Chaotic Variability of Ocean Heat Content: Climate-Relevant Features and Observational Implications
Global ocean models that admit mesoscale turbulence spontaneously generate interannual-to-multidecadal chaotic intrinsic variability in the absence of atmospheric forcing variability at these timescales. This phenomenon is substantially weaker in non-turbulent ocean models but provides a marked stoc...
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doaj-a88a04d0153b4f1aade8b0fa70b828d52020-11-25T01:32:32ZengThe Oceanography SocietyOceanography1042-82752018-06-01312637110.5670/oceanog.2018.210Chaotic Variability of Ocean Heat Content: Climate-Relevant Features and Observational ImplicationsThierry Penduff 0Guillaume Sérazin 1Stéphanie Leroux2Sally Close 3Jean-Marc Molines 4Bernard Barnier 5Laurent Bessières6Laurent Terray 7Guillaume Maze 8CNRSLaboratoire d'Études en Géophysique et Océanographie Spatiales, OMPOcean NextUniversité Grenoble AlpesUniversité Grenoble AlpesUniversité Grenoble AlpesCNRS/CERFACSCNRS/CERFACSIfremer, Université de BrestGlobal ocean models that admit mesoscale turbulence spontaneously generate interannual-to-multidecadal chaotic intrinsic variability in the absence of atmospheric forcing variability at these timescales. This phenomenon is substantially weaker in non-turbulent ocean models but provides a marked stochastic flavor to the low-frequency variability in eddying ocean models, which are being coupled to the atmosphere for next-generation climate projections. In order to disentangle the atmospherically forced and intrinsic ocean variabilities, the OCCIPUT (Oceanic Chaos – Impacts, Structures, Predictability) project performed a long (1960–2015), large ensemble (50 members) of global ocean/sea ice 1/4° simulations driven by the same atmospheric reanalysis, but with perturbed initial conditions. Subsequent ensemble statistics show that the ocean variability can be seen as a broadband "noise," with characteristic scales reaching multiple decades and basin sizes, locally modulated by the atmospheric variability. In several mid-latitude regions, chaotic processes have more impact than atmospheric variability on both the low-frequency variability and the long-term trends of regional ocean heat content. Consequently, certain climate-relevant oceanic signals cannot be unambiguously attributed to atmospheric variability, raising new issues for the detection, attribution, and interpretation of oceanic heat variability and trends in the presence of mesoscale turbulence.https://doi.org/10.5670/oceanog.2018.210ocean modelsmesoscale turbulenceocean heat |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Thierry Penduff Guillaume Sérazin Stéphanie Leroux Sally Close Jean-Marc Molines Bernard Barnier Laurent Bessières Laurent Terray Guillaume Maze |
spellingShingle |
Thierry Penduff Guillaume Sérazin Stéphanie Leroux Sally Close Jean-Marc Molines Bernard Barnier Laurent Bessières Laurent Terray Guillaume Maze Chaotic Variability of Ocean Heat Content: Climate-Relevant Features and Observational Implications Oceanography ocean models mesoscale turbulence ocean heat |
author_facet |
Thierry Penduff Guillaume Sérazin Stéphanie Leroux Sally Close Jean-Marc Molines Bernard Barnier Laurent Bessières Laurent Terray Guillaume Maze |
author_sort |
Thierry Penduff |
title |
Chaotic Variability of Ocean Heat Content: Climate-Relevant Features and Observational Implications |
title_short |
Chaotic Variability of Ocean Heat Content: Climate-Relevant Features and Observational Implications |
title_full |
Chaotic Variability of Ocean Heat Content: Climate-Relevant Features and Observational Implications |
title_fullStr |
Chaotic Variability of Ocean Heat Content: Climate-Relevant Features and Observational Implications |
title_full_unstemmed |
Chaotic Variability of Ocean Heat Content: Climate-Relevant Features and Observational Implications |
title_sort |
chaotic variability of ocean heat content: climate-relevant features and observational implications |
publisher |
The Oceanography Society |
series |
Oceanography |
issn |
1042-8275 |
publishDate |
2018-06-01 |
description |
Global ocean models that admit mesoscale turbulence spontaneously generate interannual-to-multidecadal chaotic intrinsic variability in the absence of atmospheric forcing variability at these timescales. This phenomenon is substantially weaker in non-turbulent ocean models but provides a marked stochastic flavor to the low-frequency variability in eddying ocean models, which are being coupled to the atmosphere for next-generation climate projections. In order to disentangle the atmospherically forced and intrinsic ocean variabilities, the OCCIPUT (Oceanic Chaos – Impacts, Structures, Predictability) project performed a long (1960–2015), large ensemble (50 members) of global ocean/sea ice 1/4° simulations driven by the same atmospheric reanalysis, but with perturbed initial conditions. Subsequent ensemble statistics show that the ocean variability can be seen as a broadband "noise," with characteristic scales reaching multiple decades and basin sizes, locally modulated by the atmospheric variability. In several mid-latitude regions, chaotic processes have more impact than atmospheric variability on both the low-frequency variability and the long-term trends of regional ocean heat content. Consequently, certain climate-relevant oceanic signals cannot be unambiguously attributed to atmospheric variability, raising new issues for the detection, attribution, and interpretation of oceanic heat variability and trends in the presence of mesoscale turbulence. |
topic |
ocean models mesoscale turbulence ocean heat |
url |
https://doi.org/10.5670/oceanog.2018.210 |
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