Tidal estimation in the Atlantic and Indian Oceans

Abstract

An estimation technique has been developed to extrapolate tidal amplitudes and phases over entire ocean basins using existing gauge data and the altimetric measurements which are now beginning to be provided by satellite oceanography. The technique was tested previously in the Lake Superior basin by Sanchez et al. (1985). The method has now been developed and applied in the Atlantic‐Indian ocean basins using a 6° × 6° grid to test its essential features.

The functions used in the interpolation are the eigenfunctions of the velocity potential (Proudman functions), which are computed numerically from a knowledge of the basin's bottom topography, the horizontal plan form, and the necessary boundary conditions. These functions are characteristic of the particular basin.

The gravitational normal modes of the basin, computed as part of the investigation, are used to obtain the theoretical forced solutions for the tidal constituents. The latter provide the simulated data for testing of the method and serve as a guide in choosing the most energetic functions for the interpolation. The results of the estimation of the M₂ and K₁ tidal constituents indicate the possibility of recovering the tidal signal with a degree of accuracy well within the error bounds of present satellite techniques.