PR/VI East-West Deflections (DEFLEC96)

This 2' surface deflection of the vertical grid for Puerto Rico and the Virgin Islands is distributed as the DEFLEC96 model. The computation used about 26,000 terrestrial and marine gravity data held in the National Geodetic Survey gravity data base in July 1996. These data were augmented bygravity data contributions from NGA (former National Imagery and Mapping Agency) (formerDefense Mapping Agency).The deflections wereobtained by numerical differentiation of cubicspline models along the parallels of the GEOID96grid. The gravity values are based on theInternational Gravity Standardization Net 1971IGSN71). The deflections are referred to in theGeodetic Reference System 1980 (GRS80)ellipsoidal normals. The curvature of the plumbline correction has been applied. We areparticularly grateful to NGA (former National Imagery and Mapping Agency) for theirassistance and their data contributions.