HR: 17:15h
AN: G24A-06    [Abstracts]
TI: New displacement values of the Fennoscandia GIA process from BIFROST
AU: * Lidberg, M
EM: lidberg@oso.chalmers.se
AF: Chalmers University of Tecknology, Onsala Space Observatory, Onsala, 43992 Sweden
AU: Johansson, J M
EM: jmj@oso.chalmers.se
AF: Chalmers University of Tecknology, Onsala Space Observatory, Onsala, 43992 Sweden
AU: Scherneck, H
EM: hgs@oso.chalmers.se
AF: Chalmers University of Tecknology, Onsala Space Observatory, Onsala, 43992 Sweden
AU: Haas, R
EM: haas@oso.chalmers.se
AF: Chalmers University of Tecknology, Onsala Space Observatory, Onsala, 43992 Sweden
AB: We present a new improved 3D velocity field of the Fennoscandian Glacial Isostatic Adjustment (GIA) process derived from more than 3000 days at more than 50 permanent GPS sites. We use the GAMIT/GLOBK and the GIPSY/OASIS II software packages for GPS analysis. We compare the results from GAMIT/GLOBK, from GIPSY in PPP mode (Precise Point Positioning), and from GIPSY with ambiguity fixing. The solution has an internal accuracy at the level of 0.2 mm/yr (1 sigma) for horizontal velocities at the best sites. Our vertical velocities agree with results derived from classic geodetic methods (tide-gauge, repeated levellings, repeated gravity observations, and an estimated sea level rise of 1.2 mm/yr) at the 0.5 mm/yr level (1 sigma). We also compare our GPS derived velocities with results from VLBI at Onsala, Wettzell, Ny-�lesund, and Svetloe. Our results also agree with values from a GIA prediction model at the 1mm/yr level. However, the new velocity solution arrives at slightly smaller vertical velocities especially in the central region with largest land uplift, and smaller horizontal velocities for sites in the outher region. This prompts for a reiteration of the GIA model where also the ice history could be considered at greater detail. In the presentation we will address the problem of stability of the geodetic reference frame, which is crucial e.g. while comparing results from space geodetic methods and tide gauges to study sea level change.
DE: 1222 Ocean monitoring with geodetic techniques (1225, 1641, 3010, 4532, 4556, 4560, 6959)
DE: 1229 Reference systems
DE: 1240 Satellite geodesy: results (6929, 7215, 7230, 7240)
DE: 1241 Satellite geodesy: technical issues (6994, 7969)
DE: 1243 Space geodetic surveys
SC: Geodesy [G]
MN: Fall Meeting 2005