In the context of global change and ocean response to climatic and anthropogenic forcing, it is critical to improve our understanding of biologically mediated carbon fluxes and to reduce the uncertainties in their estimates. At the root of much of the present uncertainty in carbon budget is the scarcity of data. Based on state-of-the-art remotely-operated techniques of observation (profiling floats and satellite) and bio-optical modelling, REMOCEAN aims at addressing the causes of variability in the so-called biological oceanic pump in key oceanic areas: (1) the North Atlantic (especially Labrador Sea, Irminger Sea, Iceland basin), which despite representing only 1.4% of the ocean s area, accounts for about 20% of the global ocean carbon sink; (2) the sub-tropical gyres of the Atlantic and Pacific for which, although they represent ~ 60% of the ocean surface, the contribution to oceanic carbon cycle is still a matter of debate. The scientific objectives of REMOCEAN will be implemented along four main activities. " Development of profiling floats to measure oceanic variables essential for the characterization of phytoplankton dynamics and related carbon fluxes. " Deployment of these floats in the four sub-tropical gyres of the Pacific and Atlantic Oceans and in the North Atlantic to conduct a totally automated investigation of biogeochemical cycles in these areas over a continuum of temporal scale and over a period of 3-4 years. " Development of parameterisations linking surface biogeochemical properties to their vertical distribution in the ocean interior, and ultimately development of 3D fields of these properties by combining float and satellite data. " Estimation of carbon fluxes by combining these fields with bio-optical modelling including retrospective analyses thanks to satellite data archives. A large part (~2 M¬) of the requested budget will be dedicated to the development, the acquisition and the functioning of the floats.