Format:
Online-Ressource
ISSN:
1680-7324
Content:
Abstract 530 nm 〉 0.975 point indirectly to the dry, flame-efficient combustion of primarily grass fuels, with back trajectories ending in the miombo woodlands of Angola. The youngest aerosol, aged 4–5 d since emission, occupied the top half of a 5 km thick plume sampled directly west of Angola with a vertically consistent BC: Δ CO (carbon monoxide) ratio, indicating a homogenization of the source emissions. The younger aerosol, transported more quickly off of the continent by stronger winds, overlaid older, slower-moving aerosol with a larger mean particle size and fraction of BC-containing particles. This is consistent with ongoing gas condensation and the coagulation of smaller non-BC particles upon the BC-containing particles. The particle volumes and OA: BC mass ratios of the older aerosol were smaller, attributed primarily to evaporation following fragmentation, instead of dilution or thermodynamics. The CLARIFY (CLoud–Aerosol–Radiation Interaction and Forcing: Year 2017) aircraft campaign sampled aerosols that had traveled further to reach the more remote Ascension Island. CLARIFY reported higher BC number fractions, lower OA: BC mass ratios, and lower SSA yet larger mass absorption coefficients compared to this study's. Values from one ORACLES 2017 flight, held midway to Ascension Island, are intermediate, confirming the long-range changes. Overall the data are most consistent with continuing oxidation through fragmentation releasing aerosols that subsequently enter the gas phase, reducing the OA mass, rather than evaporation through dilution or thermodynamics. The data support the following best fit: SSA530 nm = 0.801 + 0055 ⋅ (OA: BC) (r = 0.84). The fires of southern Africa emit approximately one-third of the world's carbon; the emitted aerosols are distinct from other regional smoke emissions, and their composition needs to be represented appropriately to realistically depict regional aerosol radiative effects.
In:
volume:23
In:
number:8
In:
year:2023
In:
pages:4775-4799
In:
extent:25
In:
Atmospheric chemistry and physics, Katlenburg-Lindau : EGU, 2001-, 23, Heft 8 (2023), 4775-4799 (gesamt 25), 1680-7324
Language:
English
DOI:
10.5194/acp-23-4775-2023
URN:
urn:nbn:de:101:1-2023042708055644813875
URL:
https://doi.org/10.5194/acp-23-4775-2023
URL:
https://nbn-resolving.org/urn:nbn:de:101:1-2023042708055644813875
URL:
https://d-nb.info/1287147852/34
URL:
https://acp.copernicus.org/articles/23/4775/2023/acp-23-4775-2023.pdf
URL:
https://acp.copernicus.org/articles/23/4775/2023/
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