Use of the topographic deflections of the vertical for computation of the quasigeoid

conference paper

English

The aim of this study is to open the possibility to substitute the gravimetric deflections of the vertical with the topographic ones in some cases. The topographic deflections of the vertical have a great advantage in the data availability for the calculation compared to the gravimetric ones. The detailed gravimetric data for the gravimetric deflections of the vertical calculation are not commonly accessible in many countries. On the contrary, topographic deflections of the vertical can be computed from the global digital elevation model with high resolution, for example SRTM (Shuttle Radar Topography Mission), or GMTED2010 (Global Multi-resolution Terrain Elevation Data 2010). These models are freely available. The profile of Velká Bíteš – Brno – Uherské Hradiště in Czech Republic was chosen as the test area. There are mountainous as well as flat areas on the profile route. There is the greatest gradient of the height anomaly of the Czech Republic in this area. The profile consists of 581 points. On these points, three different types of deflections of the vertical were computed: gravimetric, topographic and deflections from the geopotential model EGM2008. The astrogeodetic deflections of the vertical were measured on 30 evenly distributed points of the profile and the GNSS/levelling was performed on 15 points of the profile. The terrain model GMDET2010 was chosen for the calculation of the topographic deflections of the vertical. The topographic deflections of the vertical were fitted on the deflections calculated from EGM2008. The fitted topographic deflections were compared with the gravimetric deflections, after that, the quasigeoid separation (height anomalies) on the profile was computed using the astronomical levelling method. The root mean square error of the differences between the gravimetric and the fitted topographic deflections of the vertical is 0.53’’ in the meridian component ξ and 0.69’’ in the prime-vertical component η. The root mean square error of the differences in height anomaly calculated from the gravimetric and fitted topographic deflections of the vertical is 23 mm.

Deflections of the vertical, Digital elevation model, Geopotential model, Quasigeoid

KRATOCHVÍL, R.; MACHOTKA, R.; BUDAY, M.

1. 4. 2020

CRC Press/Balkema

London

978-0-367-34651-5

Advances and Trends in Geodesy, Cartography and Geoinformatics II

1st

123

128

6

https://www.taylorfrancis.com/books/e/9780429327025