Determination of partial geoidal parameters over the Indian sub-continent

Abstract

The paper presents values of partial geoidal parametersN, ξ and η which define the departure of the geoid from the reference spheroid, at 1° intervals over the Indian subcontinent. These values represent contributions arising from the gravity anomaly data over the entire earth's surface, except for that from a 6°×6° element around the immediate neighbourhood of the point. Complete values of these parameters at a point can be obtained simply by adding to these partial values, contributions from the 6°×6° element circumscribing that point. The objective of the study was to provide a ready basis for updating the geoidal parameters at the initial reference point as and when the density and quality of local gravity data around it improve. These computations once made, would also facilitate calculation of geoidal parameters at a fairly large number of astro-geodetic stations apart from that at the initial reference point, which should lead to considerably more precise value of the absolute datum of the Indian geodetic dasystem.