(c) LGGE

The facts & the project

Because of the importance of its role in the Earth’s climate system, oceanic circulation is the subject of a large number of simulations. These have already helped reveal ce-tain of the characteristics of oceanic turbulence under the dominant influence of the rotation of the planet.

Using the NEMO code based NATL60 simulation, Bernard Barnier, Director of research at CNRS, and its MEOM (Modélisation des Ecoulements Océa-niques Multi-Echelles) team at the LGGE (Laboratoire de Glaciologie et Géophysique de l’Environnement), have taken a further step forward!

With eight weeks on Occigen, and an allocation of 17 million hours, it piloted the very first simulation ever created of the oceanic circulation in the North Atlantic on a kilometre scale and taking into account the complexity of under-sea hills and elevations (with a resolution of one metre at the surface, to 50 metres in the deepest depressions) as well as the enormous variability of surface atmospheric conditions.

The results

Enough to make a novice’s head spin but bring great joy to scientists who, thanks to these truly exceptional simulations - which represent a factor 30 improvement on the existing state-of-the-art in oceanography - have revealed a “new”, never beforeseen, ocean.

This ocean is an extraordinary entanglement, in three dimensions, of minute scale circulation structures, combining waves and currents, distributed in a highly heterogeneous way throught he basin and subject to a very strong seasonality.

These extremely unsteady movements help explain the difficulties in linking spatial observations of the surface and in-situ measurements.

The data gathered during the analysis (tens of terabytes) will act as a reference for the joint French-US SWOT (Surface Water and Ocean Topography) space mission that will be launched in 2020.

Significant advances are to be hoped for in our understanding of the interactions between the various scale oceanic movements.