Coastal and mesoscale dynamics characterization using altimetry and gliders: A case study in the Balearic Sea

Dynamics along the continental slopes are difficult to observe given the wide spectrum of temporal and spatial variability of physical processes which occur (coastal currents, meanders, eddies, etc.). Studying such complex dynamics requires the development of synergic approaches that use integrated observing systems. In this context, we present the results of an observational program conducted in the Balearic Sea combining coastal gliders and altimetry. The objectives of this experiment are to study regional dynamics using new technologies, such as gliders, in synergy with satellite altimetry and to investigate the limitations and potential improvement to altimetric data sets in the coastal zone. In this regard, new methodologies have been developed to compute consistent altimetric and glider velocities, and a novel technique to estimate absolute glider velocities, combining surface glider geostrophic velocities with integrated currents estimated from the glider GPS positioning, has been applied. In addition, the altimetric velocity computation has been improved, especially in the coastal zone, using high-frequency along-track sampling associated with new filtering and editing techniques. This approach proves efficient for homogenizing the physical contents of altimetry and glider surface currents (percentage of standard deviation explained is >40) and characterizing regional dynamics in the Balearic Sea through a combined analysis of a high-resolution observing system, such as the appearance of anomalous intense mesoscale features missing in the classical circulation scheme of the Balearic Sea.