Turbulence homogène de l'océan pour les simulateurs climatiques

The CONTaCTS project goal was to improve parameterizations for ocean components of climate simulators, by distinguishing two components of ocean variability and studying their interactions: the predictable response of the “mean” flow to atmospheric forcing, and the chaotic intrinsic (eddy) component. Parameterization aims to capture the feedback of the latter on the former. We have combined 3 innovations for the analysis of several high-resolution primitive equation ocean simulations: (i) the thickness-weighted averaging (TWA) technique with (2) generalized buoyancy variables, applied in particular on (3) ensemble ocean simulations to capture local and instantaneous eddy/mean flow feedbacks. We have shown that traditional eddy parameterizations miss about half of these feedbacks. We have investigated these feedbacks from a cross-scale perspective using the aforementioned innovations and wavelet techniques, moving past usual assumptions of spatial homogeneity and temporal stationarity, and found that the spectral power law of ocean turbulence differs from traditional (idealized) predictions. Notable findings also include evidence of scale-dependent nonlocality in energy transfers, and of the randomness of eddy energy variability at large scale. The project also investigated small-scale mixing, air-sea submesoscale interactions, near-equatorial mixing, and contributed to the development of coupled models and of cloud-based software tools for large-scale model analysis. These results fed more than 24 publications to date proposing new views of ocean turbulence with the goal to enhance the fidelity of ocean dynamics in climate models.