Evaluation of quasi-geoid model based on astrogeodetic measurements: case of Latvia

K Morozova,J Balodis,A Zarins,R Jäger,G Silabriedis,I Varna

doi:10.1515/jag-2021-0030

Abstract

AbstractSince the development of GNSS techniques, the determination of a precise quasi-geoid model has become even more actual. In terms of this project the staff of the Institute of Geodesy and Geoinformatics (GGI) has developed a new quasi-geoid model based on DFHRS (Digital Finite-element Height Reference Surface) approach additionally using astrogeodetic measurements – vertical deflections (VD), which can be observed by a Digital zenith camera. This paper evaluates a quasi-geoid model results based on vertical deflections, as a study area using the territory of Latvia: the standard deviation of the solution is equal to 0.006 m with observation residuals after the adjustment of minimum and maximum differences −0.012 and 0.012 accordingly. The standard deviation of quasi-geoid heights and h-H values from LGIA database is equal to 0.012 m with minimum and maximum differences −0.026 and 0.025 accordingly. The post-processed terrestrial VD observations have been compared to VD derivatives from EGM2008 and GGMplus geopotential models. The developed quasi-geoid has been compared to the national quasi-geoid model LV’14 and to the Scandinavian NKG2015.

Highlights

Since the development of GNSS techniques, the determination of a precise quasi-geoid model has become even more actual. In terms of this project the staff of the Institute of Geodesy and Geoinformatics (GGI) has developed a new quasi-geoid model based on DFHRS (Digital Finite-element Height Reference Surface) approach using astrogeodetic measurements – vertical deflections (VD), which can be observed by a Digital zenith camera
This paper evaluates a quasi-geoid model results based on vertical deflections, as a study area using the territory of Latvia: the standard deviation of the solution is equal to 0.006 m with observation residuals after the adjustment of minimum and maximum differences −0.012 and 0.012
Latvian Geospatial Information Agency (LGIA) has developed LV’14 [12], a quasi-geoid model using 4886 relative gravity points measured with a spring gravimeter Scintrex CG-5 [13], these measurements can not be considered to be of a good quality, as the observations were not made in a closed loop

Summary

Introduction

Abstract: Since the development of GNSS techniques, the determination of a precise quasi-geoid model has become even more actual In terms of this project the staff of the Institute of Geodesy and Geoinformatics (GGI) has developed a new quasi-geoid model based on DFHRS (Digital Finite-element Height Reference Surface) approach using astrogeodetic measurements – vertical deflections (VD), which can be observed by a Digital zenith camera. Latvian Geospatial Information Agency (LGIA) has developed LV’14 [12], a quasi-geoid model using 4886 relative gravity points measured with a spring gravimeter Scintrex CG-5 [13], these measurements can not be considered to be of a good quality, as the observations were not made in a closed loop. Our approach is based on Digital Zenith Camera (DZC) observations and can be used as an additional method to relative gravity measurements or as a single technique for quasi-geoid determination.

Deflections of the vertical

The Digital Zenith camera VESTA

Quasi-geoid evaluation and results

Findings

Conclusions