From Discrete Gravity Survey Data to a High-resolution Gravity Field Representation in the Nordic-Baltic Region

Märdla, Silja; Ågren, Jonas; Strykowski, Gabriel; Oja, Tõnis; Ellmann, Artu; Forsberg, R.; Bilker‐Koivula, Mirjam; Omang, O. C. D.; Paršeliūnas, Eimuntas; Liepiņš, Ivars; Kaminskis, Jānis

doi:10.1080/01490419.2017.1326428

Cited by 19 publications

(10 citation statements)

References 62 publications

(45 reference statements)

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“…Very essential for good results is to use correct or accurate geodetic data. For modelling also gravity data should be verified or cross validated between different survey campaigns and sources [14]. It is great contribution for new NKG2015 geoid model over region, which was released during gravity field meeting International Symposium on Gravity, Geoid and Height Systems 2016 Thessaloniki, Greece on 19 -23 September 2016.…”

Section: Resultsmentioning

confidence: 99%

Common Studies of National Height System in Latvia and Lithuania

Celms¹,

Reke²,

Kaminskis³

2018

Civil Engineering

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Already after our independence in the nineties of the twentieth century, we used common height system-Baltic Normal height system 1977 (BHS 1977). Latter we have made big job for verification and modernization of our geodetic network in the frames of different international campaigns. There we always cooperating with Nordic countries in frames of Nordic Geodetic Commission (NKG). Also we have had sector programme between Denmark and Baltic countries about modernization of geodetic network. Already in that time we carried out common work in the field of gravity survey, levelling and GNSS observation. As European Union member states-Latvia and Lithuania have changed their national height systems to European Vertical Reference System realizations. Latest product of such efforts, we have freely available latest Nordic quasi-geoid model NKG2015, too. For studies of height network consistency in regional and international level we carry out GNSS observation campaigns and making comparison of the obtained survey results and computed ones from different geoid models, for example LV98, NKG2015, EGG2015 etc. In such way, we are making conclusions about quality of geodetic network and giving recommendation for the future work. The aim of the research is using GNSS measurements gain insight for methodology development of geodetic point height testing. To achieve the aim following tasks were set: 1) perform GNSS measurements of first order levelling network points in Latvia and Lithuania; 2) to do data processing to get station coordinates; 3) to compare point elevations. For GNSS measurements use for height determination it is very significantly to use advanced measuring technologies and verified data processing methodology. RMS errors describe high accuracy of performed measurements.

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Section: Resultsmentioning

confidence: 99%

Common Studies of National Height System in Latvia and Lithuania

Celms¹,

Reke²,

Kaminskis³

2018

Civil Engineering

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“…Similar gridding principles were implemented in other studies; see, e.g. Märdla et al (2017) andVarga (2018). The obtained surface gravity anomaly grids were used as input data in all geoid computations (see Sect.…”

Section: Gravity Data Gridding and Spectral Analysismentioning

confidence: 98%

Contribution of GRAV-D airborne gravity to improvement of regional gravimetric geoid modelling in Colorado, USA

Varga¹,

Pitoňák

Novák

et al. 2021

J Geod

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This paper studies the contribution of airborne gravity data to improvement of gravimetric geoid modelling across the mountainous area in Colorado, USA. First, airborne gravity data was processed, filtered, and downward-continued. Then, three gravity anomaly grids were prepared; the first grid only from the terrestrial gravity data, the second grid only from the downward-continued airborne gravity data, and the third grid from combined downward-continued airborne and terrestrial gravity data. Gravimetric geoid models with the three gravity anomaly grids were determined using the least-squares modification of Stokes’ formula with additive corrections (LSMSA) method. The absolute and relative accuracy of the computed gravimetric geoid models was estimated on GNSS/levelling points. Results exhibit the accuracy improved by 1.1 cm or 20% in terms of standard deviation when airborne and terrestrial gravity data was used for geoid computation, compared to the geoid model computed only from terrestrial gravity data. Finally, the spectral analysis of surface gravity anomaly grids and geoid models was performed, which provided insights into specific wavelength bands in which airborne gravity data contributed and improved the power spectrum.

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“…However, nowadays, as a result of the Nordic Geodetic Commission NKG2015 geoid modelling project (Ågren et al 2015, 2016) (which contain extensive data improvements, see e.g. Märdla et al 2017) systematic biases in new geoid models over the region of interest have largely been eliminated. An important result is that the deviations from the new geoid models and national vertical datum can be eliminated by one-dimensional fit, i.e.…”

Section: Determining Sea Surface Heights Interrelations With Geoidmentioning

confidence: 99%

“…The resulting geoid models were evaluated by the Estonian high-precision GNSS-levelling control points, yielding a sub-centimetre accuracy (in terms of StDev). For more details see Märdla et al (2017). The isolines depict the NKG2015 quasigeoid model in the study area.…”

Section: Study Area Data Acquisition and Geoid Modelsmentioning

confidence: 99%

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Assessment of Marine Geoid Models by Ship-Borne GNSS Profiles

Varbla

Ellmann

Märdla

et al. 2017

Geodesy and Cartography

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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.

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From Discrete Gravity Survey Data to a High-resolution Gravity Field Representation in the Nordic-Baltic Region

Cited by 19 publications

References 62 publications

Common Studies of National Height System in Latvia and Lithuania

Common Studies of National Height System in Latvia and Lithuania

Contribution of GRAV-D airborne gravity to improvement of regional gravimetric geoid modelling in Colorado, USA

Assessment of Marine Geoid Models by Ship-Borne GNSS Profiles

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