Comparison of Ocean Tide Models with Satellite Altimeter Data.

Ocean tides are noise to those who wish to construct the ocean geoid using satellite altimeter data. Precise modeling of the ocean tides will help improve the geoid modeling accuracy. This report stuidies whether altimeter data itself can be used to assess various tide models. The Schwiderski Global Tide Model and the Kuo Pacific Ocean tide model were examined using SEASAT altimeter data in the Gulf of Alaska and South Pacific region. The NSWC Ocean Tide Model contains nine harmonic partial tides of the semi-diurnal, diurnal, and long-period species. The model includes effects of tide-generated terrestrial and oceanic mass perturbations. The Kuo model is a Pacific Ocean total tide model with earth tide corrections. The method employed here cannot as yet be used to study the long wavelength component of tides removed by the quadratic fits, and only height differences along near-repeat sub-satellite tracks can be studied; if the altimeter repeat ground tracks do not overlap exactly, geoidal variations can not be completely removed by simple subtraction. The precision of satellite altimetry also places a limit on the accuracy with which one can safely assess the error of a tide model. Within these limitations, the feasibility of using altimeter data to assess tide models has been successfully demonstrated. Keywords: Satellite altimetry.