Uncertainty in aerosol–cloud radiative forcing is driven by clean conditions
<p>Atmospheric aerosols and their impact on cloud properties remain the largest uncertainty in the human forcing of the climate system. By increasing the concentration of cloud droplets (<span class="inline-formula"><i>N</i><sub>d</sub></span>), ae...
| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2023-04-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://acp.copernicus.org/articles/23/4115/2023/acp-23-4115-2023.pdf |
| _version_ | 1797851715402203136 |
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| author | E. Gryspeerdt A. C. Povey R. G. Grainger O. Hasekamp N. C. Hsu J. P. Mulcahy A. M. Sayer A. M. Sayer A. Sorooshian |
| author_facet | E. Gryspeerdt A. C. Povey R. G. Grainger O. Hasekamp N. C. Hsu J. P. Mulcahy A. M. Sayer A. M. Sayer A. Sorooshian |
| author_sort | E. Gryspeerdt |
| collection | DOAJ |
| description | <p>Atmospheric aerosols and their impact on cloud properties remain the
largest uncertainty in the human forcing of the climate system. By
increasing the concentration of cloud droplets (<span class="inline-formula"><i>N</i><sub>d</sub></span>), aerosols
reduce droplet size and increase the reflectivity of clouds (a
negative radiative forcing). Central to this climate impact is the
susceptibility of cloud droplet number to aerosol (<span class="inline-formula"><i>β</i></span>), the
diversity of which explains much of the variation in the radiative
forcing from aerosol–cloud interactions (RFaci) in global climate
models. This has made measuring <span class="inline-formula"><i>β</i></span> a key target for developing
observational constraints of the aerosol forcing.</p>
<p>While the aerosol burden of the clean, pre-industrial atmosphere has
been demonstrated as a key uncertainty for the aerosol forcing, here
we show that the behaviour of clouds under these clean conditions is
of equal importance for understanding the spread in radiative
forcing estimates between models and observations. This means that
the uncertainty in the aerosol impact on clouds is,
counterintuitively, driven by situations with little
aerosol. Discarding clean conditions produces a close agreement
between different model and observational estimates of the cloud
response to aerosol but does not provide a strong constraint on the
RFaci. This makes constraining aerosol behaviour in clean conditions
an important goal for future observational studies.</p> |
| first_indexed | 2024-04-09T19:21:10Z |
| format | Article |
| id | doaj.art-6afbc7d57ae14e55ac522f316c617e2d |
| institution | Directory Open Access Journal |
| issn | 1680-7316 1680-7324 |
| language | English |
| last_indexed | 2024-04-09T19:21:10Z |
| publishDate | 2023-04-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Atmospheric Chemistry and Physics |
| spelling | doaj.art-6afbc7d57ae14e55ac522f316c617e2d2023-04-05T10:01:09ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242023-04-01234115412210.5194/acp-23-4115-2023Uncertainty in aerosol–cloud radiative forcing is driven by clean conditionsE. Gryspeerdt0A. C. Povey1R. G. Grainger2O. Hasekamp3N. C. Hsu4J. P. Mulcahy5A. M. Sayer6A. M. Sayer7A. Sorooshian8Grantham Institute – Climate Change and the Environment, Imperial College London, London, SW7 2AZ, UKNational Centre for Earth Observation, Department of Physics, University of Oxford, Oxford, OX1 3PU, UKNational Centre for Earth Observation, Department of Physics, University of Oxford, Oxford, OX1 3PU, UKNetherlands Institute for Space Research (SRON, NWO-I), Niels Bohrweg 4, 2333 CA Leiden, the NetherlandsClimate and Radiation Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USAMet Office, Exeter, EX1 3PB, UKOcean Ecology Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USAGESTAR II, University of Maryland Baltimore County, Baltimore, MD 21250, USADepartment of Chemical and Environmental Engineering, University of Arizona, Tucson, AZ, USA<p>Atmospheric aerosols and their impact on cloud properties remain the largest uncertainty in the human forcing of the climate system. By increasing the concentration of cloud droplets (<span class="inline-formula"><i>N</i><sub>d</sub></span>), aerosols reduce droplet size and increase the reflectivity of clouds (a negative radiative forcing). Central to this climate impact is the susceptibility of cloud droplet number to aerosol (<span class="inline-formula"><i>β</i></span>), the diversity of which explains much of the variation in the radiative forcing from aerosol–cloud interactions (RFaci) in global climate models. This has made measuring <span class="inline-formula"><i>β</i></span> a key target for developing observational constraints of the aerosol forcing.</p> <p>While the aerosol burden of the clean, pre-industrial atmosphere has been demonstrated as a key uncertainty for the aerosol forcing, here we show that the behaviour of clouds under these clean conditions is of equal importance for understanding the spread in radiative forcing estimates between models and observations. This means that the uncertainty in the aerosol impact on clouds is, counterintuitively, driven by situations with little aerosol. Discarding clean conditions produces a close agreement between different model and observational estimates of the cloud response to aerosol but does not provide a strong constraint on the RFaci. This makes constraining aerosol behaviour in clean conditions an important goal for future observational studies.</p>https://acp.copernicus.org/articles/23/4115/2023/acp-23-4115-2023.pdf |
| spellingShingle | E. Gryspeerdt A. C. Povey R. G. Grainger O. Hasekamp N. C. Hsu J. P. Mulcahy A. M. Sayer A. M. Sayer A. Sorooshian Uncertainty in aerosol–cloud radiative forcing is driven by clean conditions Atmospheric Chemistry and Physics |
| title | Uncertainty in aerosol–cloud radiative forcing is driven by clean conditions |
| title_full | Uncertainty in aerosol–cloud radiative forcing is driven by clean conditions |
| title_fullStr | Uncertainty in aerosol–cloud radiative forcing is driven by clean conditions |
| title_full_unstemmed | Uncertainty in aerosol–cloud radiative forcing is driven by clean conditions |
| title_short | Uncertainty in aerosol–cloud radiative forcing is driven by clean conditions |
| title_sort | uncertainty in aerosol cloud radiative forcing is driven by clean conditions |
| url | https://acp.copernicus.org/articles/23/4115/2023/acp-23-4115-2023.pdf |
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