Astrogeodetic Investigations of the Gravity Field in Central Ohio with a Robotic Total Station

Autor: Erickson, Benjamin Thomas
Jazyk: angličtina
Rok vydání: 2022
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Druh dokumentu: Text
Popis: Earth’s gravity field is a fundamental property in physical geodesy, with the geoid being a quantity of particular interest. As an equipotential surface of gravity that approximates global mean sea level, the geoid represents the figure of the earth and serves a reference for many applications. This thesis presents an experiment to investigate the gravity field in Central Ohio using the techniques of geodetic astronomy. From astronomical observations, certain parameters of the gravity field were estimated, namely the deflection of the vertical and the shape of the geoid.The Total Station Astrogeodetic Control System, recently developed by the United States National Geodetic Survey, is introduced as an instrumentation system. It was used to collect observations at 25 sites in the Columbus region and determine astronomical latitude, longitude, and deflection of the vertical, which provide information about the direction of gravity. Analysis of the data showed that deflections obtained from a 15-minute observation had internal precisions of 0.13 to 0.20 arcseconds. The method of astronomical leveling was used to derive geoid heights from the deflections of the vertical. A model of the geoid surface was developed for the study area, with a median precision of 2.7 centimeters.Three sites were periodically revisited over seven months and observations were consistent within uncertainties. As a check of external accuracy, deflections and geoid heights from this study were compared to published models, showing agreement within 0.3 arcseconds and 5 centimeters, respectively. With the accuracies achievable from the Total Station Astrogeodetic Control System, applications are explored for modeling the shape of the geoid over space and time. The results of the project confirm the value of geodetic astronomy for investigating the gravity field.
Databáze: Networked Digital Library of Theses & Dissertations