Annual Cycle in Coastal Sea Level from Gridded Satellite Altimetry and Tide Gauges

SARACENO, M.; RUIZ ETCHEVERRY, L.R.; PIOLA, A. R.

Workshop; 7th COASTAL ALTIMETRY WORKSHOP; 2013

Sea level anomalies as retrieved from satellites are nowadays essential to describe and understand large to mesoscale process in the ocean, to climate-related studies and to operational oceanography. Despite altimeter data have been historically calibrated and validated mostly against coastal tide-gauges, their use in the coastal regions keeps limited. In this work we compare the annual component computed at 478 tide gauges worldwide distributed with the annual component extracted from gridded multi-mission altimeter products. Gridded altimetry products allow for spatio-temporal analyses that are not possible using along- track altimetry data. Root-mean-square differences (RMSD) between the two datasets show values lower than 3 cm for 84.3% of the sites. Regions with larger differences correspond to regions where narrow coastal currents, areas affected by strong river outflows or other local phenomena. The analysis suggests that in the coastal regions where the RMSD are small the analysis of the spatio- temporal variability of the annual component of the gridded altimetry product can be addressed.