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Description:
GEOID93 is a geoid model for the United States computed by the National Geodetic Survey (NGS).
It is referred to the GRS80 normal ellipsoid. It has a 3'x3' spatial resolution in latitude and
longitude. It is based on over 1.8 million terrestrial and ship gravity values, including data for Hawaii and Puerto Rico,
but not for Alaska. The geoid determination is based a convolution of gravity data and a spherical Stokes kernel, by
exploiting a Fast Fourier Transform (FFT) technique. This computation is performed in the framework of a remove-restore
procedure, where long wavelengths come from the OSU91A geopotential model. By comparing the GEOID93 model with GPS/levelling
data, the resulting accuracy is about 10 cm (one sigma) over length scales of 100 km. Better accuracy is seen over shorter lengths.
Because of better data quality and coverage, and better computational procedures, GEOID93 possesses better accuracy in mountains
when compared to GEOID90.
References:
D.G. Milbert (1993). GEOID93: A high-resolution geoid for the United States, G&GS Update, Coast and Geodetic Survey, Vol. 5(3), Silver Spring, MD.
D.G. Milbert, D. Schultz (1993). GEOID, The National Geodetic Survey geoid computation program. Geodetic Services Division, National Geodetic Survey, NOAA,
Silver Spring, MD.
Web of Science ID:
DRCI:DATA2017015010667898
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