Annular mode time scales in the intergovernmental panel on climate change fourth assessment report models

Edwin Gerber, L. M. Polvani, D. Ancukiewicz

Research output: Contribution to journalArticle

Abstract

The ability of climate models in the Intergovernmental Panel on Climate Change Fourth Assessment Report to capture the temporal structure of the annular modes is evaluated. The vertical structure and annual cycle of the variability is quantified by the e-folding time scale of the annular mode autocorrelation function. Models vaguely capture the qualitative features of the Northern and Southern Annular Modes: Northern Hemisphere time scales are shorter than those of the Southern Hemisphere and peak in boreal winter, while Southern Hemisphere time scales peak in austral spring and summer. Models, however, systematically overestimate the time scales, particularly in the Southern Hemisphere summer, where the multimodel ensemble average is twice that of reanalyses. Fluctuation-dissipation theory suggests that long time scales in models could be associated with increased sensitivity to anthropogenic forcing. Comparison of model pairs with similar forcings but different annular mode time scales provides a hint of a fluctuation-dissipation relationship.

Original languageEnglish (US)
Article numberL22707
JournalGeophysical Research Letters
Volume35
Issue number22
DOIs
StatePublished - Nov 28 2008

Fingerprint

Intergovernmental Panel on Climate Change
climate change
timescale
Southern Hemisphere
summer
dissipation
climate models
Northern Hemisphere
annual cycle
folding
autocorrelation
winter
climate modeling
cycles
sensitivity

ASJC Scopus subject areas

  • Earth and Planetary Sciences(all)
  • Geophysics

Cite this

Annular mode time scales in the intergovernmental panel on climate change fourth assessment report models. / Gerber, Edwin; Polvani, L. M.; Ancukiewicz, D.

In: Geophysical Research Letters, Vol. 35, No. 22, L22707, 28.11.2008.

Research output: Contribution to journalArticle

@article{ecdd82b8eac5492ab3e5ced3941affd2,
title = "Annular mode time scales in the intergovernmental panel on climate change fourth assessment report models",
abstract = "The ability of climate models in the Intergovernmental Panel on Climate Change Fourth Assessment Report to capture the temporal structure of the annular modes is evaluated. The vertical structure and annual cycle of the variability is quantified by the e-folding time scale of the annular mode autocorrelation function. Models vaguely capture the qualitative features of the Northern and Southern Annular Modes: Northern Hemisphere time scales are shorter than those of the Southern Hemisphere and peak in boreal winter, while Southern Hemisphere time scales peak in austral spring and summer. Models, however, systematically overestimate the time scales, particularly in the Southern Hemisphere summer, where the multimodel ensemble average is twice that of reanalyses. Fluctuation-dissipation theory suggests that long time scales in models could be associated with increased sensitivity to anthropogenic forcing. Comparison of model pairs with similar forcings but different annular mode time scales provides a hint of a fluctuation-dissipation relationship.",
author = "Edwin Gerber and Polvani, {L. M.} and D. Ancukiewicz",
year = "2008",
month = "11",
day = "28",
doi = "10.1029/2008GL035712",
language = "English (US)",
volume = "35",
journal = "Geophysical Research Letters",
issn = "0094-8276",
publisher = "American Geophysical Union",
number = "22",

}

TY - JOUR

T1 - Annular mode time scales in the intergovernmental panel on climate change fourth assessment report models

AU - Gerber, Edwin

AU - Polvani, L. M.

AU - Ancukiewicz, D.

PY - 2008/11/28

Y1 - 2008/11/28

N2 - The ability of climate models in the Intergovernmental Panel on Climate Change Fourth Assessment Report to capture the temporal structure of the annular modes is evaluated. The vertical structure and annual cycle of the variability is quantified by the e-folding time scale of the annular mode autocorrelation function. Models vaguely capture the qualitative features of the Northern and Southern Annular Modes: Northern Hemisphere time scales are shorter than those of the Southern Hemisphere and peak in boreal winter, while Southern Hemisphere time scales peak in austral spring and summer. Models, however, systematically overestimate the time scales, particularly in the Southern Hemisphere summer, where the multimodel ensemble average is twice that of reanalyses. Fluctuation-dissipation theory suggests that long time scales in models could be associated with increased sensitivity to anthropogenic forcing. Comparison of model pairs with similar forcings but different annular mode time scales provides a hint of a fluctuation-dissipation relationship.

AB - The ability of climate models in the Intergovernmental Panel on Climate Change Fourth Assessment Report to capture the temporal structure of the annular modes is evaluated. The vertical structure and annual cycle of the variability is quantified by the e-folding time scale of the annular mode autocorrelation function. Models vaguely capture the qualitative features of the Northern and Southern Annular Modes: Northern Hemisphere time scales are shorter than those of the Southern Hemisphere and peak in boreal winter, while Southern Hemisphere time scales peak in austral spring and summer. Models, however, systematically overestimate the time scales, particularly in the Southern Hemisphere summer, where the multimodel ensemble average is twice that of reanalyses. Fluctuation-dissipation theory suggests that long time scales in models could be associated with increased sensitivity to anthropogenic forcing. Comparison of model pairs with similar forcings but different annular mode time scales provides a hint of a fluctuation-dissipation relationship.

UR - http://www.scopus.com/inward/record.url?scp=60149106330&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=60149106330&partnerID=8YFLogxK

U2 - 10.1029/2008GL035712

DO - 10.1029/2008GL035712

M3 - Article

AN - SCOPUS:60149106330

VL - 35

JO - Geophysical Research Letters

JF - Geophysical Research Letters

SN - 0094-8276

IS - 22

M1 - L22707

ER -