Preprints
https://doi.org/10.5194/egusphere-2023-689
https://doi.org/10.5194/egusphere-2023-689
25 Apr 2023
 | 25 Apr 2023

Aerosol Effective Radiative Forcings in CMIP Models

Mark D. Zelinka, Christopher J. Smith, Yi Qin, and Karl E. Taylor

Abstract. Uncertainty in the effective radiative forcing (ERF) of climate primarily arises from the unknown contribution of aerosols, which impact radiative fluxes directly and through modifying cloud properties. Climate model simulations with fixed sea surface temperatures but perturbed atmospheric aerosol loadings allow for an estimate of how strongly the planet’s radiative energy budget has been perturbed by the increase in aerosols since pre-industrial times. The approximate partial radiative perturbation (APRP) technique further decomposes the contributions to the direct forcing from aerosol scattering and absorption, and to the indirect forcing from aerosol-induced changes in cloud scattering, amount, and absorption, as well as the effects of aerosols on surface albedo. Here we evaluate previously published APRP-derived estimates of aerosol effective radiative forcings from these simulations and find that they are slightly biased as a result of large but compensating errors. These biases are largest for the aerosol direct effect owing to underestimated aerosol absorption. Correcting these biases eliminates the residuals and leads to better agreement with ground-truth estimates derived from double-calls to the radiation code. The APRP method – when properly implemented – remains a highly accurate and efficient technique for diagnosing aerosol ERF in cases where double radiation calls are not available, and in all cases it provides quantification of the individual contributors to the ERF that are highly useful but not otherwise available.

Journal article(s) based on this preprint

09 Aug 2023
Comparison of methods to estimate aerosol effective radiative forcings in climate models
Mark D. Zelinka, Christopher J. Smith, Yi Qin, and Karl E. Taylor
Atmos. Chem. Phys., 23, 8879–8898, https://doi.org/10.5194/acp-23-8879-2023,https://doi.org/10.5194/acp-23-8879-2023, 2023
Short summary

Mark D. Zelinka et al.

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-689', Anonymous Referee #1, 17 May 2023
  • RC2: 'Comment on egusphere-2023-689', Anonymous Referee #2, 30 May 2023
  • AC1: 'Comment on egusphere-2023-689', Mark Zelinka, 19 Jun 2023

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-689', Anonymous Referee #1, 17 May 2023
  • RC2: 'Comment on egusphere-2023-689', Anonymous Referee #2, 30 May 2023
  • AC1: 'Comment on egusphere-2023-689', Mark Zelinka, 19 Jun 2023

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload
AR by Mark Zelinka on behalf of the Authors (20 Jun 2023)  Author's response   Author's tracked changes   Manuscript 
ED: Publish as is (22 Jun 2023) by Yuan Wang
AR by Mark Zelinka on behalf of the Authors (23 Jun 2023)

Journal article(s) based on this preprint

09 Aug 2023
Comparison of methods to estimate aerosol effective radiative forcings in climate models
Mark D. Zelinka, Christopher J. Smith, Yi Qin, and Karl E. Taylor
Atmos. Chem. Phys., 23, 8879–8898, https://doi.org/10.5194/acp-23-8879-2023,https://doi.org/10.5194/acp-23-8879-2023, 2023
Short summary

Mark D. Zelinka et al.

Mark D. Zelinka et al.

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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.

Short summary
The primary uncertainty in how strongly Earth's climate has been perturbed by human activities comes from the unknown radiative impact of aerosol changes. Accurately quantifying these forcings – and their sub-components – in climate models is crucial for understanding the past and future simulated climate. In this study we describe biases in previously published estimates of aerosol radiative forcing in climate models and provide corrected estimates along with code for users to compute them.