The ocean is an important part of the earth climate’s system, contributing to transport the excess of heat from the equator to the northern latitudes. The air-sea interaction and most of the biological productivity occur in the upper ocean. Despite that, the precise physical processes that govern the ocean surface circulation are still not well defined. The objective of this proposal is to advance in the understanding of the physical processes that govern the upper-ocean circulation of the oceanic subtropical gyres, by focusing in two complementary systems, the Kuroshio Current (outgoing phase) and the Canary Current (return phase), the western and eastern components of the north Pacific and Atlantic subtropical gyres. The particular scientific objectives will be approached by way of an innovative methodology that combines surface lagrangian velocities and satellite data. Surface lagrangian observations provide now a days the most accurate and feasible representation of surface ocean circulation at open and coastal ocean. This methodology, recently developed by the outgoing research group, will permit to obtain the first detailed analysis of the actual surface circulation patterns of both areas. The outgoing phase will be carried in one of the world’s most prestigious ocean research organizations, the Scripps Institution of Oceanography (USA). Data analyses and evaluation of results will be jointly carried out with scientist with wide expertise in the proposed scientific and methodological topics, and in the framework of current multidisciplinary experiments of the outgoing host group. The return phase, in one of the leading European centre for ocean research, the Instituto Español de Oceanografia (Spain), will permit to capitalize the experience and training acquired, by addressing the return scientific objectives. The fellowship will permit to bring back to Europe a unique knowledge in the use of surface lagrangian data to understand and monitor the upper ocean.