Can an Earth Gravitational Model Augmented by a Topographic Gravity Field Model Realize the International Height Reference System Accurately?

Abstract

In this study, we evaluate the suitability of recent Earth Gravitational Models (EGMs) for the realization of the International Height Reference System (IHRS) in Canada. Topographic gravity field models have been used to augment EGMs to spatial resolution reaching 2′ (about 4 km), which is comparable to regional geoid models. The advantages of using an EGM over a regional approach for the IHRS are its uniform representation of the Earth’s gravity field and its conformance to international standards and conventions. The main challenge is access to, and best use of knowledge of the regional gravity and topographic data. On the one hand, we determine that two recent hybrid models (EIGEN-6C4 and XGM2019) augmented by topographic signals give geopotential values (Wp) with accuracy of ~0.3 m2 s−2, which is close to those estimated by the Canadian regional geoid models at the 11 International Height Reference Frame sites in Canada. On the other hand, two recent augmented satellite-only models (DIR-R6 and GOCO06s) give Wp with accuracies between 1.5 and 1.7 m2 s−2 in Canada.

Augmented Gravity Field Modelling by Combining EIGEN_6C4 and Topographic Potential Models

“…Ince et al [38] determined augmented model by combining EIGEN-6C4 model with the topographic model. Huang et al [39] evaluated the suitability of augmented GFMs by combining the Earth gravity field model with the topographic model for realizing the height datum unification.…”