The New Gravity System: Changes in International Gravity Base Values and Anomaly Values
Abstract
The effect of adopting the Geodetic Reference System 1967 (GRS 67) theoretical gravity formula and the International Gravity Standardization Net 1971 (IGSN 71) on gravity anomaly values is assessed. The gravity standard represented in the IGSN 71 values is shown to not conform to that of modern absolute gravity values as well as one might expect although, overall, the apparent discrepancy does not appear to be greater than about 0.03 mgal/1000 mgal change. That the source of error probably lies in the IGSN 71 adjustment is brought out by the close agreement (0.03 mgal) for pendulum and absolute gravity intervals between Washington and Teddington and Paris and Teddington which differ by approximately 0.1 mgal from the IGSN 71 intervals between these sites. The Potsdam datum correction of -14.0 mgal incorporated in the IGSN 71 values is shown to be essentially correct to within 0.03 mgal. Evaluation of 773 international gravity values published by Woollard and Rose (1963), which have been used extensively for gravity control, using the IGSN 71 values as a standard shows: (A) there is no detectable difference in gravity standard defined for observations at pendulum sites except in South America and India; (B) the median average datum difference relative to the IGSN 71 values is +14.7 mgal; (C) On an areal basis the gravity standard difference defined in South America, which amounts to 0.2 mgal/1000 mgal, characterizes the Woollard/Rose values in other areas but is masked by compensating tares (datum shifts) when only the data for pendulum sites is considered.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 1980
- Accession Number
- ADA095615
Entities
People
- George P. Woollard
- Valerie M. Godley
Organizations
- University of Hawaiʻi System