A superconducting gravimeter on the island of Heligoland for the high-accuracy determination of regional ocean tide loading signals of the North Sea

Research output: Contribution to journal › Article › Research › peer review

Authors

  • Christian Voigt
  • Roman Sulzbach
  • Ludger Timmen
  • Henryk Dobslaw
  • Adelheid Weise
  • Zhiguo Deng
  • Nico Stolarczuk
  • Hartmut Pflug
  • Heino Peters
  • Michael Fietz
  • Maik Thomas
  • Christoph Förste
  • Frank Flechtner

Research Organisations

External Research Organisations

  • Helmholtz Centre Potsdam - German Research Centre for Geosciences (GFZ)
  • Freie Universität Berlin (FU Berlin)
  • Alfred Wegener Institute (AWI) Helmholtz Centre for Polar and Marine Research
  • Technische Universität Berlin
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Details

Original languageEnglish
Pages (from-to)1585-1602
Number of pages18
JournalGeophysical journal international
Volume234
Issue number3
Publication statusPublished - 3 Apr 2023

Abstract

The superconducting gravimeter GWR iGrav 047 has been installed on the small offshore island of Heligoland in the North Sea approximately at sea level with the overall aim of high-accuracy determination of regional tidal and non-tidal ocean loading signals. For validation, a second gravimeter (gPhoneX 152) has been setup within a gravity gradiometer approach to observe temporal gravity variations in parallel on the upper land of Heligoland. This study covers the determination of regional ocean tide loading (OTL) parameters based on the two continuous gravimetric time-series after elimination of the height-dependent gravity component by empirical transfer functions between the local sea level from a nearby tide gauge and local attraction effects. After reduction of all gravity recordings to sea level, both gravimeters provide very similar height-independent OTL parameters for the eight major diurnal and semidiurnal waves with estimated amplitudes between 0.3 nm s −2 (Q 1) and 11 nm s −2 (M 2) and RMSE of 0.1–0.2 nm s −2 for 2 yr of iGrav 047 observations and a factor of 2 worse for 1.5 yr of gPhoneX 152 observations. The mean absolute OTL amplitude differences are 0.3 nm s −2 between iGrav 047 and gPhoneX 152, 0.4 nm s −2 between iGrav 047 and the ocean tide model FES2014b and 0.7 nm s −2 between gPhoneX 152 and FES2014b which is in good agreement with the uncertainty estimations. As by-product of this study, OTL vertical displacements are estimated from the height-independent OTL gravity results from iGrav 047 applying proportionality factors dh/dg for the eight major waves. These height-to-gravity ratios and the corresponding phase shifts are derived from FES2014b. The OTL vertical displacements from iGrav 047 are estimated with amplitudes between 0.4 mm (Q1) and 5.1 mm (M2) and RMSE of 0.1–0.7 mm. These OTL amplitudes agree with FES2014b within 0.0 (M2) and 0.8 mm (K1) with a mean difference of 0.3 mm only. The OTL amplitudes from almost 5 yr of GNSS observations show deviations of up to 6 mm (M 2) compared to vertical displacements from both iGrav 047 and FES2014b, which suggests systematic effects included in the estimation of OTL vertical displacements from GNSS. With the demonstrated accuracy, height-independent sensitivity in terms of gravity and vertical displacements along with the high temporal resolution and the even better performance with length of time-series, iGrav 047 delivers the best observational signal for OTL which is representative for a large part of the North Sea.

Keywords

    Loading of the Earth, Tides and planetary waves, Time variable gravity

ASJC Scopus subject areas

Cite this

A superconducting gravimeter on the island of Heligoland for the high-accuracy determination of regional ocean tide loading signals of the North Sea. / Voigt, Christian; Sulzbach, Roman; Timmen, Ludger et al.
In: Geophysical journal international, Vol. 234, No. 3, 03.04.2023, p. 1585-1602.

