Impact of the UNB topographical density model on precise geoid determination in the high mountainous region

Abstract

A precise gravimetric geoid model is computed utilising Stokes’s formula, supposing an absence of topography above the geoid. Subsequently, the geoid model undergoes a simple correction for topographic masses, the constant density is taken as 2670 kg/m³. Notably, the true density of topographical mass deviates by approximately ±20% from this constant value. Recently, the University of New Brunswick in Canada released a global topographical density model at a 30 arc-second resolution. This paper investigates the impact of incorporating this model on the precision of the gravimetric geoid within a mountainous region in the Colorado test region. Numerical findings reveal that variations in geoid undulation attributable to this model can extend to a few decimetres, a discrepancy that cannot be neglected in geoid modelling with one-centimetre precision. It is therefore recommended that the considerable impact of topographic density fluctuations on geoid determination be taken into account, particularly in mountainous regions.

Keywords:

• Global crust model
• Gravimetric geoid determination
• LSMS method
• UNB
• Terrestrial gravity data

Acknowledgements

The software used in the study was developed by Abbak and Ustun (2015). The author thanks to Prof. Abbak for providing the software.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Notes on contributors

Nazan Yilmaz

Nazan Yilmaz is a lecturer in the Division of Geodesy in the Department of Geomatics Engineering at Karadeniz Technical University in Türkiye. She obtained her PhD degree with a thesis titled ‘Comparison of the Geoids Determined with Different Methods and Data for Turkey’ in 2011, and her MSc degree with a thesis titled ‘Evaluation of Different Geodetic Heights’ in 2005. She worked as a research assistant from 2002 to 2011 as an Assistant Professor from 2011 to 2022 and she has been working as an associate professor since 2022 in the Department of Geomatics Engineering at Karadeniz Technical University.