Mass Absorption Cross-Section of Ambient Black Carbon Aerosols - a Review

Abstract

An accurate assessment of black carbon (BC) climate and health impacts requires knowledge of its mass absorption cross-section (MAC_BC) – a parameter linking optical and mass measurements. The mean MAC_BC for freshly emitted soot typically spans a narrow range of 8 m² g⁻¹ at 550 nm but is modified by subsequent atmospheric aging. Determination of MAC_BC requires simultaneous measurements of aerosol light-absorption coefficient (β_abs) and BC mass. Here, we compile 230 measured MAC_BC values from 80 atmospheric studies and explore the effects of sampling location, study duration, instrumentation, and measurement wavelength. The compiled data set shows a broad variability in MAC_BC values (a factor of about 200 %). We conclude that this variability is attributable to a combination of the above-mentioned effects with additional instrumental uncertainties (e.g., cross-sensitivities and/or inadequate instrument calibration). The current state of knowledge does not support the use of simplistic generalizations or assumptions about MAC_BC in the atmosphere, motivating a recommendation to further improve and standardize measurement practices.

Taxonomía de las mediciones de carbono negro. Incluye mediciones ópticas y de masa de carbono elemental y refractario.

Citation

@article{asmiMassAbsorptionCrosssection2025,
  title = {Mass Absorption Cross-Section of Ambient Black Carbon Aerosols - a Review},
  author = {Asmi, Eija and Sipkens, Timothy A. and Saturno, Jorge and Backman, John and Vasilatou, Konstantina and Weingartner, Ernest and Keller, Alejandro and Ciupek, Krzysztof and Müller, Thomas and Babu Suja, Arun and Močnik, Griša and Drinovec, Luka and Eleftheriadis, Konstantinos and Gini, Maria I. and Nowak, Andreas and Corbin, Joel C.},
  year = 2025,
  month = dec,
  journal = {npj Climate and Atmospheric Science},
  publisher = {Nature Publishing Group},
  issn = {2397-3722},
  doi = {10.1038/s41612-025-01288-2},
  urldate = {2026-01-05},
  abstract = {An accurate assessment of black carbon (BC) climate and health impacts requires knowledge of its mass absorption cross-section (MACBC) -- a parameter linking optical and mass measurements. The mean MACBC for freshly emitted soot typically spans a narrow range of 8 m² g-1 at 550 nm but is modified by subsequent atmospheric aging. Determination of MACBC requires simultaneous measurements of aerosol light-absorption coefficient (babs) and BC mass. Here, we compile 230 measured MACBC values from 80 atmospheric studies and explore the effects of sampling location, study duration, instrumentation, and measurement wavelength. The compiled data set shows a broad variability in MACBC values (a factor of about 200 %). We conclude that this variability is attributable to a combination of the above-mentioned effects with additional instrumental uncertainties (e.g., cross-sensitivities and/or inadequate instrument calibration). The current state of knowledge does not support the use of simplistic generalizations or assumptions about MACBC in the atmosphere, motivating a recommendation to further improve and standardize measurement practices.},
  copyright = {2025 The Author(s)},
  langid = {english},
  keywords = {Climate sciences,Environmental sciences,Optics and photonics,Physics}
}