNO3 mediated smoke particle activation
AuthorsInstitution or Email of Authors
Fiedler, VerenaDLR
Arnold, FrankMPIK, Heidelberg
Ludmann, SabrinaMPIK, Heidelberg
Minikin, AndreasDLR
Pirjola, L.Univ. of Helsinki, Helsinki, FIN
Dörnbrack, AndreasDLR
Schlager, HansDLR
Journal or Publication Title:Atmospheric Chemistry and Physics
Refereed publication:Yes
In Open Access:Yes
In ISI Web of Science:Yes
Page Range:pp. 3211-3225
Publisher:European Geosciences Union
Keywords:AMMA, biomass burning, particle activation, Falcon
HGF - Research field:Aeronautics, Space and Transport (old)
HGF - Program:Space (old)
HGF - Program Themes:W EO - Erdbeobachtung
DLR - Research area:Space
DLR - Program:W EO - Erdbeobachtung
DLR - Research theme (Project):W - Vorhaben Atmosphären- und Klimaforschung (old)
Location: Oberpfaffenhofen
Institutes and Institutions:Institute of Atmospheric Physics > Atmospheric Trace Species
Deposited By: Dr.rer.nat. Andreas Minikin
Deposited On:08 Dec 2010 15:52
Last Modified:12 Dec 2013 21:08

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