CONICET | Buscador de Institutos y Recursos Humanos

The performance of gridded and along-track satellite altimetry data in the Argentinean continental shelf is evaluated with the help of year-long in situ time series of pressure, temperature and salinity data obtained at the sea bottom, and direction and speed of currents in the whole water column obtained in two different sites under Jason track #26.In situ SLA is reconstructed from bottom pressure measurements. The largest correlation coefficient and lowest RMSD between in situ SLA and 1Hz along-track SLA (0.58, 95% confidence level and 8.6cm) are obtained when a 15-day low-pass filter is applied to in situ data. Similar results are obtained with gridded altimetry data. When comparing currents, the highest correlation (0.5, 95% confidence level) and lowest RMSD (8cm) is obtained between 15-day low-pass filtered in situ data obtained at 8m depth and gridded altimetry data that included the Ekman component. The same results are obtained when considering the across-track velocities obtained from along-track data produced by CTOH that does not includes Ekman velocities.To understand the relative poor performance of the satellite altimetry data in the region we analyzed the correlation with sea level pressure (SLP) as estimated from different sources. NCEP SLP variability showed high coherence with the in situ surface currents at all depths, suggesting that the dynamics of the region is dominated by atmospheric forcing. Results also show that currents are better represented by satellite data (that includes he Ekman component) when the wind speed is lower than 0.8m.s-1 (RMSD 10cm.s-1). These results suggest that ageostrophic components might play a significant role in the Patagonian continental shelf, and therefore should be considered to compare with geostrophic currents obtained by satellite altimetry data.