North American height datums and their offsets: Evaluation of the GOCE-based global geopotential models in Canada and the USA

Abstract

The Gravity field and steady-state Ocean Circulation Explorer (GOCE) dedicated satellite gravity field mission was launched on March 17, 2009. Three generations of global geopotential models have been computed and released based on the data collected by GOCE since then. The first generation of the models has been computed from the first two months of the data, and more observations, ranging from six to eight months, have been used in the computation of the second generation models. The third generation models are based on eighteen months of GOCE observations. The evaluation of these models is important in view of Canada’s and the USA’s decision to modernize and unify their vertical datums based on the geoid. In this paper, the released GOCE-based models are evaluated using 1315 and 18399 GNSS/levelling stations in Canada and the USA, respectively. In addition, three GRACE-based models and EGM2008 are included in the evaluation procedure as ’pre-GOCE era’ models to identify any improvements brought by the new GOCE-based models in the region. The results provide evidence that the third generation time-wise (go_cons_gcf_2_tim_r3) and direct approach (go_cons_gcf_2_dir_r3) GOCE models perform slightly better than the rest of the geopotential models in Canada and the USA