An assessment of methods for computing radiative forcing in climate models

Eui Seok Chung, Brian J Soden

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

Because the radiative forcing is rarely computed separately when performing climate model simulations, several alternative methods have been developed to estimate both the instantaneous (or direct) forcing and the adjusted forcing. The adjusted forcing accounts for the radiative impact arising from the adjustment of climate variables to the instantaneous forcing, independent of any surface warming. Using climate model experiments performed for CMIP5, we find the adjusted forcing for 4 xCO<inf>2</inf> ranges from roughly 5.5-9 W m<sup>-2</sup> in current models. This range is shown to be consistent between different methods of estimating the adjusted forcing. Decomposition using radiative kernels and offline double-call radiative transfer calculations indicates that the spread receives a substantial contribution (roughly 50%) from intermodel differences in the instantaneous component of the radiative forcing. Moreover, nearly all of the spread in adjusted forcing can be accounted for by differences in the instantaneous forcing and stratospheric adjustment, implying that tropospheric adjustments to CO<inf>2</inf> play only a secondary role. This suggests that differences in modeling radiative transfer are responsible for substantial differences in the projected climate response and underscores the need to archive double-call radiative transfer calculations of the instantaneous forcing as a routine diagnostic.

Original languageEnglish (US)
Article number074004
JournalEnvironmental Research Letters
Volume10
Issue number7
DOIs
StatePublished - Jul 1 2015

Fingerprint

Climate models
Radiative transfer
radiative forcing
Climate
radiative transfer
climate modeling
Upper atmosphere
climate
warming
decomposition
Decomposition
modeling
simulation
method
experiment
Experiments
calculation

Keywords

  • climate models
  • model spread
  • radiative forcing
  • radiative kernel method
  • radiative transfer
  • rapid adjustment

ASJC Scopus subject areas

  • Environmental Science(all)
  • Renewable Energy, Sustainability and the Environment
  • Public Health, Environmental and Occupational Health

Cite this

An assessment of methods for computing radiative forcing in climate models. / Chung, Eui Seok; Soden, Brian J.

In: Environmental Research Letters, Vol. 10, No. 7, 074004, 01.07.2015.

Research output: Contribution to journalArticle

@article{e980bb7c48ff4e719be0935b053900db,
title = "An assessment of methods for computing radiative forcing in climate models",
abstract = "Because the radiative forcing is rarely computed separately when performing climate model simulations, several alternative methods have been developed to estimate both the instantaneous (or direct) forcing and the adjusted forcing. The adjusted forcing accounts for the radiative impact arising from the adjustment of climate variables to the instantaneous forcing, independent of any surface warming. Using climate model experiments performed for CMIP5, we find the adjusted forcing for 4 xCO2 ranges from roughly 5.5-9 W m-2 in current models. This range is shown to be consistent between different methods of estimating the adjusted forcing. Decomposition using radiative kernels and offline double-call radiative transfer calculations indicates that the spread receives a substantial contribution (roughly 50{\%}) from intermodel differences in the instantaneous component of the radiative forcing. Moreover, nearly all of the spread in adjusted forcing can be accounted for by differences in the instantaneous forcing and stratospheric adjustment, implying that tropospheric adjustments to CO2 play only a secondary role. This suggests that differences in modeling radiative transfer are responsible for substantial differences in the projected climate response and underscores the need to archive double-call radiative transfer calculations of the instantaneous forcing as a routine diagnostic.",
keywords = "climate models, model spread, radiative forcing, radiative kernel method, radiative transfer, rapid adjustment",
author = "Chung, {Eui Seok} and Soden, {Brian J}",
year = "2015",
month = "7",
day = "1",
doi = "10.1088/1748-9326/10/7/074004",
language = "English (US)",
volume = "10",
journal = "Environmental Research Letters",
issn = "1748-9326",
publisher = "IOP Publishing Ltd.",
number = "7",

}

TY - JOUR

T1 - An assessment of methods for computing radiative forcing in climate models

AU - Chung, Eui Seok

AU - Soden, Brian J

PY - 2015/7/1

Y1 - 2015/7/1

N2 - Because the radiative forcing is rarely computed separately when performing climate model simulations, several alternative methods have been developed to estimate both the instantaneous (or direct) forcing and the adjusted forcing. The adjusted forcing accounts for the radiative impact arising from the adjustment of climate variables to the instantaneous forcing, independent of any surface warming. Using climate model experiments performed for CMIP5, we find the adjusted forcing for 4 xCO2 ranges from roughly 5.5-9 W m-2 in current models. This range is shown to be consistent between different methods of estimating the adjusted forcing. Decomposition using radiative kernels and offline double-call radiative transfer calculations indicates that the spread receives a substantial contribution (roughly 50%) from intermodel differences in the instantaneous component of the radiative forcing. Moreover, nearly all of the spread in adjusted forcing can be accounted for by differences in the instantaneous forcing and stratospheric adjustment, implying that tropospheric adjustments to CO2 play only a secondary role. This suggests that differences in modeling radiative transfer are responsible for substantial differences in the projected climate response and underscores the need to archive double-call radiative transfer calculations of the instantaneous forcing as a routine diagnostic.

AB - Because the radiative forcing is rarely computed separately when performing climate model simulations, several alternative methods have been developed to estimate both the instantaneous (or direct) forcing and the adjusted forcing. The adjusted forcing accounts for the radiative impact arising from the adjustment of climate variables to the instantaneous forcing, independent of any surface warming. Using climate model experiments performed for CMIP5, we find the adjusted forcing for 4 xCO2 ranges from roughly 5.5-9 W m-2 in current models. This range is shown to be consistent between different methods of estimating the adjusted forcing. Decomposition using radiative kernels and offline double-call radiative transfer calculations indicates that the spread receives a substantial contribution (roughly 50%) from intermodel differences in the instantaneous component of the radiative forcing. Moreover, nearly all of the spread in adjusted forcing can be accounted for by differences in the instantaneous forcing and stratospheric adjustment, implying that tropospheric adjustments to CO2 play only a secondary role. This suggests that differences in modeling radiative transfer are responsible for substantial differences in the projected climate response and underscores the need to archive double-call radiative transfer calculations of the instantaneous forcing as a routine diagnostic.

KW - climate models

KW - model spread

KW - radiative forcing

KW - radiative kernel method

KW - radiative transfer

KW - rapid adjustment

UR - http://www.scopus.com/inward/record.url?scp=84934326510&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84934326510&partnerID=8YFLogxK

U2 - 10.1088/1748-9326/10/7/074004

DO - 10.1088/1748-9326/10/7/074004

M3 - Article

AN - SCOPUS:84934326510

VL - 10

JO - Environmental Research Letters

JF - Environmental Research Letters

SN - 1748-9326

IS - 7

M1 - 074004

ER -