| Summary: | Geodetic coordinates on Australian maps are referenced to the Australian Geodectic Datum 1984 (AGD84). Topographic elevations are referred to the Australian Height Datum (AHD). Conversely, GPS yields 3-D Cartesian coordinates and coordinate differences in the World Geodetic System 1984 (WGS84). The difference between coordinates of the same point on the Earth's surface varies between 150 m to 200 m over continental Australia. This study presents a method of transforming between GPS (WGS84) and AGD84 latitude, longitude and AHD. This permits GPS-aided gravity data to be integrated with other geophysical data referred to the AGD84. A new rigorous formula to simultaneously determine the latitude, free-air and slab Bouguer corrections from GPS and geoid information is derived. It is demonstrated that, if an incorrect elevation datum is used for gravimetric data reduction, a different gravity anomaly is produced.
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