Biomass burning aerosols in most climate models are too absorbing

Brown, H., Liu, X., Pokhrel, R., Murphy, S., Lu, Z., Saleh, R., Mielonen, T., Kokkola, H., Bergman, T., Myhre, G., Skeie, R. B., Watson-Paris, D., Stier, P., Johnson, B., Bellouin, N. ORCID: https://orcid.org/0000-0003-2109-9559, Schulz, M., Vakkari, V., Beukes, J. P., van Zyl, P. G., Liu, S. and Chand, D. (2021) Biomass burning aerosols in most climate models are too absorbing. Nature Communications, 12 (1). 277. ISSN 2041-1723 doi: 10.1038/s41467-020-20482-9

Abstract/Summary

Uncertainty in the representation of biomass burning (BB) aerosol composition and optical properties in climate models contributes to a range in modeled aerosol effects on incoming solar radiation. Depending on the model, the top-of-the-atmosphere BB aerosol effect can range from cooling to warming. By relating aerosol absorption relative to extinction and carbonaceous aerosol composition from observational datasets to nine state-of-the-art Earth System Models/Chemical Transport Models,we identify varying degrees of overestimation in BB aerosol absorptivity by these models. Modifications to BB aerosol refractive index, size, and mixing state improve the Community Atmosphere Model version 5 (CAM5) agreement with observations, leading to a global change in BB direct radiative effect of -0.07 W m-2,and regional changes of -2 W m-2(Africa) and -0.5 W m-2(South America/Temperate). Our findings suggest that current modeled BB contributes less to warming than previously thought, largely due to treatments of aerosol mixing state.

Item Type	Article
URI	https://reading-clone.eprints-hosting.org/id/eprint/94726
Identification Number/DOI	10.1038/s41467-020-20482-9
Refereed	Yes
Divisions	Science > School of Mathematical, Physical and Computational Sciences > Department of Meteorology
Publisher	Nature Publishing Group
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