Geiod evaluation in Australia—a status report

The history of both local and geocentric geoid evaluation for Australia is reviewed and the present status of detailed geoid computation given. As of December, 1990 all of Australia has been evaluated at a resolution of 0.1° by the Geodetic Services Section of AUSLIG, using OSU89A as the reference model, and detailed gravity from a modified version of the Australian Gravity Data Base. Tests which compare the model-generated gravity field against the observed gravity field show that OSU89A gives the best fit to the gravity field (and hence, presumably, to the geoid) of all available models to date. Tests have also shown that large (up to 3m) differences in the geoid height exist between OSU89A and OSU86E, suggesting that detailed geoid determinations based upon the earlier versions of the OSU models are sub-optimal.