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Decomposing Effective Radiative Forcing due to Aerosol Cloud Interactions by Global Cloud Regimes
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  • Tom Langton,
  • Philip Stier,
  • Duncan Watson-Parris,
  • Jane Patricia Mulcahy
Tom Langton
University of Oxford

Corresponding Author:[email protected]

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Philip Stier
University of Oxford
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Duncan Watson-Parris
University of Oxford
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Jane Patricia Mulcahy
Met Office Hadley Centre
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Abstract

Quantifying Effective Radiative Forcing due to aerosol-cloud interactions (ERFACI) remains a largely uncertain process, and the magnitude remains unconstrained in general circulation models. Previous studies focus on the magnitude of ERFACI arising from all cloud types, or examine it in the framework of dynamical regimes. Aerosol forcing due to aerosol-cloud interactions in the HadGEM3-GA7.1 global climate model is decomposed into several global observational cloud regimes. Regimes are allocated to model gridboxes and forcing due to aerosol-cloud interactions is calculated on a regime-by-regime basis with a 20-year meaning period. Patterns of regime occurrence are in good agreement with satellite observations. ERFACI is then further decomposed into three terms, representing radiative changes within a given regime, transitions between different cloud regimes, and nonlinear effects. The total global mean ERFACI is -1.8 Wm-2. When decomposed, simulated ERFACI is greatest in the stratocumulus regime (-0.75 Wm-2).
28 Sep 2021Published in Geophysical Research Letters volume 48 issue 18. 10.1029/2021GL093833