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Title: Long-Term Behavior of the Atlantic Interhemispheric SST Gradient in the CMIP5 Historical Simulations

Abstract

Multidecadal and longer changes to the Atlantic interhemispheric sea surface temperature gradient (AITG) in phase 5 of the Coupled Model Intercomparison Project (CMIP5) historical simulations are investigated. Observations show a secular trend to this gradient over most of the twentieth century, with the southern lobe warming faster relative to its northern counterpart. A previous study of phase 3 of the CMIP (CMIP3) suggests that this trend is partially forced by anthropogenic sulfate aerosols. This analysis collectively confirms the partially forced trend for the CMIP5 and by anthropogenic aerosols. Like the CMIP3, the CMIP5 also simulates a reversal in the AITG trend in the late 1970s, which was attributed to a leveling offof the anthropogenic aerosol influence and increased influence of greenhouse gases in the late twentieth century. Two (of 25) CMIP5 models, however, systematically simulate a twentieth-century trend opposite to observed, leading to some uncertainty regarding the forced nature of the AITG trend. Here, the observed AITG also exhibits a pronounced multidecadal modulation on top of the trend, associated with the Atlantic multidecadal oscillation (AMO). Motivated by a recent suggestion that the AMO is a forced response to aerosols, the causes of this multidecadal behavior were also examined. A fewmore » of the CMIP5 models analyzed do produce multidecadal AITG variations that are correlated to the observed AMO-like variation, but only one, the Hadley Centre Global Environmental Model, version 2 (HadGEM2), systematically simulates AMO-like behavior with both the requisite amplitude and phase. The CMIP5 simulations thus point to a robust aerosol influence on the historical AITG trend but not to the AMO-like multidecadal behavior.« less

Authors:
 [1];  [2];  [3]
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  1. Univ. of California Berkeley, Berkeley, CA (United States)
  2. Univ. of California Berkeley, Berkeley, CA (United States); Risk Management Solutions, Fremont, CA (United States)
  3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1523861
Grant/Contract Number:  
AC02-05CH11231
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Climate
Additional Journal Information:
Journal Volume: 26; Journal Issue: 21; Journal ID: ISSN 0894-8755
Publisher:
American Meteorological Society
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; Atlantic Ocean; Atmosphere-ocean interaction; Climate variability; Coupled models; Multidecadal variability; Trends

Citation Formats

Chiang, John C. H., Chang, C. -Y., and Wehner, M. F. Long-Term Behavior of the Atlantic Interhemispheric SST Gradient in the CMIP5 Historical Simulations. United States: N. p., 2013. Web. doi:10.1175/JCLI-D-12-00487.1.
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Chiang, John C. H., Chang, C. -Y., & Wehner, M. F. Long-Term Behavior of the Atlantic Interhemispheric SST Gradient in the CMIP5 Historical Simulations. United States. doi:10.1175/JCLI-D-12-00487.1.
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Chiang, John C. H., Chang, C. -Y., and Wehner, M. F. Wed . "Long-Term Behavior of the Atlantic Interhemispheric SST Gradient in the CMIP5 Historical Simulations". United States. doi:10.1175/JCLI-D-12-00487.1. https://www.osti.gov/servlets/purl/1523861.
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@article{osti_1523861,
title = {Long-Term Behavior of the Atlantic Interhemispheric SST Gradient in the CMIP5 Historical Simulations},
author = {Chiang, John C. H. and Chang, C. -Y. and Wehner, M. F.},
abstractNote = {Multidecadal and longer changes to the Atlantic interhemispheric sea surface temperature gradient (AITG) in phase 5 of the Coupled Model Intercomparison Project (CMIP5) historical simulations are investigated. Observations show a secular trend to this gradient over most of the twentieth century, with the southern lobe warming faster relative to its northern counterpart. A previous study of phase 3 of the CMIP (CMIP3) suggests that this trend is partially forced by anthropogenic sulfate aerosols. This analysis collectively confirms the partially forced trend for the CMIP5 and by anthropogenic aerosols. Like the CMIP3, the CMIP5 also simulates a reversal in the AITG trend in the late 1970s, which was attributed to a leveling offof the anthropogenic aerosol influence and increased influence of greenhouse gases in the late twentieth century. Two (of 25) CMIP5 models, however, systematically simulate a twentieth-century trend opposite to observed, leading to some uncertainty regarding the forced nature of the AITG trend. Here, the observed AITG also exhibits a pronounced multidecadal modulation on top of the trend, associated with the Atlantic multidecadal oscillation (AMO). Motivated by a recent suggestion that the AMO is a forced response to aerosols, the causes of this multidecadal behavior were also examined. A few of the CMIP5 models analyzed do produce multidecadal AITG variations that are correlated to the observed AMO-like variation, but only one, the Hadley Centre Global Environmental Model, version 2 (HadGEM2), systematically simulates AMO-like behavior with both the requisite amplitude and phase. The CMIP5 simulations thus point to a robust aerosol influence on the historical AITG trend but not to the AMO-like multidecadal behavior.},
doi = {10.1175/JCLI-D-12-00487.1},
journal = {Journal of Climate},
number = 21,
volume = 26,
place = {United States},
year = {2013},
month = {10}
}
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Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record
DOI:  10.1175/JCLI-D-12-00487.1
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Cited by: 14 works
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Figures / Tables:

FIG. 1 FIG. 1: The observed AITG index, defined as the SST difference between the north (5°–35°N, 0°–80°W) and south (5°–35°S, 60°W–20°E) tropical Atlantic, south minus north. Each line is from an observational SST dataset as denoted: Extended Reconstructed SST, version 3b (ERSST.v3b; Smith et al. 2008); Hadley Centre Sea Ice andmore » Sea Surface Temperature dataset (HadISST; Rayner et al. 2003); and Kaplan extended SST, version 2 (Kaplan et al. 1998). The dotted straight line is the linear least squares best-fit line to the average of the three curves.« less
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Works referencing / citing this record:

Simulation by CMIP5 models of the atlantic multidecadal oscillation and its climate impacts
journal, November 2016

Simulation by CMIP5 models of the atlantic multidecadal oscillation and its climate impacts
journal, November 2016

Anthropogenic sulfate aerosol and the southward shift of tropical precipitation in the late 20th century: AEROSOLS AND TROPICAL RAIN BELT SHIFTS
journal, June 2013

  • Hwang, Yen-Ting; Frierson, Dargan M. W.; Kang, Sarah M.
  • Geophysical Research Letters, Vol. 40, Issue 11
  • DOI: 10.1002/grl.50502

Seasonal predictability of the tropical Atlantic variability: northern tropical Atlantic pattern
journal, December 2018

The contrasting response of Hadley circulation to different meridional structure of sea surface temperature in CMIP5
journal, February 2018

  • Feng, Juan; Li, Jianping; Zhu, Jianlei
  • Theoretical and Applied Climatology, Vol. 135, Issue 1-2
  • DOI: 10.1007/s00704-018-2393-9

Multispecies Fisheries in the Lower Amazon River and Its Relationship with the Regional and Global Climate Variability
journal, June 2016

Decadal covariability of Atlantic SSTs and western Amazon dry-season hydroclimate in observations and CMIP5 simulations
text, January 2015

  • De Avila Fernandes, Katia; Giannini, Alessandra; Verchot, Louis
  • Columbia University
  • DOI: 10.7916/d88s4pbq
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