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Regional Models

New Zealand (NZGEOID09)

  Authors: S. Classens, et al.     Created: 2009    Resp: M.J. Amos  
      Status: PUBLIC    
The New Zealand Quasigeoid 2009 (NZGeoid09) was the official geoid for New Zealand until it was replaced by the NZGeoid2016 in June 2016. The NZGeoid09 model is distributed by Land Information New Zeland (LINZ), it is produced on a one arc-minute grid (approximately 1.8 kilometres) over the New Zealand continental shelf (160° E to 170° W, 25° S to 60° S) and it is referred to the GRS80 ellipsoid. It was calculated by enhancing the EGM2008 global model using a combination of land, sea and satellite based gravity observations, while GPS-levelling observations were not used. With respect to the predecessor NZGeoid05, the input data for the NZGeoid09 model include also DNSC08 gravity anomalies on sea. As for the gravimetric quasi-geoid determination, firstly the global gravity model up to degree and order 2160 was removed from the gridded gravity anomalies in the computation area and then the residual anomalies were subjected to a 1D FFT Stokes integration with kernel modifications. The quasi-geoid is finally obtained by adding back the global model contribution. The method is iterated to account for the offsets among the 13 different local vertical datums in New Zealand, thus providing corrections to the input gravity anomalies. The NZGeoid09 model has an expected accuracy of 6 cm based on comparisons with GPS-levelling observations throughout New Zealand.

S.J. Claessens, C. Hirt, M.J. Amos, W.E. Featherstone, J.F. Kirby (2011). The NZGEOID09 model of New Zealand. Survey Review, 43, pp. 2-15.
S. Classens, C. Hirt, W.E. Featherstone, J.F. Kirby (2009). Computation of a new gravimetric quasigeoid model for New Zealand. Technical report prepared for Land Information New Zealand by Western Australia Centre for Geodesy.

New Zealand