The gravity station data (59,933 records) were compiled by various organizations. This data base was received in June, 1993. Principal gravity parameters include Free-air Anomalies and Simple Bouguer Anomalies (no terrain correction applied). The following assumptions have been made: the observed gravity values are referenced to the International Gravity Standardization Net 1971 (IGSN 71); the gravity anomaly computation uses the Geodetic Reference System 1967 (GRS 67) theoretical gravity formula.

The gravity station data (152,624 records) were compiled by the University of Texas at Dallas. This data base was received in June 1992. Principal gravity parameters include Free-air Anomalies and Simple Bouguer Anomalies (no terrain correction applied). The observed gravity values are referenced to the International Gravity Standardization Net 1971 (IGSN 71). The gravity anomaly computation uses the Geodetic Reference System 1967 (GRS 67) theoretical gravity formula. The data are randomly distributed within the boundaries and offshore of South America.

The gravity station data (9,050 records), were observed and processed by the Instituto Geografico Agustin Codazzi(IGAC), in Colombia from 1958 to 1996. This data base was received in April, 1997. Principal gravity parameters include Free-air anomalies and both Simple and Complete Bouguer anomalies. The gravity anomaly values were computed using the GRS80 ellipsoid.

The National Geophysical Data Center (NGDC) of NOAA, in cooperation with the National Geodetic Survey of NOAA, have published a Gravity CD-ROM containing observed and derived gravity measurements. Contributions to this data compilation include many national and international organizations, in both academia and government. The compact disc contains almost 620 Mbytes of data, partitioned into 1486 files. Approximately 25 percent of the data are observed values -- regional station data collections (separated primarily by contributors) and absolute gravity measurements. Grids and other derived summary data sets represent another 65 percent of the data. The remaining 10 percent of the disc contains geopolitical base map reference data and software.

A 1 kilometer Bouguer anomaly grid for the country of Bolivia.Number of columns is 550 and number of rows is 900. The order of the data is from the lower left to the right and then up one row.

The gravity station data (1,522 records) were compiled by the Portland State University. This data base was received in August 1990. Principal gravity parameters include Free-air Anomalies and Complete Bouguer Anomalies (terrain correction applied). The observed gravity values are referenced to the International Gravity Standardization Net 1971 (IGSN 71). The gravity anomaly computation uses the Geodetic Reference System 1967 (GRS 67) theoretical gravity formula. The data are randomly distributed within the boundaries of the greater Portland area.

The gravity station data (55,907 records) were gathered by various governmental organizations (and academia) using a variety of methods. This data base was received in March 1993. Principal gravity parameters include Free-air Anomalies and Simple Bouguer Anomalies (no terrain correction applied). The observed gravity values are referenced to the International Gravity Standardization Net 1971 (IGSN 71) and the gravity anomaly computation uses the Geodetic Reference System 1967 (GRS 67) theoretical gravity formula. The spatial resolution of the data is randomly distributed within the boundaries of Minnesota.