Global observations of aerosol indirect effects from marine liquid clouds

Wall, Casey J.; Storelvmo, Trude; Possner, Anna

doi:https://doi.org/10.5194/acp-23-13125-2023

Articles | Volume 23, issue 20

https://doi.org/10.5194/acp-23-13125-2023

© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/acp-23-13125-2023

© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 23, issue 20

Research article

| Highlight paper

|

18 Oct 2023

Research article | Highlight paper |

| 18 Oct 2023

Global observations of aerosol indirect effects from marine liquid clouds

Casey J. Wall, Trude Storelvmo, and Anna Possner

Supplement

https://doi.org/10.5194/acp-23-13125-2023-supplement

Data sets

MCD06COSP_M3_MODIS, Level-1 and Atmosphere Archive and Distribution System NASA https://doi.org/10.5067/MODIS/MCD06COSP_M3_MODIS.062

Cloud droplet number concentration, calculated from the MODIS cloud optical properties retrieval and gridded using different sampling strategies E. Gryspeerdt, D. McCoy, E. Crosbie, R. H. Moore, G. J. Nott, D. Painemal, J. Small-Griswold, A. Sorooshian, and L. Ziemba https://doi.org/10.5285/864a46cc65054008857ee5bb772a2a2b

EBAF_Ed4.1 CERES https://ceres-tool.larc.nasa.gov/ord-tool/jsp/EBAF42Selection.jsp

FluxByCldTyp_Ed4.1 CERES https://ceres-tool.larc.nasa.gov/ord-tool/jsp/FluxByCldTypSelection.jsp

MERRA-2 NASA https://doi.org/10.5067/LTVB4GPCOTK2

Model code and software

RRTMG-SW Atmospheric and Environmental Research https://github.com/AER-RC/RRTMG_SW

caseywall7926/MODIS_Re-LWP_kernel: MODIS Re-LWP cloud radiative kernel (v1.0) C. J. Wall https://doi.org/10.5281/zenodo.8427293

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Executive editor

One of the largest sources of uncertainty in the overall anthropogenic forcing of climate is still the aerosol impact on liquid clouds. Disentangling the various aerosol-cloud interactions helps to improve estimates of the magnitude of global warming in the future. The current study provides the most rigorous method to date in assessing the aerosol radiative effects from satellite observations across the global ocean. The aerosol responses are decomposed into the Twomey effect (cooling due to an increase in cloud-droplet number concentration), and the adjustments of the cloud liquid water path and cloud fraction (often analysed separately) at a near-global scale. The total effective radiative forcing of liquid clouds since 1850 has been found to be negative, with the cloud adjustments larger than the Twomey effect, which was previously thought to be larger.