Chaotic Variability of Ocean: Heat Content Climate-Relevant Features and Observational Implications
Global ocean models that admit mesoscale turbulence spontaneously generate a substantial interannual-to-multidecadal chaotic intrinsic variability in the absence of atmospheric forcing variability at these timescales. is phenomenon is substantially weaker in non-turbulent ocean models but provides a...
| Published in: | Oceanography |
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| Main Authors: | , , , , , , , , |
| Format: | Text |
| Language: | English |
| Published: |
Oceanography Soc
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| Subjects: | |
| Online Access: | https://doi.org/10.5670/oceanog.2018.210 https://archimer.ifremer.fr/doc/00448/55959/57440.pdf https://archimer.ifremer.fr/doc/00448/55959/ |
| Summary: | Global ocean models that admit mesoscale turbulence spontaneously generate a substantial interannual-to-multidecadal chaotic intrinsic variability in the absence of atmospheric forcing variability at these timescales. is phenomenon is substantially weaker in non-turbulent ocean models but provides a marked stochastic avor to the low-frequency variability in eddying ocean models, which are being cou- pled to the atmosphere for next-generation climate projections. In order to disentangle the atmospherically forced and intrinsic ocean variabilities, the OCCIPUT (OceaniC Chaos – ImPacts, strUcture, 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 ensem- ble 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 variabil- ity, raising new issues for the detection, attribution, and interpretation of oceanic heat variability and trends in the presence of mesoscale turbulence. |
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