A New Model of Quasigeoid for the Baltic Sea Area

Adam Lyszkowicz,Monika Birylo,Janusz B Zielinski,Jolanta Nastula

doi:10.3390/rs13132580

Adam Lyszkowicz, Monika Birylo + Show 2 more

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https://doi.org/10.3390/rs13132580

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Abstract

The Space Research Centre in Warsaw is participating in the ESA project “Geodetic SAR for Height System Unification and Sea Level Research”. To observe the absolute sea level and enable the unification of the height systems, the physical heights of the tide gauge stations referring to a common equipotential surface (quasigeoid/geoid) are needed. This paper describes the new quasigeoid model for the area of the Baltic sea. The quasigeoid calculation was carried out according to the Helmert method, in which the topography is condensed on a layer lying on the geoid. Airborne gravity anomalies from the Baltic area and terrestrial anomalies from Sweden, Finland, Denmark, Lithuania, Latvia, and Poland were used. The necessary terrain corrections have been computed from a digital terrain model based on the SRTM30 model. To compute the long-wavelength part of the quasigeoid, the geopotential models GOCE-DIR6, GOCO06s, and EIGEN-6C4 were used; therefore, the three solutions have been obtained. All calculations were done in a zero-tide system. The new quasigeoid model is obtained on a regular 1.5’ × 3.0’ grid in the GRS80 reference system, covering the Baltic Sea and the surrounding area 52° < ϕ < 68° and 11° < λ < 30°. These gravimetric quasigeoids were compared to quasigeoid undulations derived at 29 GNSS/leveling points of the ASG-EUPOS permanent network, located in the study area. Our calculations show that the accuracy of the calculated quasigeoids is almost the same in all three cases and is about ±0.04 meters. Finally, quasigeoid anomalies were interpolated at the Polish tide gauge stations. The new gravimetric quasigeoid solution could be very important for height system unification, for geophysical purposes as well as for engineering purposes.

Highlights

The Space Research Centre in Warsaw is participating in the ESA project “GeodeticSAR for Height System Unification and Sea Level Research”
Comparisons have shown that quasigeoid anomalies at the tide gauge stations calculated from different geopotential models differ from 1 to 2 cm (Figure 11)
Comparisons have shown that quasigeoid anomalies at the tide gauge stations calcuThe computation of a regional gravimetric geoid model with proper accuracy is a diflated from different geopotential models differ from 1 to 2 cm (Figure 11)

Summary

Introduction

SAR for Height System Unification and Sea Level Research”. To observe the absolute sea level and enable the unification of the height systems, the physical heights of the tide gauge stations, referring to a common equipotential surface, e.g., the geoid, are needed [1]. The geoid is of fundamental importance for geodesy, oceanography, and physics of the solid Earth and was introduced by C.F. Gauss as a refined model of the figure of the. The geoid/quasigeoid is a reference surface for vertical datum [3], orthometric heights [4], a transformation of ellipsoidal heights into orthometric heights [5], local and regional vertical datum unification [6], and satellite orbits prediction [7].

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