Diagrams from the paper.
Conceptual schematics of (a) the conventional homogeneous core-shell (CS) treatment and (b) the new Advanced Black Carbon (ABC) for black carbon (BC) in aerosol optical simulations of Community Atmosphere Model version 6. (a) The CS treatments are characterized as small BC size, thick coating, and 100% proportion of BC-containing particles, leading to artificial absorption enhancement. (b) The new ABC adopts the observed BC size distribution and mixing states, with only a certain fraction of accumulated particles encapsulating the BC component. Credit: Chen et al. [2023], Figure 4
Editors’ Highlights are summaries of recent papers by AGU’s journal editors.
Source: Journal of Advances in Modeling Earth Systems

Black carbon (BC) is a major light absorption component and strong climate-warming agent among atmospheric aerosols. Aerosol absorption efficiency and their global warming effects were reported to be overestimated in current global climate models (GCMs) due to the poor representation of complex BC mixing states.

To quantify the aerosol representation deficiency in GCMs due to the microphysical and optical properties and improve the BC and aerosol optical property representation, Chen et al. [2023] analyze and summarize the key BC properties that highly influence their radiative effects based on multi-source observations of particle size distribution and mixing state. Subsequently, they develop an improved aerosol optical model to better account for those observations, and implement this representation in a GCM. Field observations are used to evaluate the new model incorporating the improved BC and aerosol optical property representations.

The results show that the predicted BC absorption from the improved representations has better agreement with global BC observations due to more accurately predicted BC-related microphysical and mixing properties. Correspondingly, the improved BC representation reduced the BC radiative forcing and climate effects by as much as 24 per cent.

Citation: Chen, G., Wang, J., Wang, Y., Wang, J., Jin, Y., Cheng, Y., et al. (2023). An aerosol optical module with observation-constrained black carbon properties for global climate models. Journal of Advances in Modeling Earth Systems, 15, e2022MS003501. https://doi.org/10.1029/2022MS003501  

—Jiwen Fan, Editor, JAMES

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