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Regional Models

Australia (AUSGEOID2020)

  Authors: N.J. Brown, et al.     Created: 2020    Resp: AUSLIG  
      Status: PUBLIC    
AUSGeoid2020 is a combined gravimetric-geometric model. The gravimetric component, called AGQG 2017, is a 1' by 1' grid of ellipsoid-quasigeoid separation values created using data from gravity satellite missions (e.g., GRACE, GOCE), re-tracked satellite altimetry, localised airborne gravity, land gravity data from the Australian national gravity database and a Digital Elevation Model to apply terrain corrections. The geometric component is a 1' by 1' grid of separation values from the quasigeoid to the Australian Height Datum (AHD) and is developed using a dataset of collocated GNSS ellipsoidal height and AHD heights. The geometric component attempts to account for an offset between AHD and the quasigeoid that ranges from about -0.5 m (AHD below quasigeoid) in the southwest of Australia to about +0.5 m (AHD above quasigeoid) in the northeast of Australia. The offset between AHD and the quasigeoid is primarily due to the method by which AHD was realised. Given that the warmer, less dense water off the coast of northern Australia is approximately one metre higher than the cooler, denser water off the coast of southern Australia, by constraining each of the tide gauges to zero AHD, the effects of sea surface topography were propagated into the adjustment. The main difference with respect to the previous model AUSGeoid09 is that location-specific uncertainties are now provided. A comparison of AUSGeoid2020 with independent GNSS-levelling data shows differences with a standard deviation of 27 mm.

W.E. Featherstone, J.C. McCubbine, N.J. Brown, S.J. Claessens, M.S. Filmer. J.F. Kirby (2018). The first Australian gravimetric quasigeoid model with location-specific uncertainty estimates. Journal of Geodesy, 92(2), pp. 149–168. DOI: 10.1007/s00190-017-1053-7-1053-7
N.J. Brown, J.C. McCubbine, W.E. Featherstone, N. Gowans, A. Woods, I. Baran (2018). AUSGeoid2020 combined gravimetric–geometric model: location-specific uncertainties and baseline-length-dependent error decorrelation. Journal of Geodesy, 92(12), pp. 1457–1465. DOI: 10.1007/s00190-018-1202-7