Reilly, W.I. 1980 The shape of the earth's gravity field in Canterbury, New Zealand, 2: the gravity vector. [s.l.]: [s.n.]. Report / Geophysics Division 165 12 p.
Abstract: The earth's gravity vector can be specified by the intensity of gravity g, and the direction given by astronomic latitude phi and longitude omega. These parameters (g, phi, omega) can be related to the geocentric Cartesian components (gx, gy, gz) of the vector by: gx=g cos phi cos omega, g/ sub y/=g cos phi sin omega, gz=g sin phi. The earth's gravity vector can also be related to the gravity field of a reference ellipsoid in terms of the difference in intensity the free air gravity anomaly Delta g - and the difference in direction, expressed by the easterly eta and northerly xi components of the deflection of the vertical. Parameters of the gravity field in the Canterbury area, New Zealand, have been calculated by the method of least squares collocation from the data of intensity measurements, observations of astronomic latitude and longitude, and estimates of gravity potential anomalies derived from satellite position fixes. The results are given in the form of contour maps of the anomalous terms (Delta g, xi, eta), and of maps of (g, omega, phi) and of (gx, gy, gz), all depicting the relevant parameters on a surface 1 km above sea level. The map of (g, omega, phi) in particular demonstrates that the latitude and longitude coordinate lines are neither smooth nor orthogonal, but fluctuate in response to changes in the intensity of gravity. (auth)
