Assessment of Marine Geoid Models by Ship-Borne GNSS Profiles

Abstract

Even though the entire Baltic Sea is included in previous geoid modelling projects such as the NKG2015 and EGG07, the accuracy of contemporary geoid models over marine areas remains unknown, presumably being offshore around 15–20 cm. An important part of the international cooperation project FAMOS (Finalising Surveys for the Baltic Motorways of the Sea) efforts is conducting new marine gravity observations for improving gravimetric quasigeoid modelling. New data is essential to the project as the existing gravimetric data over some regions of the Baltic Sea may be inaccurate and insufficiently scarce for the purpose of 5 cm accuracy geoid modelling. Therefore, it is important to evaluate geoid modelling outcome by independent data, for instance by shipborne GNSS measurements. Accordingly, this study presents results of the ship-borne marine gravity and GNSS campaign held on board the Estonian Maritime Administration survey vessel “Jakob Prei” in West-Estonian archipelago in June/July 2016. Emphasis of the study is on principles of using the GNSS profiles for validation of existing geoid models, post-processing of GNSS raw data and low-pass filtering of the GNSS results. Improvements in geoid modelling using new gravimetric data are also discussed. For example, accuracy of geoid models including the new marine gravity data increased 11 mm as assessed from GNSS profiles. It is concluded that the marine GNSS profiles have a potential in providing complementary constraints in problematic geoid modelling areas.

Analysis of the Dynamic Height Distribution at the Estuary of the Odra River Based on Gravimetric Measurements Acquired with the Use of a Light Survey Boat—A Case Study

“…Dynamic gravimetric measurements are closely related to accurate inertial measurements. Sea measurements are known to have high accuracy and resolution for the acquired data [ 17 ] compared with other types of dynamic gravimetric measurements (satellite-, aviation- [ 18 ] or altimetry-based methods). The quality of the data obtained is inherently dependent on the stability of the measurement platform, because such measurements involve recording kinematic parameters of the platform transporting the gravity meter.…”

Gravity Measurements along Commercial Ferry Lines in the Baltic Sea and Their Use for Geodetic Purposes

“…The tracks shown in Figure 1 cover part of the FAMOS project area. The FAMOS project aimed to cover the entire Baltic Sea with similar campaigns performed by different project partners and is complementary to other studies such as geoid evaluation (see Ågren et al 2016a, 2016b, 2019, Bilker-Koivula et al 2017, Johann et al 2020, Lu et al 2019, Varbla et al 2017.…”

“…Since 2014, about 20 "dedicated" and non-dedicated (piggy-back) shipborne gravimetry campaigns have been performed in the Baltic Sea by different institutions and agencies which aimed various scientific outcomes (Bilker-Koivula et al 2017, Nordman et al 2018, Varbla et al 2017.…”

Validation of Copernicus Sea Level Altimetry Products in the Baltic Sea and Estonian Lakes

“…Antenna reference points were connected to the sea level (H in Figure 3) using a total station (Figure 5a). Two antennas were used to eliminate the risks when one receiver stops working and to filter out vessel fluctuations [25,26]. Measurements were carried out on the same day of the satellite overpass; the weather was calm during all measurements (Table 2).…”