Forster, P orcid.org/0000-0002-6078-0171, Richardson, T orcid.org/0000-0002-3947-9915, Maycock, AC orcid.org/0000-0002-6614-1127 et al. (6 more authors) (2016) Recommendations for diagnosing effective radiative forcing from climate models for CMIP6. Journal of Geophysical Research: Atmospheres, 121 (20). pp. 12460-12475. ISSN 2169-897X
Abstract
The usefulness of previous Coupled Model Intercomparison Project (CMIP) exercises has been hampered by a lack of radiative forcing information. This has made it difficult to understand reasons for differences between model responses. Effective radiative forcing (ERF) is easier to diagnose than traditional radiative forcing in global climate models (GCMs) and is more representative of the eventual temperature response. Here we examine the different methods of computing ERF in two GCMs. We find that ERF computed from a fixed sea-surface temperature (SST) method (ERF_fSST) has much more certainty than regression based methods. Thirty-year integrations are sufficient to reduce the 5-95% confidence interval in global ERF_fSST to 0.1 W m-2. For 2xCO2 ERF, 30 year integrations are needed to ensure that the signal is larger than the local confidence interval over more than 90% of the globe. Within the ERF_fSST method there are various options for prescribing SSTs and sea-ice. We explore these and find that ERF is only weakly dependent on the methodological choices. Prescribing the monthly-averaged seasonally varying model’s preindustrial climatology is recommended for its smaller random error and easier implementation. As part of CMIP6, the Radiative Forcing Model Intercomparison Project (RFMIP) asks models to conduct 30-year ERF_fSST experiments using the model’s own preindustrial climatology of SST and sea-ice. The Aerosol and Chemistry Model Intercomparison Project (AerChemMIP) will also mainly use this approach. We propose this as a standard method for diagnosing ERF and recommend that it be used across the climate modelling community to aid future comparisons.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2016. The Authors. This is an open access article under the terms of the Creative Commons Attribution License (CC-BY 4.0), which permits unrestricted use, distribution and reproduction in any medium, provided the original work is properly cited. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/. |
Keywords: | Radiative forcing; effective radiative forcing; RFMIP; CMIP6; climate models; AerChemMIP |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds) > Inst for Climate & Atmos Science (ICAS) (Leeds) |
Funding Information: | Funder Grant number US Department of Energy Project 1552083 NERC NE/M017176/1 NERC NE/M018199/1 NERC NE/N006038/1 ECMRWF European Centre Medium No ref number |
Depositing User: | Symplectic Publications |
Date Deposited: | 16 Feb 2017 15:25 |
Last Modified: | 04 Jun 2019 18:38 |
Published Version: | http://doi.org/10.1002/2016JD025320 |
Status: | Published |
Publisher: | American Geophysical Union (AGU) |
Identification Number: | 10.1002/2016JD025320 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:111875 |
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