Postglacial gravity change in Fennoscandia – three decades of repeated absolute gravity observations

Research output: Research - peer-reviewJournal article – Annual report year: 2019

DOI

  • Author: Olsson, Per-Anders

    Swedish mapping, cadastral and land registration authority, Sweden

  • Author: Breili, Kristian

    The Norwegian Mapping Authority, Norway

  • Author: Ophaug, Vegard

    Norwegian University of Life Sciences, Norway

  • Author: Steffen, Holger

    Swedish mapping, cadastral and land registration authority, Sweden

  • Author: Bilker-Koivula, Mirjam

    National Land Survey of Finland, Finland

  • Author: Nielsen, Emil

    Geodynamics, National Space Institute, Technical University of Denmark, Elektrovej, 2800, Kgs. Lyngby, Denmark

  • Author: Oja, Tõnis

    Estonian Land Board, Estonia

  • Author: Timmen, Ludger

    Leibniz Universität Hannover, Germany

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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 dataset spans over more than three decades and consists of 688 separate observations at 59 stations. Ten different organisations have contributed with measurements using 14 different instruments. The work was coordinated by the Nordic Geodetic Commisson (NKG). Representatives from each country collected and processed data from their country, respectively, and all data were then merged to one dataset. Instrumental biases are considered and presented in terms of results from international comparisons of absolute gravimeters. From this dataset, gravity rates of change (⁠g˙⁠) are estimated for all stations with more than two observations and a timespan larger than two years. 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 g˙ and the land uplift, h˙ (NKG2016LU), are estimated from the absolute gravity observations by means of weighted least squares adjustment (WLSA) as well as weighted orthogonal distance regression (WODR). The empirical relations are not significantly different from the modelled, geophysical relation g˙=0.03−0.163(±0.016)h˙⁠. We also present a g˙-model for the whole Fennoscandian land uplift region. At many stations, the observational estimates of g˙ 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 g˙ and h˙⁠.
Original languageEnglish
JournalGeophysical Journal International
ISSN0956-540X
DOIs
StateAccepted/In press - 2019
CitationsWeb of Science® Times Cited: No match on DOI

    Research areas

  • Time variable gravity, Geodesy and gravity, Geodetic instrumentation, Reference systems, Dynamics of lithosphere and mantle, Europe
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