A comparison of the annual cycle of sea level in coastal areas from gridded satellite altimetry and tide gauges

• Published in: Continental shelf research 2015-01, Vol.92, p.87-97
• Main Authors: Ruiz Etcheverry, L.A., Saraceno, M., Piola, A.R., Valladeau, G., Möller, O.O.
• Format: Article
• Language: English
• Subjects: Altimeters; Altimetry; Annual cycle; Coastal; Coastal area; Coastal currents; Density; Freshwater; Gages; Gauges; Marine; Sea level; Sea level anomaly; Tide gauges; Tides
• ISSN: 0278-4343; 1873-6955
• DOI: 10.1016/j.csr.2014.10.006

In this work we compare the annual component of sea level variations derived from 478 worldwide-distributed tide gauges with the annual component computed from a weekly gridded multi-mission altimeter product. Gridded altimetry data products allow for spatio-temporal analyses that are not possible based on along-track altimetry data. However, a precise validation is necessary in the coastal region before the gridded data can be used. Results of the comparisons show that root-mean-square differences (RMSD) between the two datasets are ≤2cm for 76.4% of the sites. RMSD higher than 4cm are caused by narrow coastal currents, nearby river outflows or other local phenomena. A methodology is proposed to assess the accuracy of the seasonal component of the gridded altimeter product in regions with a low density net of tide gauges. As a case study it is shown that the Southwestern Atlantic coast is a suitable region to study the spatio-temporal variability of the annual cycle of sea level since RMSD between annual altimetry data and in-situ data are lower than 2.1cm. •Validation of gridded altimetry data at annual scales in coastal areas.•The annual cycle is well represented by the altimeter for 76.4% of the cases.•Regions where RMSD are larger than 4cm are related with oceanographic processes.•Annual cycle in the Southwestern Atlantic coast is well represented by altimetry data.