Use of potential coefficient models for geoid undulation determinations using a spherical harmonic representation of the height anomaly/geoid undulation difference

This paper suggests that potential coefficient models of the Earth's gravitational potential be used to calculate height anomalies which are then reduced to geoid undulations where such quantities are needed for orthometric height determination and vertical datum definition through a potential coefficient realization of the geoid. The process of the conversion of the height anomaly into a geoid undulation is represented by a height anomaly gradient term and the usual N-ζ term that is dependent on elevation and the Bouguer anomaly. Using a degree 360 expansion of 30' elevations and the OSU91A potential coefficient model, a degree 360 representation of the correction terms was computed. The magnitude of N-ζ reached -3.4 m in the Himalaya Mountains with smaller, but still significant, magnitudes in other mountainous regions.[PUBLICATION ABSTRACT]