Chaotic Variability of Ocean: Heat Content Climate-Relevant Features and Observational Implications
|Author(s)||Penduff Thierry1, Serazin Guillaume2, Leroux Stephanie3, Close Sally4, Molines Jean-Marc4, Barnier Bernard4, Bessieres Laurent5, Terray Laurent5, Maze Guillaume6|
|Affiliation(s)||1 : CNRS, IGE MEOM, UGA CS, F-40700 Grenoble, France.
2 : OMP, Lab Etud Geophys & Oceanog Spatiales, Toulouse, France.
3 : Ocean Next, Grenoble, France.
4 : Univ Grenoble Alpes, CNRS, IRD, Grenoble INP,Inst Geosci Environm, Grenoble, France.
5 : CNRS, CERFACS, CECI UMR 5318, Toulouse, France.
6 : Univ Brest, IFREMER, CNRS, IRD,Lab Oceanog Phys & Spatiale,IUEM, Plouzane, France.
|Source||Oceanography (1042-8275) (Oceanography Soc), 2018-06 , Vol. 31 , N. 2 , P. 63-71|
|WOS© Times Cited||25|
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.