Spatial and temporal agreement in climate model simulations of the Interdecadal Pacific Oscillation

Henley, Benjamin J. and Meehl, Gerald and Power, Scott B. and Folland, Chris K. and King, Andrew D. and Brown, Jaclyn N. and Karoly, David J. and Delage, Francois and Gallant, Ailie J. E. and Freund, Mandy and Neukom, Raphael (2017) Spatial and temporal agreement in climate model simulations of the Interdecadal Pacific Oscillation. Environmental Research Letters, 12 (4).

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Accelerated warming and hiatus periods in the long-term rise of Global Mean Surface Temperature (GMST) have, in recent decades, been associated with the Interdecadal Pacific Oscillation (IPO). Critically, decadal climate prediction relies on the skill of state-of-the-art
climate models to reliably represent these low-frequency climate variations. We undertake a systematic evaluation of the simulation of the IPO in the suite of Coupled Model
Intercomparison Project 5 (CMIP5) models. We track the IPO in pre-industrial (control) and allforcings (historical) experiments using the IPO tripole index (TPI). The TPI is explicitly aligned with the observed spatial pattern of the IPO, and circumvents assumptions about the nature of
global warming. We find that many models underestimate the ratio of decadal-to-total variance in sea surface temperatures (SSTs). However, the basin-wide spatial pattern of positive and negative phases of the IPO are simulated reasonably well, with spatial pattern correlation
coefficients between observations and models spanning the range 0.4–0.8. Deficiencies are mainly in the extratropical Pacific. Models that better capture the spatial pattern of the IPO also tend to more realistically simulate the ratio of decadal to total variance. Of the 13% of model centuries
that have a fractional bias in the decadal-to-total TPI variance of 0.2 or less, 84% also have a spatial pattern correlation coefficient with the observed pattern exceeding 0.5. This result is highly consistent across both IPO positive and negative phases. This is evidence that the IPO is related to one or more inherent dynamical mechanisms of the climate system.

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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Original content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
Faculty / Department / School: No Faculty
Date Deposited: 04 Apr 2017 06:25
Last Modified: 18 Apr 2018 00:18
Uncontrolled Keywords: Interdecadal Pacific Oscillation, Pacific Decadal Oscillation, Pacific Decadal Variability, IPO, PDO, CMIP5, model evaluation
Fields of Research : 04 Earth Sciences > 0401 Atmospheric Sciences > 040104 Climate Change Processes
Identification Number or DOI: 10.1088/1748-9326/aa5cc8

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