TY - JOUR

T1 - Postglacial gravity change in Fennoscandia

T2 - Three decades of repeated absolute gravity observations

AU - Olsson, Per Anders

AU - Breili, Kristian

AU - Ophaug, Vegard

AU - Steffen, Holger

AU - Nielsen, Emil

AU - Oja, Tõnis

AU - Timmen, Ludger

AU - Bilker, M.

N1 - 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 Dahlström, Bjørn Engen, Andreas Engfeldt, Reinhard Falk, René Forsberg, Christian Gerlach, Olga Gitlein, Walter Hoppe, Fred Klopping, Géza Lohasz, Dagny Iren Lysaker, Jürgen Müller, Jaakko Mäkinen, Jyri Näränen, Are Jo Næss, Jon Glenn Omholt Gjevestad,Bjørn Ragnvald Pettersen,Gunnar Regevik, Andreas Reinhold, Erik Roland, Hannu Ruotsalainen, Knut Røthing, Glenn Sasagawa, Hans-Georg Scherneck, Marcin Sekowski, Gabriel Strykowski, Runar Svensson, Herbert Wilmes, Walter Zürn, Jonas Ågren, 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.

PY - 2019/1/30

Y1 - 2019/1/30

N2 - 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.

AB - 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.

KW - Dynamics of lithosphere and mantle

KW - Europe

KW - Geodetic instrumentation

KW - Reference systems

KW - Time variable gravity

UR - http://www.scopus.com/inward/record.url?scp=85062459444&partnerID=8YFLogxK

U2 - 10.1093/gji/ggz054

DO - 10.1093/gji/ggz054

M3 - Article

AN - SCOPUS:85062459444

VL - 217

SP - 1141

EP - 1156

JO - Geophysical journal international

JF - Geophysical journal international

SN - 0956-540X

IS - 2

ER -