Section: New Results

Multiplicative cascades in real/synthetic oceanographic signals: application to the evaluation of ocean dynamics

Participants : Hussein Yahia, Oriol Pont, Joel Sudre, Véronique Garçon, Claire Pottier [CNES] , Antonio Turiel, Christine Provost.

This work is performed during the final year of the HIRESUBCOLOR contract with CNES/NASA. From a fundamental point of view, significant advances have been worked out in the application of complex systems methods for the derivation of new methods for computing ocean dynamics at high spatial resolution (high resolution Sea Surface Temperature, pixel size: 4 x 4 kms). No temporal information is used. Instead, the norms and orientations of low resolution vector fields derived from altimetry and scatterometers are propagated along the scales of turbulent signals. This year, specific study on the propagation of the norm of the vector field has been conducted, resulting in the complete mapping (norm and orientation) of ocean dynamics at the high resolution of Sea Surface Temperature data. Validation is performed by comparison with the output of the ROMS 3D simulation model, with excellent results, and buoy validation is under way. H. Yahia has been invited to the AGU (American Geophysical Union) Fall meeting in San Francisco to make a presentation of HIRESUBCOLOR results (December 5-9 2011) and also to the EGU meeting to be held in Vienna in 2012. In 2011 the complete method for the determination of ocean dynamics has been finalized and it includes:

• the determination of both norm and orientation of the vector fields,

• the propagation along the scale of both geostrophic and ageostrophic dynamics.

These methods are generic, and can be applied to the determination of high resolution information for ocean/atmosphere interaction. For that matter, the Oceanflux proposal has been submitted and accepted, starting November 1, 2011, and a new proposal called MULTICARO will be submitted to CNES-OSTST. Related publications: [28] , [21] .