Evaluation of the plumb line curvature effect on the deflection of the vertical
The curvature of the plumb line should be considered to find the undistorted geodetic networks without the plumb line curvature effect and to determine the astrogeodetic geoid as well as for other purposes. A few approaches have been developed to estimate the curvature effect. In most of the methods, the need for sufficient gravity data, the knowledge of the density distribution, and other data make the estimation of the plumb line curvature effect a difficult task. Without knowing the density distribution inside the earth, the curvature effect can be determined for the user of Vening Meinesz’s and Molodenskij’s formulae together. However, the procedure is laborious and time-consuming, and the integrations should be extended over the whole earth. This thesis investigates the utilization of the combination of the Stokes’s and Molodenskij’s approaches to determine the curvature effect of the plumb line. In other word, the determination of the curvature effect of the plumb line is based on combining Vening Meinesz’s and Molodenskij’s formulae. In this approach, the integrations will not be extended over the whole earth but a 25x25 minutes rectangular area. A determination of the plumb line curvature effect has been attempted at six stations in New Brunswick. The results show that this approach has been successfully used and can give a higher accuracy. The estimation of the curvature effect of the plumb line is no longer a difficult job.