skip navigation link

Directory Title: U.S. East-West Deflections (DEFLEC96)
Principal Investigator: Dr. Dennis G. Milbert

Contributing Organization: NOAA, National Geodetic Survey, N/NGS5
1315 East-West Highway, Room 9349
Silver Spring, MD 20910-3282

Summary: This 2' surface deflection of the vertical grid for the conterminous United States is the DEFLEC96 model. The computation used about 1.8 million terrestrial and marine gravity data held in the National Geodetic Survey gravity data base in July 1996. These data were augmented by gravity data contributions from NIMA (former Defense Mapping Agency). The deflections were obtained by numerical differentiation of cubic spline models along the parallels of the GEOID96 grid. The gravity values are based on the International Gravity Standardization Net 1971 (IGSN71). The deflections are referred to the Geodetic Reference System 1980 (GRS80) ellipsoidal normals. The deflections of the vertical incorporate the reference system relationship between NAD 83(86) and ITRF94(1996.0), the datum offset of NAVD 88, and the contributions from 2951 GPS on leveled benchmarks. The curvature of the plumb line correction has been applied.

Additional information is available at: http://www.ngs.noaa.gov/GEOID/DEFLEC96/

We are particularly grateful to NIMA for their assistance and their data contributions.

Return to the Geoid Data Set Table
Return to Gravity 1999