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The estimation of tidal constituents, quasi-stationary sea surface
topography and associated flow fields from satellite altimetry by means
of characteristic functions.

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Braulio V. Sanchez
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NASA/GSFC Geodynamics Branch
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Abstract:
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Tidal models for the main diurnal and semidiurnal constituents have
been computed from TOPEX altimeter data and a set of Proudman functions
computed numerically in the space defined by the ocean basins. The
surface height field due to any tidal constituent can be expanded in
terms of the eigenfunctions of the velocity potential (Proudman
functions) with coefficients estimated in a least squares sense from a
field of discrete data points obtained from altimetry, tide gauges,
bottom pressure sensors, etc. The data field used in this study
consisted of approximately 15 months of TOPEX altimetry in the form of
collinear differences.

The quasi-stationary sea surface topography (QSST) and associated
oceanic circulation was determined by means of a characteristic
function technique. The data field was provided by the first year of
altimeter data from the TOPEX/POSEIDON mission. The method requires the
numerical determination of the eigenfunctions spanning the
streamfunction field and the associated characteristic functions from
the balance equation. The former yields the flow field and the latter
the surface height distribution, or QSST.