Postglacial gravity change in Fennoscandia

Three decades of repeated absolute gravity observations

authored by: Per Anders Olsson, Kristian Breili, Vegard Ophaug, Holger Steffen, Emil Nielsen, Tõnis Oja, Ludger Timmen, M. Bilker
Abstract: For the first time, we present a complete, processed compilation of all repeated absolute gravity (AG) observations in the Fennoscandian postglacial land uplift area and assess their ability to accurately describe the secular gravity change, induced by glacial isostatic adjustment (GIA). The data set spans over more than three decades and consists of 688 separate observations at 59 stations. Ten different organizations have contributed with measurements using 14 different instruments. The work was coordinated by the Nordic Geodetic Commission (NKG). Representatives from each country collected and processed data from their country, respectively, and all data were then merged to one data set. Instrumental biases are considered and presented in terms of results from international comparisons of absolute gravimeters. From this data set, gravity rates of change (ġ) are estimated for all stations with more than two observations and a timespan larger than 2 yr. The observed rates are compared to predicted rates from a global GIA model as well as the state of the art semi-empirical land uplift model for Fennoscandia, NKG2016LU. Linear relations between observed ġ and the land uplift, ḣ (NKG2016LU) are estimated from the AG observations by means of weighted least squares adjustment as well as weighted orthogonal distance regression. The empirical relations are not significantly different from the modelled, geophysical relation ġ=0.03-0.163(±0.016) ḣ. We also present a ġ-model for the whole Fennoscandian land uplift region. At many stations, the observational estimates of ġ still suffer from few observations and/or unmodelled environmental effects (e.g. local hydrology). We therefore argue that, at present, the best predictions of GIA-induced gravity rate of change in Fennoscandia are achieved by means of the NKG2016LU land uplift model, together with the geophysical relation between ġ and ḣ.
Organisation(s): Institute of Geodesy
External Organisation(s): Statens Kartverk (Norwegian Mapping Authority)
Norwegian University of Life Sciences
Technical University of Denmark
Estonian Land Board
Finnish Geodetic Institute (FGI)
Lantmäteriet - The Swedish Mapping, Cadastral, and Land Registration Authority
Type: Article
Journal: Geophysical journal international
Volume: 217
Pages: 1141-1156
No. of pages: 16
ISSN: 0956-540X
Publication date: 30.01.2019
Publication status: Published
Peer reviewed: Yes
ASJC Scopus subject areas: Geophysics, Geochemistry and Petrology
Electronic version(s): https://doi.org/10.1093/gji/ggz054 (Access: Open)
: Details in the research portal "Research@Leibniz University"

BibTeX

@article{8ddf604cf6584b33a87dda4e63ceff3f,
title = "Postglacial gravity change in Fennoscandia: Three decades of repeated absolute gravity observations",
abstract = "For the first time, we present a complete, processed compilation of all repeated absolute gravity (AG) observations in the Fennoscandian postglacial land uplift area and assess their ability to accurately describe the secular gravity change, induced by glacial isostatic adjustment (GIA). The data set spans over more than three decades and consists of 688 separate observations at 59 stations. Ten different organizations have contributed with measurements using 14 different instruments. The work was coordinated by the Nordic Geodetic Commission (NKG). Representatives from each country collected and processed data from their country, respectively, and all data were then merged to one data set. Instrumental biases are considered and presented in terms of results from international comparisons of absolute gravimeters. From this data set, gravity rates of change (ġ) are estimated for all stations with more than two observations and a timespan larger than 2 yr. The observed rates are compared to predicted rates from a global GIA model as well as the state of the art semi-empirical land uplift model for Fennoscandia, NKG2016LU. Linear relations between observed ġ and the land uplift, ḣ (NKG2016LU) are estimated from the AG observations by means of weighted least squares adjustment as well as weighted orthogonal distance regression. The empirical relations are not significantly different from the modelled, geophysical relation ġ=0.03-0.163(±0.016) ḣ. We also present a ġ-model for the whole Fennoscandian land uplift region. At many stations, the observational estimates of ġ still suffer from few observations and/or unmodelled environmental effects (e.g. local hydrology). We therefore argue that, at present, the best predictions of GIA-induced gravity rate of change in Fennoscandia are achieved by means of the NKG2016LU land uplift model, together with the geophysical relation between ġ and ḣ.",
keywords = "Dynamics of lithosphere and mantle, Europe, Geodetic instrumentation, Reference systems, Time variable gravity",
author = "Olsson, {Per Anders} and Kristian Breili and Vegard Ophaug and Holger Steffen and Emil Nielsen and T{\~o}nis Oja and Ludger Timmen and M. Bilker",
note = "Funding Information: We would like to express our thanks to all organizations and all people that contributed with absolute gravity observations over the years. Besides the organizations represented by the authors we would especially like to thank BKG and NOAA which took part in the beginning of the project and contributed with valuable early observations. Thank you, for your important contributions, Linda Alm, Ove Christian Dahl Omang, Fredrik Dahlstr{\"o}m, Bj{\o}rn Engen, Andreas Engfeldt, Reinhard Falk, Ren{\'e} Forsberg, Christian Gerlach, Olga Gitlein, Walter Hoppe, Fred Klopping, G{\'e}za Lohasz, Dagny Iren Lysaker, J{\"u}rgen M{\"u}ller, Jaakko M{\"a}kinen, Jyri N{\"a}r{\"a}nen, Are Jo N{\ae}ss, Jon Glenn Omholt Gjevestad,Bj{\o}rn Ragnvald Pettersen,Gunnar Regevik, Andreas Reinhold, Erik Roland, Hannu Ruotsalainen, Knut R{\o}thing, Glenn Sasagawa, Hans-Georg Scherneck, Marcin Sekowski, Gabriel Strykowski, Runar Svensson, Herbert Wilmes, Walter Z{\"u}rn, Jonas {\AA}gren, Ola Ovstedal and all others that in one way or the other contributed to this work. We are also grateful toMichel van Camp and Hartmut Wziontek, whose reviews have greatly helped in improving our manuscript.",
year = "2019",
month = jan,
day = "30",
doi = "10.1093/gji/ggz054",
language = "English",
volume = "217",
pages = "1141--1156",
journal = "Geophysical journal international",
issn = "0956-540X",
publisher = "Oxford University Press",
number = "2",
}