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Transient Climate Response in Coupled Atmospheric–Ocean General Circulation Models

Liang, Mao-Chang and Lin, Li-Ching and Tung, Ka-Kit and Yung, Yuk L. and Sun, Shan (2013) Transient Climate Response in Coupled Atmospheric–Ocean General Circulation Models. Journal of the Atmospheric Sciences, 70 (4). pp. 1291-1296. ISSN 0022-4928. http://resolver.caltech.edu/CaltechAUTHORS:20130502-131813872

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Abstract

The equilibrium climate sensitivity (ECS) has a large uncertainty range among models participating in the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4) and has recently been presented as “inherently unpredictable.” One way to circumvent this problem is to consider the transient climate response (TCR). However, the TCR among AR4 models also differs by more than a factor of 2. The authors argue that the situation may not necessarily be so pessimistic, because much of the intermodel difference may be due to the fact that the models were run with their oceans at various stages of flux adjustment with their atmosphere. This is shown by comparing multimillennium-long runs of the Goddard Institute for Space Studies model, version E, coupled with the Hybrid Coordinate Ocean Model (GISS-EH) and the Community Climate System Model, version 4 (CCSM4) with what were reported to AR4. The long model runs here reveal the range of variability (~30%) in their TCR within the same model with the same ECS. The commonly adopted remedy of subtracting the “climate drift” is ineffective and adds to the variability. The culprit is the natural variability of the control runs, which exists even at quasi equilibration. Fortunately, for simulations with multidecadal time horizon, robust solutions can be obtained by branching off thousand-year-long control runs that reach “quasi equilibration” using a new protocol, which takes advantage of the fact that forced solutions to radiative forcing forget their initial condition after 30–40 yr and instead depend mostly on the trajectory of the radiative forcing.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1175/JAS-D-12-0338.1DOIArticle
http://journals.ametsoc.org/doi/abs/10.1175/JAS-D-12-0338.1PublisherArticle
Additional Information:© 2013 American Meteorological Society. Received: December 11, 2012; accepted: January 10, 2013. The research is performed using high performance computing resources provided byASCC and ASGC. This work is supported in part by NSC Grant 101-2628-M-001-001-MY4 to Academia Sinica. KKT’s research is supported by National Science Foundation, under Grant DMS 0940342, and the National Aeronautics and Space Administration, under Grant NNX11AC75G. YLY acknowledges support from the KISS program at the California Institute of Technology.
Group:Keck Institute for Space Studies
Funders:
Funding AgencyGrant Number
National Science Council (Taipei)101-2628-M-001-001-MY4
NSFDMS-0940342
NASANNX11AC75G
Keck Institute for Space Studies (KISS)UNSPECIFIED
Subject Keywords:Climate prediction; Climate sensitivity; Climate models
Record Number:CaltechAUTHORS:20130502-131813872
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20130502-131813872
Official Citation:Liang, Mao-Chang, Li-Ching Lin, Ka-Kit Tung, Yuk L. Yung, Shan Sun, 2013: Transient Climate Response in Coupled Atmospheric–Ocean General Circulation Models. J. Atmos. Sci., 70, 1291–1296. doi: http://dx.doi.org/10.1175/JAS-D-12-0338.1
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:38243
Collection:CaltechAUTHORS
Deposited By: Jason Perez
Deposited On:03 May 2013 18:26
Last Modified:31 Oct 2017 18:20

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