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Interpreting the Dependence of Cloud-Radiative Adjustment on Forcing Agent
  • Pietro Salvi,
  • Paulo Ceppi,
  • Jonathan M. Gregory
Pietro Salvi
Imperial College London

Corresponding Author:pietro.salvi14@imperial.ac.uk

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Paulo Ceppi
Imperial College London
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Jonathan M. Gregory
University of Reading
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Effective radiative forcing includes a contribution by rapid adjustments, i.e. changes in temperature, water vapour and clouds that modify the energy budget. Cloud adjustments in particular have been shown to depend strongly on forcing agent. We perform idealised atmospheric heating experiments to demonstrate a relationship between cloud adjustment and the vertical profile of imposed radiative heating: boundary-layer heating causes a positive cloud adjustment, while free-tropospheric heating yields a negative adjustment. This dependence is dominated by the shortwave effect of changes in low clouds. Much of the variation in cloud adjustment among realistic forcing agents such as CO2, CH4, solar forcing, and black carbon is explained by the “characteristic altitude” of the heating profile, through its effect on tropospheric stability.
28 Sep 2021Published in Geophysical Research Letters volume 48 issue 18. 10.1029/2021GL093616