Publication Abstracts

Koch et al. 2011

Koch, D., Y. Balkanski, S.E. Bauer, R.C. Easter, S. Ferrachat, S.J. Ghan, C. Hoose, T. Iversen, A. Kirkevåg, J.E. Kristjansson, X. Liu, U. Lohmann, S. Menon, J. Quaas, M. Schulz, Ø. Seland, T. Takemura, and N. Yan, 2011: Soot microphysical effects on liquid clouds, a multi-model investigation. Atmos. Chem. Phys., 11, 1051-1064, doi:10.5194/acp-11-1051-2011.

We use global models to explore the microphysical effects of carbonaceous aerosols on clouds. Although absorption of solar radiation by soot warms the atmosphere, soot may cause climate cooling due to its contribution to cloud condensation nuclei (CCN) and therefore cloud brightness. Six global models conducted three soot experiments; four of the models had detailed aerosol microphysical schemes. The average cloud radiative response to biofuel soot (black and organic carbon), including both indirect and semi-direct effects, is -0.11 Wm-2, comparable in size but opposite in sign to the respective direct effect. In a more idealized fossil fuel black carbon experiment, some models calculated a positive cloud response because soot provides a deposition sink for sulfuric and nitric acids and secondary organics, decreasing nucleation and evolution of viable CCN. Biofuel soot particles were also typically assumed to be larger and more hygroscopic than for fossil fuel soot and therefore caused more negative forcing, as also found in previous studies. Diesel soot (black and organic carbon) experiments had relatively smaller cloud impacts with five of the models < ±0.06 Wm-2 from clouds. The results are subject to the caveats that variability among models, and regional and interrannual variability for each model, are large. This comparison together with previously published results stresses the need to further constrain aerosol microphysical schemes. The non-linearities resulting from the competition of opposing effects on the CCN population make it difficult to extrapolate from idealized experiments to likely impacts of realistic potential emission changes.

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BibTeX Citation

  author={Koch, D. and Balkanski, Y. and Bauer, S. E. and Easter, R. C. and Ferrachat, S. and Ghan, S. J. and Hoose, C. and Iversen, T. and Kirkevåg, A. and Kristjansson, J. E. and Liu, X. and Lohmann, U. and Menon, S. and Quaas, J. and Schulz, M. and Seland, Ø. and Takemura, T. and Yan, N.},
  title={Soot microphysical effects on liquid clouds, a multi-model investigation},
  journal={Atmos. Chem. Phys.},

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RIS Citation

ID  - ko09300d
AU  - Koch, D.
AU  - Balkanski, Y.
AU  - Bauer, S. E.
AU  - Easter, R. C.
AU  - Ferrachat, S.
AU  - Ghan, S. J.
AU  - Hoose, C.
AU  - Iversen, T.
AU  - Kirkevåg, A.
AU  - Kristjansson, J. E.
AU  - Liu, X.
AU  - Lohmann, U.
AU  - Menon, S.
AU  - Quaas, J.
AU  - Schulz, M.
AU  - Seland, Ø.
AU  - Takemura, T.
AU  - Yan, N.
PY  - 2011
TI  - Soot microphysical effects on liquid clouds, a multi-model investigation
JA  - Atmos. Chem. Phys.
VL  - 11
SP  - 1051
EP  - 1064
DO  - 10.5194/acp-11-1051-2011
ER  -

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