Research output: Contribution to journal › Article › Research › peer review

Voigt, C, Sulzbach, R, Timmen, L, Dobslaw, H, Weise, A, Deng, Z, Stolarczuk, N, Pflug, H, Peters, H, Fietz, M, Thomas, M, Förste, C & Flechtner, F 2023, 'A superconducting gravimeter on the island of Heligoland for the high-accuracy determination of regional ocean tide loading signals of the North Sea', Geophysical journal international, vol. 234, no. 3, pp. 1585-1602. https://doi.org/10.1093/gji/ggad147
Voigt, C., Sulzbach, R., Timmen, L., Dobslaw, H., Weise, A., Deng, Z., Stolarczuk, N., Pflug, H., Peters, H., Fietz, M., Thomas, M., Förste, C., & Flechtner, F. (2023). A superconducting gravimeter on the island of Heligoland for the high-accuracy determination of regional ocean tide loading signals of the North Sea. Geophysical journal international, 234(3), 1585-1602. https://doi.org/10.1093/gji/ggad147
Voigt C, Sulzbach R, Timmen L, Dobslaw H, Weise A, Deng Z et al. A superconducting gravimeter on the island of Heligoland for the high-accuracy determination of regional ocean tide loading signals of the North Sea. Geophysical journal international. 2023 Apr 3;234(3):1585-1602. doi: 10.1093/gji/ggad147
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@article{176bf2eec79843f58b6dbcc613891f29,
title = "A superconducting gravimeter on the island of Heligoland for the high-accuracy determination of regional ocean tide loading signals of the North Sea",
abstract = "The superconducting gravimeter GWR iGrav 047 has been installed on the small offshore island of Heligoland in the North Sea approximately at sea level with the overall aim of high-accuracy determination of regional tidal and non-tidal ocean loading signals. For validation, a second gravimeter (gPhoneX 152) has been setup within a gravity gradiometer approach to observe temporal gravity variations in parallel on the upper land of Heligoland. This study covers the determination of regional ocean tide loading (OTL) parameters based on the two continuous gravimetric time-series after elimination of the height-dependent gravity component by empirical transfer functions between the local sea level from a nearby tide gauge and local attraction effects. After reduction of all gravity recordings to sea level, both gravimeters provide very similar height-independent OTL parameters for the eight major diurnal and semidiurnal waves with estimated amplitudes between 0.3 nm s −2 (Q 1) and 11 nm s −2 (M 2) and RMSE of 0.1–0.2 nm s −2 for 2 yr of iGrav 047 observations and a factor of 2 worse for 1.5 yr of gPhoneX 152 observations. The mean absolute OTL amplitude differences are 0.3 nm s −2 between iGrav 047 and gPhoneX 152, 0.4 nm s −2 between iGrav 047 and the ocean tide model FES2014b and 0.7 nm s −2 between gPhoneX 152 and FES2014b which is in good agreement with the uncertainty estimations. As by-product of this study, OTL vertical displacements are estimated from the height-independent OTL gravity results from iGrav 047 applying proportionality factors dh/dg for the eight major waves. These height-to-gravity ratios and the corresponding phase shifts are derived from FES2014b. The OTL vertical displacements from iGrav 047 are estimated with amplitudes between 0.4 mm (Q1) and 5.1 mm (M2) and RMSE of 0.1–0.7 mm. These OTL amplitudes agree with FES2014b within 0.0 (M2) and 0.8 mm (K1) with a mean difference of 0.3 mm only. The OTL amplitudes from almost 5 yr of GNSS observations show deviations of up to 6 mm (M 2) compared to vertical displacements from both iGrav 047 and FES2014b, which suggests systematic effects included in the estimation of OTL vertical displacements from GNSS. With the demonstrated accuracy, height-independent sensitivity in terms of gravity and vertical displacements along with the high temporal resolution and the even better performance with length of time-series, iGrav 047 delivers the best observational signal for OTL which is representative for a large part of the North Sea.",
keywords = "Loading of the Earth, Tides and planetary waves, Time variable gravity",
author = "Christian Voigt and Roman Sulzbach and Ludger Timmen and Henryk Dobslaw and Adelheid Weise and Zhiguo Deng and Nico Stolarczuk and Hartmut Pflug and Heino Peters and Michael Fietz and Maik Thomas and Christoph F{\"o}rste and Frank Flechtner",
note = "This project is funded by the Deutsche Forschungsgemeinschaft (DFG,German Research Foundation)—Project-ID 434617780–SFB 1464 and under Germany's Excellence Strategy—EXC–2123 QuantumFrontiers–390837967 at Leibniz Universit{\"a}t Hannover. Additional support was given by the TIDUS project within the NEROGRAV research unit (DFG Research Unit 2736, Grants: TH864/15–1, DE2174/12–1). The Helgoland Gravimetric Observatory Germany (HELGOG) is part of the Modular Earth Science Infrastructure (MESI) of the GFZ. We thank the Biologische Anstalt Helgoland of AWI for providing a suitable location for this observatory and for technical support. We thank GFZ Section 4.4 {\textquoteleft}Hydrology{\textquoteright} for providing gPhoneX 152. We thank the Institute of Geosciences, Christian-Albrechts-Universit{\"a}t zu Kiel for letting us use the seismological station Helgoland at JKS. The Federal Maritime and Hydrographic Agency (BSH) Hamburg supported us with tide gauge data and analysis details. The Generic Mapping Tools (GMT; Wessel & Smith 1998) were used to prepare Fig. 1. We thank the editor Duncan Agnew, Maxime Mouyen and a second anonymous referee for their very valuable reviews that helped to significantly improve the manuscript.",
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volume = "234",
pages = "1585--1602",
journal = "Geophysical journal international",
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Download

