Document Type
Article
Publication Date
1-27-2020
Department
Department of Physics
Abstract
Black carbon (BC) absorbs solar radiation, leading to a strong but uncertain warming effect on climate. A key challenge in modeling and quantifying BC’s radiative effect on climate is predicting enhancements in light absorption that result from internal mixing between BC and other aerosol components. Modeling and laboratory studies show that BC, when mixed with other aerosol components, absorbs more strongly than pure, uncoated BC; however, some ambient observations suggest more variable and weaker absorption enhancement. We show that the lower-than-expected enhancements in ambient measurements result from a combination of two factors. First, the often used spherical, concentric core-shell approximation generally overestimates the absorption by BC. Second, and more importantly, inadequate consideration of heterogeneity in particle-to-particle composition engenders substantial overestimation in absorption by the total particle population, with greater heterogeneity associated with larger model–measurement differences. We show that accounting for these two effects—variability in per-particle composition and deviations from the core-shell approximation—reconciles absorption enhancement predictions with laboratory and field observations and resolves the apparent discrepancy. Furthermore, our consistent model framework provides a path forward for improving predictions of BC’s radiative effect on climate.
Publication Title
Proceedings of the National Academy of Sciences of the United States of America
Recommended Citation
Fierce, L.,
Onasch, T. B.,
Cappa, C. D.,
Mazzoleni, C.,
China, S.,
Bhandari, J.,
&
et al.
(2020).
Radiative absorption enhancements by black carbon controlled by particle-to-particle heterogeneity in composition.
Proceedings of the National Academy of Sciences of the United States of America,
117(10), 5196-5203.
http://doi.org/10.1073/pnas.1919723117
Retrieved from: https://digitalcommons.mtu.edu/michigantech-p/1854
Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial-No Derivative Works 4.0 International License.
Version
Publisher's PDF
Publisher's Statement
Copyright © 2020 the Author(s). Published by PNAS. This open access article is distributed under Creative Commons Attribution-Non Commercial No Derivatives License 4.0 (CC BY-NC-ND). Publisher’s version of record: https://doi.org/10.1073/pnas.1919723117