Reilly, W.I. 1981 The shape of the earth's gravity field in Canterbury, New Zealand, 3: gravity potential. [s.l.]: [s.n.]. Report / Geophysics Division 173 11 p.
Abstract: The anomalous gravity potential can be derived at a point by a comparison of the height of the point above a reference ellipsoid, determined by satellite doppler methods, with the orthometric height found by levelling. Such data are combined with observations of deflection of the vertical and of free-air gravity anomalies using the method of least square collocation to allow interpolation of the anomalous potential at any point, together with an estimate of the error covariance of the interpolated value. Using these observations, the anomalous gravity potential has been interpolated on a grid of points, 5 km apart, at 1 km above sea level in the Canterbury area, New Zealand. The results are shown as a map of the height anomaly of the equipotential surface, or the vertical separation between a gravity equipotential surface of the real earth and the surface of the same potential value pertaining to the reference ellipsoid. The height anomaly in the Canterbury area ranges from +3 m to +7 m; the mean value depends on the datum shift adopted to relate the New Zealand Reference Ellipsoid to the NWL9D datum of satellite positions. The satellite stations provide reference points for the height anomaly, and the detail between these is provided by observations of deflection of the vertical and of the gravity anomaly