TY - JOUR

T1 - A superconducting gravimeter on the island of Heligoland for the high-accuracy determination of regional ocean tide loading signals of the North Sea

AU - Voigt, Christian

AU - Sulzbach, Roman

AU - Timmen, Ludger

AU - Dobslaw, Henryk

AU - Weise, Adelheid

AU - Deng, Zhiguo

AU - Stolarczuk, Nico

AU - Pflug, Hartmut

AU - Peters, Heino

AU - Fietz, Michael

AU - Thomas, Maik

AU - Förste, Christoph

AU - Flechtner, Frank

N1 - This project is funded by the Deutsche Forschungsgemeinschaft (DFG,German Research Foundation)—Project-ID 434617780–SFB 1464 and under Germany's Excellence Strategy—EXC–2123 QuantumFrontiers–390837967 at Leibniz Universität Hannover. Additional support was given by the TIDUS project within the NEROGRAV research unit (DFG Research Unit 2736, Grants: TH864/15–1, DE2174/12–1). The Helgoland Gravimetric Observatory Germany (HELGOG) is part of the Modular Earth Science Infrastructure (MESI) of the GFZ. We thank the Biologische Anstalt Helgoland of AWI for providing a suitable location for this observatory and for technical support. We thank GFZ Section 4.4 ‘Hydrology’ for providing gPhoneX 152. We thank the Institute of Geosciences, Christian-Albrechts-Universität zu Kiel for letting us use the seismological station Helgoland at JKS. The Federal Maritime and Hydrographic Agency (BSH) Hamburg supported us with tide gauge data and analysis details. The Generic Mapping Tools (GMT; Wessel & Smith 1998) were used to prepare Fig. 1. We thank the editor Duncan Agnew, Maxime Mouyen and a second anonymous referee for their very valuable reviews that helped to significantly improve the manuscript.

