Fine Resolution Altimetry Data for a Regional Application in the Bay of Biscay

Eddy properties in the Bay of Biscay are studied from 15 years of reprocessed along-track altimeter data using a wavelet-based analysis. Associated spatial scales vary from ∼60 km in the inner bay to 130 km offshore, with amplitudes also increasing offshore. These characteristics are not correctly represented in standard gridded products, which are too smooth. Compared to observed along-track data, geostrophic currents and eddy kinetic energy estimated from standard gridded maps are too weak by a factor of 33% and 50%, respectively. A new mapping approach is proposed to better resolve the local mesoscale variability. It uses the larger wavelengths of the standard gridded maps as a first guess and adds an increment based on the short scale signals of the along-track data. First results show coherent fine scale signals, consistent with the information provided by MODIS imagery.