A Global Ocean Tide Model From TOPEX/POSEIDON Altimetry: GOT99.2

TLDR

The Goddard Ocean Tide model GOT99.2 provides new amplitudes and phases for global oceanic tides, derived from over six years of TOPEX/POSEIDON satellite altimetry. The report details altimetry data processing and delivers comprehensive global cotidal charts and tabulated low‑degree spherical harmonic coefficients for major short‑period tides, aiding geodetic and geophysical applications. The solution incorporates prior hydrodynamic models and the global finite‑element model FES94.1, and generates derived tidal charts—loading deformation, gravimetric, and current velocity—as well as low‑degree spherical harmonic coefficients. Comparison with deep‑ocean tide‑gauge measurements shows the new tidal solution improves upon previous global models, achieving sub‑1.5 cm accuracy for the main semidiurnal lunar constituent M2 in deep water.

Abstract

Goddard Ocean Tide model GOT99.2 is a new solution for the amplitudes and phases of the global oceanic tides, based on over six years of sea-surface height measurements by the TOPEX/POSEIDON satellite altimeter. Comparison with deep-ocean tide-gauge measurements show that this new tidal solution is an improvement over previous global models, with accuracies for the main semidiurnal lunar constituent M2 now below 1.5 cm (deep water only). The new solution benefits from use of prior hydrodynamic models, several in shallow and inland seas as well as the global finite-element model FES94.1. This report describes some of the data processing details involved in handling the altimetry, and it provides a comprehensive set of global cotidal charts of the resulting solutions. Various derived tidal charts are also provided, including tidal loading deformation charts, tidal gravimetric charts, and tidal current velocity (or transport) charts. Finally, low-degree spherical harmonic coefficients are computed by numerical quadrature and are tabulated for the major short-period tides; these are useful for a variety of geodetic and geophysical purposes, especially in combination with similar estimates from satellite laser ranging.