PY - 2023/4/3

Y1 - 2023/4/3

N2 - The superconducting gravimeter GWR iGrav 047 has been installed on the small offshore island of Heligoland in the North Sea approximately at sea level with the overall aim of high-accuracy determination of regional tidal and non-tidal ocean loading signals. For validation, a second gravimeter (gPhoneX 152) has been setup within a gravity gradiometer approach to observe temporal gravity variations in parallel on the upper land of Heligoland. This study covers the determination of regional ocean tide loading (OTL) parameters based on the two continuous gravimetric time-series after elimination of the height-dependent gravity component by empirical transfer functions between the local sea level from a nearby tide gauge and local attraction effects. After reduction of all gravity recordings to sea level, both gravimeters provide very similar height-independent OTL parameters for the eight major diurnal and semidiurnal waves with estimated amplitudes between 0.3 nm s −2 (Q 1) and 11 nm s −2 (M 2) and RMSE of 0.1–0.2 nm s −2 for 2 yr of iGrav 047 observations and a factor of 2 worse for 1.5 yr of gPhoneX 152 observations. The mean absolute OTL amplitude differences are 0.3 nm s −2 between iGrav 047 and gPhoneX 152, 0.4 nm s −2 between iGrav 047 and the ocean tide model FES2014b and 0.7 nm s −2 between gPhoneX 152 and FES2014b which is in good agreement with the uncertainty estimations. As by-product of this study, OTL vertical displacements are estimated from the height-independent OTL gravity results from iGrav 047 applying proportionality factors dh/dg for the eight major waves. These height-to-gravity ratios and the corresponding phase shifts are derived from FES2014b. The OTL vertical displacements from iGrav 047 are estimated with amplitudes between 0.4 mm (Q1) and 5.1 mm (M2) and RMSE of 0.1–0.7 mm. These OTL amplitudes agree with FES2014b within 0.0 (M2) and 0.8 mm (K1) with a mean difference of 0.3 mm only. The OTL amplitudes from almost 5 yr of GNSS observations show deviations of up to 6 mm (M 2) compared to vertical displacements from both iGrav 047 and FES2014b, which suggests systematic effects included in the estimation of OTL vertical displacements from GNSS. With the demonstrated accuracy, height-independent sensitivity in terms of gravity and vertical displacements along with the high temporal resolution and the even better performance with length of time-series, iGrav 047 delivers the best observational signal for OTL which is representative for a large part of the North Sea.

AB - The superconducting gravimeter GWR iGrav 047 has been installed on the small offshore island of Heligoland in the North Sea approximately at sea level with the overall aim of high-accuracy determination of regional tidal and non-tidal ocean loading signals. For validation, a second gravimeter (gPhoneX 152) has been setup within a gravity gradiometer approach to observe temporal gravity variations in parallel on the upper land of Heligoland. This study covers the determination of regional ocean tide loading (OTL) parameters based on the two continuous gravimetric time-series after elimination of the height-dependent gravity component by empirical transfer functions between the local sea level from a nearby tide gauge and local attraction effects. After reduction of all gravity recordings to sea level, both gravimeters provide very similar height-independent OTL parameters for the eight major diurnal and semidiurnal waves with estimated amplitudes between 0.3 nm s −2 (Q 1) and 11 nm s −2 (M 2) and RMSE of 0.1–0.2 nm s −2 for 2 yr of iGrav 047 observations and a factor of 2 worse for 1.5 yr of gPhoneX 152 observations. The mean absolute OTL amplitude differences are 0.3 nm s −2 between iGrav 047 and gPhoneX 152, 0.4 nm s −2 between iGrav 047 and the ocean tide model FES2014b and 0.7 nm s −2 between gPhoneX 152 and FES2014b which is in good agreement with the uncertainty estimations. As by-product of this study, OTL vertical displacements are estimated from the height-independent OTL gravity results from iGrav 047 applying proportionality factors dh/dg for the eight major waves. These height-to-gravity ratios and the corresponding phase shifts are derived from FES2014b. The OTL vertical displacements from iGrav 047 are estimated with amplitudes between 0.4 mm (Q1) and 5.1 mm (M2) and RMSE of 0.1–0.7 mm. These OTL amplitudes agree with FES2014b within 0.0 (M2) and 0.8 mm (K1) with a mean difference of 0.3 mm only. The OTL amplitudes from almost 5 yr of GNSS observations show deviations of up to 6 mm (M 2) compared to vertical displacements from both iGrav 047 and FES2014b, which suggests systematic effects included in the estimation of OTL vertical displacements from GNSS. With the demonstrated accuracy, height-independent sensitivity in terms of gravity and vertical displacements along with the high temporal resolution and the even better performance with length of time-series, iGrav 047 delivers the best observational signal for OTL which is representative for a large part of the North Sea.

KW - Loading of the Earth

KW - Tides and planetary waves

KW - Time variable gravity

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