Abstract: The oceans provide essential services to our society, by regulating the climate, providing food and energy, ruling many of our economic activities. However, the marine ecosystem is more than ever impacted both by climate change and other human-induced pressures. As consequence there is a growing need to continuously monitor the oceans and to predict the marine weather and climate evolution.  Numerical modelling for marine and climate forecasting, time series analysis and algorithms to retrieve ocean geophysical parameter from space observation have been developed to answer these challenges.
Ocean currents are the most significant parameters for our study, significantly impacting the air-sea interaction, pollution and transport of ocean trace. We propose a global estimation of surface ocean currents from space by developing physical models and algorithm at the best spatial a temporal resolution. This is achieved by the inversion of the ocean heat conservation equation in upper ocean mixed layers applied to sea surface temperature satellite observation ad sea level altimeter measurements. The study evidenced that our synergistic approach can improve the present-day derivation of the surface currents up to 30% locally, allowing retrieval of both small scales and geostrophic features. In addition, by using Finite-Scale Lyapunov Exponents, the surface current fields produced have also been used for a rigorous, quantitative evaluation of satellite-based Lagrangian dispersion numerical trajectories.