Continuous GPS measurements of postglacial adjustment in Fennoscandia - 1. Geodetic results
Journal article, 2002

Project BIFROST (Baseline Inferences for Fennoscandian Rebound Observations, Sea-level, and Tectonics) combines networks of continuously operating GPS receivers in Sweden and Finland to measure ongoing crustal deformation due to glacial isostatic adjustment (GIA). We present an analysis of data collected between August 1993 and May 2000. We compare the GPS determinations of three-dimensional crustal motion to predictions calculated using the high-resolution Fennoscandian deglaciation model recently proposed by Lambeck et al. [1998a, 1998b]. We find that the maximum observed uplift rate (~10 mm/yr) and the maximum predicted uplift rate agree to better than 1 mm yr-1. The patterns of uplift also agree quite well, although significant systematic differences are evident. The root-mean-square residual rate for a linear error model yields estimates of rate accuracy of 0.4 mm/yr for east, 0.3 mm/yr for north, and 1.3 mm/yr for up; these figures incorporate model errors, however. We have also compared the values for the observed radial deformation rates to those based on sea level rates from Baltic tide gauges. The observational error for the vertical GPS rates required to give a reduced chi^2 of unity is 0.8 mm/yr. The time series do exhibit temporal variations at seasonal frequencies, as well as apparent low-frequency noise. An empirical orthogonal function analysis indicates that the temporal variations are highly correlated among the sites. The correlation appears to be regional and falls off only slightly with distance. Some of this correlated noise is associated with snow accumulation on the antennas or, for those antennas with radomes, on the radomes. This problem has caused us to modify the radomes used several times, leading to one of our more significant sources of uncertainty.

Vertical motion

Sea level change

Glacial isostacy Space geodesy


Jan Johansson

Chalmers, Department of Radio and Space Science

James L. Davis

Hans-Georg Scherneck

Chalmers, Department of Radio and Space Science

Glenn A. Milne

Martin Vermeer

Jerry X. Mitrovica

Richard A. Bennett

Bo Jonsson

Gunnar Elgered

Chalmers, Department of Radio and Space Science

Pedro Elósegui

Hannu Koivula

Markku Poutanen

Bernt Rönnäng

Chalmers, Onsala Space Observatory

Chalmers, Department of Radio and Space Science

Irvin I. Shapiro

Journal of Geophysical Research

01480227 (ISSN) 21562202 (eISSN)

Vol. 107 B8


Basic sciences


Onsala Space Observatory

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