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Title: Predictability and Decadal Variability of the North Atlantic Ocean State Evaluated from a Realistic Ocean Model

Abstract

This study investigates the excitation of decadal variability and predictability of the ocean climate state in the North Atlantic. Specifically, initial linear optimal perturbations (LOPs) in temperature and salinity that vary with depth, longitude, and latitude are computed, and the maximum impact on the ocean of these perturbations is evaluated in a realistic ocean general circulation model. The computations of the LOPs involve a maximization procedure based on Lagrange multipliers in a nonautonomous context. To assess the impact of these perturbations four different measures of the North Atlantic Ocean state are used: meridional volume and heat transports (MVT and MHT) and spatially averaged sea surface temperature (SST) and ocean heat content (OHC). It is shown that these metrics are dramatically different with regard to predictability. Whereas OHC and SST can be efficiently modified only by basin-scale anomalies, MVT and MHT are also strongly affected by smaller-scale perturbations. This suggests that instantaneous or even annual-mean values of MVT and MHT are less predictable than SST and OHC. Only when averaged over several decades do the former two metrics have predictability comparable to the latter two, which highlights the need for long-term observations of the Atlantic meridional overturning circulation in order tomore » accumulate climatically relevant data. This study also suggests that initial errors in ocean temperature of a few millikelvins, encompassing both the upper and deep ocean, can lead to ~0.1-K errors in the predictions of North Atlantic sea surface temperature on interannual time scales. This transient error growth peaks for SST and OHC after about 6 and 10 years, respectively, implying a potential predictability barrier.« less

Authors:
 [1];  [2]
  1. Univ. of Southampton (United Kingdom)
  2. Yale Univ., New Haven, CT (United States)
Publication Date:
Research Org.:
Yale Univ., New Haven, CT (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1537014
Grant/Contract Number:  
SC0016538
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Climate
Additional Journal Information:
Journal Volume: 30; Journal Issue: 2; Journal ID: ISSN 0894-8755
Publisher:
American Meteorological Society
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; Meteorology & Atmospheric Sciences

Citation Formats

Sévellec, Florian, and Fedorov, Alexey V. Predictability and Decadal Variability of the North Atlantic Ocean State Evaluated from a Realistic Ocean Model. United States: N. p., 2016. Web. doi:10.1175/jcli-d-16-0323.1.
Sévellec, Florian, & Fedorov, Alexey V. Predictability and Decadal Variability of the North Atlantic Ocean State Evaluated from a Realistic Ocean Model. United States. doi:10.1175/jcli-d-16-0323.1.
Sévellec, Florian, and Fedorov, Alexey V. Thu . "Predictability and Decadal Variability of the North Atlantic Ocean State Evaluated from a Realistic Ocean Model". United States. doi:10.1175/jcli-d-16-0323.1. https://www.osti.gov/servlets/purl/1537014.
@article{osti_1537014,
title = {Predictability and Decadal Variability of the North Atlantic Ocean State Evaluated from a Realistic Ocean Model},
author = {Sévellec, Florian and Fedorov, Alexey V.},
abstractNote = {This study investigates the excitation of decadal variability and predictability of the ocean climate state in the North Atlantic. Specifically, initial linear optimal perturbations (LOPs) in temperature and salinity that vary with depth, longitude, and latitude are computed, and the maximum impact on the ocean of these perturbations is evaluated in a realistic ocean general circulation model. The computations of the LOPs involve a maximization procedure based on Lagrange multipliers in a nonautonomous context. To assess the impact of these perturbations four different measures of the North Atlantic Ocean state are used: meridional volume and heat transports (MVT and MHT) and spatially averaged sea surface temperature (SST) and ocean heat content (OHC). It is shown that these metrics are dramatically different with regard to predictability. Whereas OHC and SST can be efficiently modified only by basin-scale anomalies, MVT and MHT are also strongly affected by smaller-scale perturbations. This suggests that instantaneous or even annual-mean values of MVT and MHT are less predictable than SST and OHC. Only when averaged over several decades do the former two metrics have predictability comparable to the latter two, which highlights the need for long-term observations of the Atlantic meridional overturning circulation in order to accumulate climatically relevant data. This study also suggests that initial errors in ocean temperature of a few millikelvins, encompassing both the upper and deep ocean, can lead to ~0.1-K errors in the predictions of North Atlantic sea surface temperature on interannual time scales. This transient error growth peaks for SST and OHC after about 6 and 10 years, respectively, implying a potential predictability barrier.},
doi = {10.1175/jcli-d-16-0323.1},
journal = {Journal of Climate},
number = 2,
volume = 30,
place = {United States},
year = {2016},
month = {12}
}

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Works referenced in this record:

Argo float data and metadata from Global Data Assembly Centre (Argo GDAC)
dataset, January 2018

  • Fumihiko, Akazawa; Turki, Alraddadi; Pascual, Ananda
  • DOI: 10.17882/42182

    Works referencing / citing this record:

    Argo float data and metadata from Global Data Assembly Centre (Argo GDAC)
    dataset, January 2018

    • Fumihiko, Akazawa; Turki, Alraddadi; Pascual, Ananda
    • DOI: 10.17882/42182

    Dynamical attribution of oceanic prediction uncertainty in the North Atlantic: application to the design of optimal monitoring systems
    journal, November 2017

    • Sévellec, Florian; Dijkstra, Henk A.; Drijfhout, Sybren S.
    • Climate Dynamics, Vol. 51, Issue 4
    • DOI: 10.1007/s00382-017-3969-2

    The impacts of oceanic deep temperature perturbations in the North Atlantic on decadal climate variability and predictability
    journal, December 2017