Revisiting the CMIP5 Thermocline in the Equatorial Pacific and Atlantic Oceans

Abstract The thermocline is defined as the ocean layer for which the vertical thermal gradient is maximum. In the equatorial ocean, observations led to the use of the 20 °C isotherm depth (z20) as an estimate of the thermocline. This study compares z20 against the physical thermocline in the equator...

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Main Authors: A. Castaño‐Tierno, E. Mohino, B. Rodríguez‐Fonseca, T. Losada
Format: Article
Language:English
Published: Wiley 2018-12-01
Series:Geophysical Research Letters
Subjects:
Online Access:https://doi.org/10.1029/2018GL079847
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author A. Castaño‐Tierno
E. Mohino
B. Rodríguez‐Fonseca
T. Losada
author_facet A. Castaño‐Tierno
E. Mohino
B. Rodríguez‐Fonseca
T. Losada
author_sort A. Castaño‐Tierno
collection DOAJ
description Abstract The thermocline is defined as the ocean layer for which the vertical thermal gradient is maximum. In the equatorial ocean, observations led to the use of the 20 °C isotherm depth (z20) as an estimate of the thermocline. This study compares z20 against the physical thermocline in the equatorial Atlantic and Pacific Oceans, using Simple Ocean Data Assimilation reanalysis and fifth phase of the Coupled Model Intercomparison Project preindustrial control simulations. Our results show that z20 is systematically deeper and flatter than the thermocline and does not respond correctly to surface wind stress variations. It is also shown that the annual cycle of z20 is much weaker than that of the physical thermocline. This happens in both equatorial basins and indicates that z20 does not react to the same mechanisms as the thermocline. This could have important consequences in the assessment of air‐sea coupling in current general circulation models and bias reduction strategies.
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institution DOAJ
issn 0094-8276
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publishDate 2018-12-01
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series Geophysical Research Letters
spelling doaj-art-77a5ecc0873b4b6c9be181016cc540db2025-08-20T03:09:42ZengWileyGeophysical Research Letters0094-82761944-80072018-12-01452312,96312,97110.1029/2018GL079847Revisiting the CMIP5 Thermocline in the Equatorial Pacific and Atlantic OceansA. Castaño‐Tierno0E. Mohino1B. Rodríguez‐Fonseca2T. Losada3Department of Physics of the Earth and Astrophysics Universidad Complutense de Madrid Madrid SpainDepartment of Physics of the Earth and Astrophysics Universidad Complutense de Madrid Madrid SpainDepartment of Physics of the Earth and Astrophysics Universidad Complutense de Madrid Madrid SpainDepartment of Physics of the Earth and Astrophysics Universidad Complutense de Madrid Madrid SpainAbstract The thermocline is defined as the ocean layer for which the vertical thermal gradient is maximum. In the equatorial ocean, observations led to the use of the 20 °C isotherm depth (z20) as an estimate of the thermocline. This study compares z20 against the physical thermocline in the equatorial Atlantic and Pacific Oceans, using Simple Ocean Data Assimilation reanalysis and fifth phase of the Coupled Model Intercomparison Project preindustrial control simulations. Our results show that z20 is systematically deeper and flatter than the thermocline and does not respond correctly to surface wind stress variations. It is also shown that the annual cycle of z20 is much weaker than that of the physical thermocline. This happens in both equatorial basins and indicates that z20 does not react to the same mechanisms as the thermocline. This could have important consequences in the assessment of air‐sea coupling in current general circulation models and bias reduction strategies.https://doi.org/10.1029/2018GL079847thermoclinemodel biasesequatorial oceanKuroshio intrusionnorthern South China Sea
spellingShingle A. Castaño‐Tierno
E. Mohino
B. Rodríguez‐Fonseca
T. Losada
Revisiting the CMIP5 Thermocline in the Equatorial Pacific and Atlantic Oceans
Geophysical Research Letters
thermocline
model biases
equatorial ocean
Kuroshio intrusion
northern South China Sea
title Revisiting the CMIP5 Thermocline in the Equatorial Pacific and Atlantic Oceans
title_full Revisiting the CMIP5 Thermocline in the Equatorial Pacific and Atlantic Oceans
title_fullStr Revisiting the CMIP5 Thermocline in the Equatorial Pacific and Atlantic Oceans
title_full_unstemmed Revisiting the CMIP5 Thermocline in the Equatorial Pacific and Atlantic Oceans
title_short Revisiting the CMIP5 Thermocline in the Equatorial Pacific and Atlantic Oceans
title_sort revisiting the cmip5 thermocline in the equatorial pacific and atlantic oceans
topic thermocline
model biases
equatorial ocean
Kuroshio intrusion
northern South China Sea
url https://doi.org/10.1029/2018GL079847
work_keys_str_mv AT acastanotierno revisitingthecmip5thermoclineintheequatorialpacificandatlanticoceans
AT emohino revisitingthecmip5thermoclineintheequatorialpacificandatlanticoceans
AT brodriguezfonseca revisitingthecmip5thermoclineintheequatorialpacificandatlanticoceans
AT tlosada revisitingthecmip5thermoclineintheequatorialpacificandatlanticoceans