Oral-presentation at
Workshop Aropa 2001, Castle of Monbach
Local separation of geoid and stationary sea surface topography
using altimetry and gravity data in a selected test area
1Institute of Physical Geodesy;
Darmstadt University of Technology
The determination of the relative geoid with an accuracy of 1 to 2
centimetres
is very important for ocean circulation studies, as the geoid is used as
reference equipotential surface in oceanographic modelling. While the
global geopotential models cannot reach this level, due
to their low spacial resolution, a local geoid could meet this accuracy.
Altimetry data represent a useful tool for estimating the accuracy
of a given local geoid, as the altimetric mean sea surface
coincides with the mean geoid in absence of the stationary sea surface
topography.
The aim of the study is to investigate the accuracy of the "best" local
geoid that can be computed in an quasi-ideal situation:
availability of altimetry and dense marine and land gravity data,
and small stationary and variable sea level topography.
We have selected the Western Mediterranean Sea as test area.
Problems found in the computation
of local highly accurate geoid and local mean sea level solutions
in the selected region are addressed and investigated, e.g. the
the quality of the gravity data available,
the use of altimetry data in the computation of the geoid,
the determination of the geoid in the near-coast area.
Several methods are considered for
the computation of a geoid from gravity and/or altimetry data and
a specified method is suggested. A mean sea level surface is computed
from altimetry and tide gauge data. The accuracy of the geoid is estimated
by comparison with the mean sea level solution.
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