Influence of recent stratification changes on ENSO stability in a conceptual model of the equatorial pacific

Sulian Thual, Boris Dewitte, Soon Il An, Serena Illig, Nadia Ayoub

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

Changes in the mean circulation of the equatorial Pacific Ocean partly control the strong decadal modulation of El Niño-Southern Oscillation (ENSO). This relationship is considered from the linear stability of a conceptual recharge/discharge model with parameters tuned from the observed mean state. Whereas decadal changes in the mean thermocline depth alone are usually considered in conceptual ENSO models, here focus is given to decadal changes in the mean stratification of the entire upper ocean (e.g., the mean thermocline depth, intensity, and thickness). Those stratification changes modify the projection of wind stress forcing momentum onto the gravest ocean baroclinic modes. Their influence on the simulated frequency and growth rate is comparable in intensity to the one of usual thermodynamic and atmospheric feedbacks, while they have here a secondary effect on the spatial structure and propagation of SST anomalies. This sensitivity is evidenced in particular for the climate shift of the 1970s in the Simple Ocean Data Assimilation (SODA) dataset, as well as in a preindustrial simulation of the Geophysical Fluid Dynamics Laboratory (GFDL) model showing stratification changes similar to the ones after 2000. Despite limitations of the linear stability approach, conclusions on the sensitivity to stratification may be extended to interpret the modulation and diversity of ENSO in observations and in general circulation models.

Original languageEnglish
Pages (from-to)4790-4802
Number of pages13
JournalJournal of Climate
Volume26
Issue number13
DOIs
Publication statusPublished - 2013 Jul 1

Fingerprint

Southern Oscillation
stratification
thermocline
ocean
baroclinic mode
fluid dynamics
upper ocean
wind stress
data assimilation
general circulation model
recharge
momentum
sea surface temperature
thermodynamics
anomaly
climate
simulation

All Science Journal Classification (ASJC) codes

  • Atmospheric Science

Cite this

Thual, Sulian ; Dewitte, Boris ; An, Soon Il ; Illig, Serena ; Ayoub, Nadia. / Influence of recent stratification changes on ENSO stability in a conceptual model of the equatorial pacific. In: Journal of Climate. 2013 ; Vol. 26, No. 13. pp. 4790-4802.
@article{bc821744d3a043adae4f95f68150266f,
title = "Influence of recent stratification changes on ENSO stability in a conceptual model of the equatorial pacific",
abstract = "Changes in the mean circulation of the equatorial Pacific Ocean partly control the strong decadal modulation of El Ni{\~n}o-Southern Oscillation (ENSO). This relationship is considered from the linear stability of a conceptual recharge/discharge model with parameters tuned from the observed mean state. Whereas decadal changes in the mean thermocline depth alone are usually considered in conceptual ENSO models, here focus is given to decadal changes in the mean stratification of the entire upper ocean (e.g., the mean thermocline depth, intensity, and thickness). Those stratification changes modify the projection of wind stress forcing momentum onto the gravest ocean baroclinic modes. Their influence on the simulated frequency and growth rate is comparable in intensity to the one of usual thermodynamic and atmospheric feedbacks, while they have here a secondary effect on the spatial structure and propagation of SST anomalies. This sensitivity is evidenced in particular for the climate shift of the 1970s in the Simple Ocean Data Assimilation (SODA) dataset, as well as in a preindustrial simulation of the Geophysical Fluid Dynamics Laboratory (GFDL) model showing stratification changes similar to the ones after 2000. Despite limitations of the linear stability approach, conclusions on the sensitivity to stratification may be extended to interpret the modulation and diversity of ENSO in observations and in general circulation models.",
author = "Sulian Thual and Boris Dewitte and An, {Soon Il} and Serena Illig and Nadia Ayoub",
year = "2013",
month = "7",
day = "1",
doi = "10.1175/JCLI-D-12-00363.1",
language = "English",
volume = "26",
pages = "4790--4802",
journal = "Journal of Climate",
issn = "0894-8755",
publisher = "American Meteorological Society",
number = "13",

}

Influence of recent stratification changes on ENSO stability in a conceptual model of the equatorial pacific. / Thual, Sulian; Dewitte, Boris; An, Soon Il; Illig, Serena; Ayoub, Nadia.

In: Journal of Climate, Vol. 26, No. 13, 01.07.2013, p. 4790-4802.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Influence of recent stratification changes on ENSO stability in a conceptual model of the equatorial pacific

AU - Thual, Sulian

AU - Dewitte, Boris

AU - An, Soon Il

AU - Illig, Serena

AU - Ayoub, Nadia

PY - 2013/7/1

Y1 - 2013/7/1

N2 - Changes in the mean circulation of the equatorial Pacific Ocean partly control the strong decadal modulation of El Niño-Southern Oscillation (ENSO). This relationship is considered from the linear stability of a conceptual recharge/discharge model with parameters tuned from the observed mean state. Whereas decadal changes in the mean thermocline depth alone are usually considered in conceptual ENSO models, here focus is given to decadal changes in the mean stratification of the entire upper ocean (e.g., the mean thermocline depth, intensity, and thickness). Those stratification changes modify the projection of wind stress forcing momentum onto the gravest ocean baroclinic modes. Their influence on the simulated frequency and growth rate is comparable in intensity to the one of usual thermodynamic and atmospheric feedbacks, while they have here a secondary effect on the spatial structure and propagation of SST anomalies. This sensitivity is evidenced in particular for the climate shift of the 1970s in the Simple Ocean Data Assimilation (SODA) dataset, as well as in a preindustrial simulation of the Geophysical Fluid Dynamics Laboratory (GFDL) model showing stratification changes similar to the ones after 2000. Despite limitations of the linear stability approach, conclusions on the sensitivity to stratification may be extended to interpret the modulation and diversity of ENSO in observations and in general circulation models.

AB - Changes in the mean circulation of the equatorial Pacific Ocean partly control the strong decadal modulation of El Niño-Southern Oscillation (ENSO). This relationship is considered from the linear stability of a conceptual recharge/discharge model with parameters tuned from the observed mean state. Whereas decadal changes in the mean thermocline depth alone are usually considered in conceptual ENSO models, here focus is given to decadal changes in the mean stratification of the entire upper ocean (e.g., the mean thermocline depth, intensity, and thickness). Those stratification changes modify the projection of wind stress forcing momentum onto the gravest ocean baroclinic modes. Their influence on the simulated frequency and growth rate is comparable in intensity to the one of usual thermodynamic and atmospheric feedbacks, while they have here a secondary effect on the spatial structure and propagation of SST anomalies. This sensitivity is evidenced in particular for the climate shift of the 1970s in the Simple Ocean Data Assimilation (SODA) dataset, as well as in a preindustrial simulation of the Geophysical Fluid Dynamics Laboratory (GFDL) model showing stratification changes similar to the ones after 2000. Despite limitations of the linear stability approach, conclusions on the sensitivity to stratification may be extended to interpret the modulation and diversity of ENSO in observations and in general circulation models.

UR - http://www.scopus.com/inward/record.url?scp=84880687804&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84880687804&partnerID=8YFLogxK

U2 - 10.1175/JCLI-D-12-00363.1

DO - 10.1175/JCLI-D-12-00363.1

M3 - Article

AN - SCOPUS:84880687804

VL - 26

SP - 4790

EP - 4802

JO - Journal of Climate

JF - Journal of Climate

SN - 0894-8755

IS - 13

ER -