Research projects

Ocean currents are a key element in the understanding of many oceanic and climate phenomena, and knowledge of them is fundamental for operational applications and navigation. Altimetric measures now make it possible to reconstruct the field of velocities on the ocean surface at spatial resolutions in the order of 100‑150 km, and with major errors in the localisation of currents when only two altimeters are available. Nevertheless, recent studies suggest that the velocities may also be estimated directly based on a single image of the sea surface temperature (SST) using an effective version of the surface quasi-geostrophic equations (eSQG). The application of this approach to the calculation of currents on a global scale requires certain adaptations and studies. Firstly, the oceans' cloud cover makes it necessary to use SST images obtained in the microwave spectrum, which means that its capacity to detect oceanic structures must be investigated, and that methodology must be adapted to these data. Secondly, it is necessary to adapt the eSQG approach so that it functions under a wider range of conditions. As a result of this, the main aim of this project is to develop and validate a methodology for the calculation of ocean currents on a global scale, based on the eSQG approach which combines SST observations using microwaves and altimeters, while researching the spatial variability and distribution of the currents observed.

During the first months of the project, work has commenced on measuring the capacity of current microwave sensors to identify mesoscale oceanic structures and thereby reconstruct velocities. For this, the reconstruction of oceanic currents was validated on the basis of quasi-geostrophic theory using SST measurements in the microwave range at a global level, taking the currents obtained using altimetry as the reference during the period when a maximum number of satellites were available (2002‑2005). Globally, the preliminary results show that reconstruction works better in areas that are close to the main maritime currents: the Gulf Stream, the circumpolar Antarctic current and the Kuroshio current.