Validating Geoid Models with Marine GNSS Measurements, Sea Surface Models, and Additional Gravity Observations in the Gulf of Finland

Abstract

Traditionally, geoid models have been validated using GNSS-levelling benchmarks on land only. As such benchmarks cannot be established offshore, marine areas of geoid models must be evaluated in a different way. In this research, we present a marine GNSS/gravity campaign where existing geoid models were validated at sea areas by GNSS measurements in combination with sea surface models. Additionally, a new geoid model, calculated using the newly collected marine gravity data, was validated. The campaign was carried out with the marine geology research catamaran Geomari (operated by the Geological Survey of Finland), which sailed back and forth the eastern part of the Finnish territorial waters of the Gulf of Finland during the early summer of 2018. From the GNSS and sea surface data we were able to obtain geoid heights at sea areas with an accuracy of a few centimetres. When the GNSS derived geoid heights are compared with geoid heights from the geoid models differences between the respective models are seen in the most eastern and southern parts of the campaign area. The new gravity data changed the geoid model heights by up to 15 cm in areas of sparse/non-existing gravity data.

Keywords:

• Dynamic topography
• marine GNSS
• marine gravity
• quasi-geoid
• tide gauge

Acknowledgements

The authors would like to send their warmest thanks to the crew of Geomari (Kimmo, Erkki and Eija), whom made the survey a reality from theory. Additionally, our sincerest thanks to the Swedish colleagues (Per-Anders and Örjan), who made the finalized gravity data from the Geomari available to us. The research was part of the FAMOS (Odin 2016–2018) project, which was co-financed by the European Union within the framework of the Connecting Europe Facility (CEF). We also thank the two anonymous reviewers, the associate editor Dr. Heiner Denker and the editor-in-chief for their valuable comments.

Additional information

Funding

European Union, Connecting Europe Facility (CEF).