|PR/VI Terrain Corrected Free Air Anomalies (96)
|This 2’ gravity anomaly grid for the Puerto Rico and the Virgin Islands is NOT the
input data set used in development of the GEOID96 model. This gravity grid models
the 26,000 terrestrial and marine gravity data held in the National Geodetic Survey
gravity data base in July 1996. The data used in this grid have NOT been augmented
by gravity data contributions from NGA (former National Imagery and Mapping Agency
(former Defence Mapping Agency)). Please note that the GEOID96 model itself does contain
the NGA (former National Imagery and Mapping Agency) contributions. These gravity
values are based on the International Gravity Standardization Net 1971 (IGSN71). Terrain
corrected, atmospherically corrected, Bouguer anomalies were computed with respect
to the Geodetic Reference System 1980 (GRS80) using NAD83 and NAVD88 coordinates.
Terrain corrections were computed by an FFT method from 6" digital elevation data.
These complete Bouguer anomalies were gridded by splines in tension. The free air
anomaly grid was obtained by restoring the Bouguer plate with a 2’ mean elevation
grid. Additional information is available at: http://www.ngs.noaa.gov/GEOID/geoid.html