Atmospheric Chemistry and Physics (Jan 2022)
Opportunistic experiments to constrain aerosol effective radiative forcing
- M. W. Christensen,
- M. W. Christensen,
- A. Gettelman,
- J. Cermak,
- J. Cermak,
- G. Dagan,
- M. Diamond,
- M. Diamond,
- M. Diamond,
- A. Douglas,
- G. Feingold,
- F. Glassmeier,
- T. Goren,
- D. P. Grosvenor,
- E. Gryspeerdt,
- R. Kahn,
- Z. Li,
- P.-L. Ma,
- F. Malavelle,
- I. L. McCoy,
- I. L. McCoy,
- D. T. McCoy,
- G. McFarquhar,
- G. McFarquhar,
- J. Mülmenstädt,
- S. Pal,
- A. Possner,
- A. Povey,
- A. Povey,
- J. Quaas,
- D. Rosenfeld,
- A. Schmidt,
- A. Schmidt,
- R. Schrödner,
- A. Sorooshian,
- A. Sorooshian,
- P. Stier,
- V. Toll,
- D. Watson-Parris,
- R. Wood,
- M. Yang,
- T. Yuan,
- T. Yuan
Affiliations
- M. W. Christensen
- Atmospheric, Oceanic and Planetary Physics, Department of Physics, University of Oxford, Oxford, OX1 3PU, UK
- M. W. Christensen
- Atmospheric Science & Global Change Division, Pacific Northwest National Laboratory, Richland, WA 99354, Washington, USA
- A. Gettelman
- National Center for Atmospheric Research, Boulder, CO, USA
- J. Cermak
- Karlsruhe Institute of Technology (KIT), Institute of Meteorology and Climate Research, Karlsruhe, Germany
- J. Cermak
- Karlsruhe Institute of Technology (KIT), Institute of Photogrammetry and Remote Sensing, Karlsruhe, Germany
- G. Dagan
- Institute of Earth Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
- M. Diamond
- Department of Atmospheric Sciences, University of Washington, Seattle, USA
- M. Diamond
- NOAA Chemical Sciences Laboratory (CSL), Boulder, Colorado, USA
- M. Diamond
- Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado, Boulder, Colorado, USA
- A. Douglas
- Atmospheric, Oceanic and Planetary Physics, Department of Physics, University of Oxford, Oxford, OX1 3PU, UK
- G. Feingold
- NOAA Chemical Sciences Laboratory (CSL), Boulder, Colorado, USA
- F. Glassmeier
- Department Geoscience and Remote Sensing, Delft University of Technology, P.O. Box 5048, 2600GA Delft, the Netherlands
- T. Goren
- Institute for Meteorology, Universität Leipzig, Leipzig, Germany
- D. P. Grosvenor
- National Centre for Atmospheric Sciences, School of Earth and Environment, University of Leeds, Leeds, LS2 9JT, UK
- E. Gryspeerdt
- Space and Atmospheric Physics Group, Imperial College London, London, UK
- R. Kahn
- Earth Science Division, NASA Goddard Space Flight Center, Greenbelt, MD, USA
- Z. Li
- Department of Atmospheric and Oceanic Science, University of Maryland, College Park, USA
- P.-L. Ma
- Atmospheric Science & Global Change Division, Pacific Northwest National Laboratory, Richland, WA 99354, Washington, USA
- F. Malavelle
- Met Office, Atmospheric Dispersion and Air Quality, Fitzroy Rd, Exeter, EX1 3PB, UK
- I. L. McCoy
- Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, FL, USA
- I. L. McCoy
- Cooperative Programs for the Advancement of Earth System Science (CPAESS), University Corporation for Atmospheric Research, Boulder, CO, USA
- D. T. McCoy
- Department of Atmospheric Sciences, University of Wyoming, Laramie, USA
- G. McFarquhar
- Cooperative Institute for Severe and High Impact Weather Research and Operations (CIWRO) and School of Meteorology, University of Oklahoma, Norman, OK, USA
- G. McFarquhar
- School of Meteorology, University of Oklahoma, Norman, OK, USA
- J. Mülmenstädt
- Atmospheric Science & Global Change Division, Pacific Northwest National Laboratory, Richland, WA 99354, Washington, USA
- S. Pal
- Department of Geosciences, Texas Tech University, Lubbock, TX, USA
- A. Possner
- Institute for Atmospheric and Environmental Sciences, Goethe University Frankfurt, Frankfurt am Main, Germany
- A. Povey
- Atmospheric, Oceanic and Planetary Physics, Department of Physics, University of Oxford, Oxford, OX1 3PU, UK
- A. Povey
- National Centre for Earth Observation, University of Oxford, Oxford, OX1 3PU, UK
- J. Quaas
- Institute for Meteorology, Universität Leipzig, Leipzig, Germany
- D. Rosenfeld
- Institute of Earth Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
- A. Schmidt
- Department of Geography, University of Cambridge, Cambridge, UK
- A. Schmidt
- Department of Chemistry, University of Cambridge, Cambridge, UK
- R. Schrödner
- Leibniz Institute for Tropospheric Research, Leipzig, Germany
- A. Sorooshian
- Department of Chemical and Environmental Engineering, University of Arizona, Tucson, AZ, USA
- A. Sorooshian
- Department of Hydrology and Atmospheric Sciences, University of Arizona, Tucson, AZ, USA
- P. Stier
- Atmospheric, Oceanic and Planetary Physics, Department of Physics, University of Oxford, Oxford, OX1 3PU, UK
- V. Toll
- Institute of Physics, University of Tartu, Tartu, Estonia
- D. Watson-Parris
- Atmospheric, Oceanic and Planetary Physics, Department of Physics, University of Oxford, Oxford, OX1 3PU, UK
- R. Wood
- Department of Atmospheric Sciences, University of Washington, Seattle, USA
- M. Yang
- Plymouth Marine Laboratory, Prospect Place, Plymouth, PL1 3DH, UK
- T. Yuan
- Joint Center for Earth Systems Technologies, University of Maryland, Baltimore County, Baltimore, MD, USA
- T. Yuan
- Earth Science Division, NASA Goddard Space Flight Center, Greenbelt, MD, USA
- DOI
- https://doi.org/10.5194/acp-22-641-2022
- Journal volume & issue
-
Vol. 22
pp. 641 – 674
Abstract
Aerosol–cloud interactions (ACIs) are considered to be the most uncertain driver of present-day radiative forcing due to human activities. The nonlinearity of cloud-state changes to aerosol perturbations make it challenging to attribute causality in observed relationships of aerosol radiative forcing. Using correlations to infer causality can be challenging when meteorological variability also drives both aerosol and cloud changes independently. Natural and anthropogenic aerosol perturbations from well-defined sources provide “opportunistic experiments” (also known as natural experiments) to investigate ACI in cases where causality may be more confidently inferred. These perturbations cover a wide range of locations and spatiotemporal scales, including point sources such as volcanic eruptions or industrial sources, plumes from biomass burning or forest fires, and tracks from individual ships or shipping corridors. We review the different experimental conditions and conduct a synthesis of the available satellite datasets and field campaigns to place these opportunistic experiments on a common footing, facilitating new insights and a clearer understanding of key uncertainties in aerosol radiative forcing. Cloud albedo perturbations are strongly sensitive to background meteorological conditions. Strong liquid water path increases due to aerosol perturbations are largely ruled out by averaging across experiments. Opportunistic experiments have significantly improved process-level understanding of ACI, but it remains unclear how reliably the relationships found can be scaled to the global level, thus demonstrating a need for deeper investigation in order to improve assessments of aerosol radiative forcing and climate change.
