The global geopotential and regional gravimetric geoid/quasigeoid models testing using the newly adjusted levelling dataset for New Zealand

Abstract

The jointly adjusted levelling networks at the South and North Islands of New Zealand (in combination with GPS data) are used to assess the accuracy of the currently available regional gravimetric geoid/quasigeoid models (NZGeoid2009, BEM-quasigeoid and KTH-geoid). The least squares analysis is applied to combine the gravity and GPS-levelling data using a three-parametre model. The GPS and levelling data are further used to evaluate the accuracy of the recently released satellite-only global geopotential models (GGMs) compiled using GRACE and GOCE data. The regional accuracy of these GGMs in New Zealand is compared with the combined models EGM2008 and EIGEN-GL04C. The analysis of regional gravimetric solutions reveals that the fit of the KTH geoid model with GPS-levelling data is 12 cm in terms of the standard deviation (STD) of differences. The STD fit of the NZGeoid2009 and BEM quasigeoid models with GPS-levelling data is 14 and 15 cm, respectively. This accuracy is better (except for NZGeoid2009) than the STD fit obtained when applying the average offsets of individual local vertical data. The analysis of GGMs reveals that the GOCE satellite-only model GO-CONS-GCF-2 version TIM-R2 has the best agreement with GPS-levelling data; the STD of differences is 57 cm and the mean of differences is 2 cm.