EGM96: The
<A HREF="http://www.gsfc.nasa.gov/"> NASA GSFC </A> and
<A HREF="http://nga.gov.mil"> NIMA </A> Joint Geopotential Model
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A 20x20 QSST was adjusted simultaneously with the geopotential coefficients in
EGM96, and is depicted below. The separation between the altimetric surface,
defined by the
ERS-1
and TOPEX altimeter data, and the geoid is accomplished
through (1) the incorporation of marine gravity data in the surface gravity
normals, and (2) the imposition of a power law constraint on the spectrum
of the QSST, where this power law was derived from a fit to spherical harmonic
coefficients derived from output of the
POCM_4B
ocean circulation model.
We solve for a single QSST for both TOPEX, and
ERS-1 ,
since the two sets
of data are temporally coincident. Furthermore,
the weight for
ERS-1
was selected such that the TOPEX derived QSST would
not change over the TOPEX domain (+/- 66 deg latitude) by more than
2 cm. In addition to the quasi-static terms of the sea surface topography,
a time variable SST to 10x10, consisting of annual and semiannual terms
was also solved for.

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