Evaluation of Ocean Tide Models Used for Jason-2 Altimetry Corrections

Abstract

It has been more than a decade since the last comprehensive accuracy assessment of global ocean tide models. Here, we conduct an evaluation of the barotropic ocean tide corrections, which were computed using FES2004 and GOT00.2, and other models on the Jason-2 altimetry Geophysical Data Record (GDR), with a focus on selected coastal regions with energetic ocean dynamics. We compared nine historical and contemporary ocean tide models with pelagic tidal constants and with multiple satellite altimetry mission (T/P, ERS-1/-2, Envisat, GFO, Jason-1/-2) sea level anomalies using variance reduction studies. All accuracy assessment methods show consistent results. We conclude that all the contemporary ocean tide models evaluated have similar performance in the selected coastal regions. However, their accuracies are region-dependent and overall are significantly worse than those in the deep-ocean, which are at the 2–3 cm RMS (root-mean-square) level. The Gulf of Mexico and Northwest Atlantic regions present the least reduction of altimetry sea surface height variability after ocean tides are removed, primarily because of large oceanic variability associated with loop currents in the Gulf of Mexico and the Gulf Stream in the Northwest Atlantic.

Keywords:

• Ocean tides
• satellite altimetry
• coastal regions

Acknowledgments

This research is partially support by grants from NASA's Physical Oceanography Program under the Ocean Surface Topography Mission (OSTM) projects (JPL 1356532, and University of Colorado 154-5322), from Hong Kong Research Grants Council (Grant No. PolyU 5184/06E/B-Q02D), and from the Canadian Space Agency. TOPEX/Poseidon, Jason-1 and Jason-2 altimetry data products are from NASA and CNES, via JPL PODACC and CNES Aviso. ERS-1/-2 and Envisat altimetry data are from ESA/ESRIN, and GFO altimetry data are provided by the U.S. Navy, via NOAA's Laboratory for Satellite Altimetry. This research was carried out, in part, by the Jet Propulsion Laboratory (JPL), California Institute of Technology, under contract with the National Aeronautics and Space Administration (NASA). We thank the two anonymous reviewers for their constructive comments which resulted in an improved manuscript. We thank the ocean tidal modelers for providing their models, and Richard Ray for providing pelagic and coastal gauge tidal constants.