Atmospheric processing and aerosol aging responsible for observed increase in absorptivity of long-range-transported smoke over the southeast Atlantic

Abdulamid Fakoya; Jens Redemann; Pablo Saide; Lan Gao; Logan Mitchell; Calvin Howes; Amie Dobracki; Ian Chang; Gonzalo Ferrada; Kristina Pistone; Samuel Leblanc; Michal Segal-Rozenhaimer; Arthur Sedlacek; Thomas Eck; Brent Holben; Pawan Gupta; Elena Lind; Paquita Zuidema; Gregory Carmichael; Connor Flynn

doi:10.5194/acp-25-7879-2025

Back

Atmospheric processing and aerosol aging responsible for observed increase in absorptivity of long-range-transported smoke over the southeast Atlantic

Journal article

Open access

Peer reviewed

Atmospheric processing and aerosol aging responsible for observed increase in absorptivity of long-range-transported smoke over the southeast Atlantic

Abdulamid Fakoya, Jens Redemann, Pablo Saide, Lan Gao, Logan Mitchell, Calvin Howes, Amie Dobracki, Ian Chang, Gonzalo Ferrada, Kristina Pistone, …

Atmospheric chemistry and physics, Vol.25(14), pp.7879-7902

07/15/2025

DOI: 10.5194/acp-25-7879-2025

Files and links (1)

url

https://doi.org/10.5194/acp-25-7879-2025View

Published (Version of record) Open Access

Abstract

Biomass burning aerosol (BBA) from agricultural fires in southern Africa contributes about one-third of the global carbonaceous aerosol load. These particles have strong radiative effects in the southeast Atlantic (SEA), which depend in part on the radiative contrast between the aerosol layer in the free troposphere (FT) and the underlying cloud layer. However, there is large disagreement in model estimates of aerosol-driven climate forcing due to uncertainties in the vertical distribution, optical properties, and life cycle of these particles. This study applies a novel method combining remote sensing observations with regional model outputs to investigate the aging of the BBA and its impact on the optical properties during transatlantic transport from emission sources in Africa to the SEA. Results show distinct variations in extinction Ångström exponent (EAE) and single-scattering albedo (SSA) as aerosols age. Near the source, fresh aerosols are characterized by low mean SSA (0.84) and high EAE (1.85), indicating smaller, highly absorbing particles. By isolating marine contributions from the total column during BBA transport across the SEA, our analysis reveals an initial decrease in BBA absorptivity, with mean FT SSA of 0.87 after 6–7 d, followed by increased absorptivity with mean FT SSA of 0.84 after 10 d, suggesting enhanced absorption due to chemical aging. These findings indicate that BBA becomes more absorbing during extended transport across the SEA, with implications for reducing model uncertainties. Our remote-sensing-based results agree well with previous in situ studies and offer new insights into aerosol–radiation interactions and the energy balance over the SEA.

Absorption

Aging

Atmospheric Aerosols

Clouds

Remote Sensing

Absorption coefficient

Absorptivity

Aerosols

Ageing

Albedo

Biomass burning

Carbon

Climate models

Energy balance

Global aerosols

Life cycle

Optical properties

Radiation

Radiative forcing

Troposphere

Uncertainty

Vertical distribution

Details

Title: Subtitle: Atmospheric processing and aerosol aging responsible for observed increase in absorptivity of long-range-transported smoke over the southeast Atlantic
Creators: Abdulamid Fakoya
Jens Redemann
Pablo Saide
Lan Gao
Logan Mitchell
Calvin Howes
Amie Dobracki
Ian Chang
Gonzalo Ferrada
Kristina Pistone
Samuel Leblanc
Michal Segal-Rozenhaimer
Arthur Sedlacek
Thomas Eck
Brent Holben
Pawan Gupta
Elena Lind
Paquita Zuidema
Gregory Carmichael
Connor Flynn
Resource Type: Journal article
Publication Details: Atmospheric chemistry and physics, Vol.25(14), pp.7879-7902
DOI: 10.5194/acp-25-7879-2025
ISSN: 1680-7316
eISSN: 1680-7324
Publisher: Copernicus GmbH
Grant note: University of Oklahoma (OU) start-up package: 122007900 NASA Earth Venture Suborbital-2 program: NNH13ZDA001N-EVS2 DOE ASR: DE-SC0021250
This research has been supported by the University of Oklahoma (OU) start-up package (grant no. 122007900). The ORACLES field campaign was funded through the NASA Earth Venture Suborbital-2 program (grant no. NNH13ZDA001N-EVS2). Paquita Zuidema acknowledges funding support from DOE ASR award DE-SC0021250.
Language: English
Date published: 07/15/2025
Academic Unit: Civil and Environmental Engineering; Nursing; Chemical and Biochemical Engineering
Record Identifier: 9984865433602771

Metrics

4 Record Views