Description:
USGG2003 is a gravimetric geoid model for conterminous United States computed by the National Geodetic Survey (NGS).
It is referred to the GRS80 normal ellipsoid in the ITRF00 frame. It has a 1'x1' spatial resolution in latitude and longitude.
The main difference in the input data between USGG2003 and the predecessor G99SSS is the replacement of KMS98 offshore free-air
gravity anomalies with the GSFC00.1 model. The geoid determination is based on the use of the one-dimensional spherical Fast
Fourier Transform (FFT) to evaluate Stokes' integral. This computation is performed in the framework of a remove-restore procedure,
where long wavelengths come from the EGM96 geopotential model. The terrain correction is based on 30-arc-second and 3-arc-second
digital elevation models. By comparing the USGG2003 model with GPS/levelling data (ITRF00/NAVD88), a systematic offset at the level
of 50 cm is present. The GEOID03 hybrid model is computed by fitting 14185 points (NAD83/NAVD88) with the USGG2003 gravimetric model,
also taking into account the relationships between NAD83 and ITRF00 reference frames. The fitting is performed by multi-matrix least
squares collocation after removing a trend to the residuals. Therefore the GEOID03 model directly relates NAD83(86) ellipsoid heights
and NAVD88 orthometric heights. The differences between GEOID03 and GPS/levelling (NAD83/NAVD88) benchmarks have an rms of 2.4 cm.
GEOID03 and GEOID99 are statistically very similar, with the largest differences between 10 and 15 cm in coastal and mountainous regions.
References:
D.R. Roman, Y.M. Wang, W. Henning, J. Hamilton (2004). Assessment of the New National Geoid Height Model, GEOID03. Surveying and Land Information Science, 64(3),
pp. 153-162.
Web of Science ID:
DRCI:DATA2019017015400561
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