HR: 1340h
AN: G43B-1206    [Abstracts]
TI: Using GPS-Derived Vertical Movements For Studies of Crustal Loading on Fennoscandian Shield
AU: * Nordman, M
EM: maaria.nordman@fgi.fi
AF: Finnish Geodetic Institute, P.O. Box 15, Masala, 02431, Finland
AU: Virtanen, H
EM: heikki.virtanen@fgi.fi
AF: Finnish Geodetic Institute, P.O. Box 15, Masala, 02431, Finland
AU: Bilker-Koivula, M
EM: mirjam.bilker@fgi.fi
AF: Finnish Geodetic Institute, P.O. Box 15, Masala, 02431, Finland
AB: The surface of the Earth is constantly being deformed by temporally and spatially varying loads of atmospheric, oceanic and hydrological masses. These deformations are detectable in the height component of GPS time series. We have studied the loading effect using GPS-derived vertical movements for three stations on Fennoscandian shield, Metsähovi, Onsala and Bor\rmås. Three loading factors that are not yet routinely implemented in the GPS calculations have been assessed, namely loading caused by air pressure variation, by non-tidal sea level changes and by changes in the continental water reservoirs. The effect of continental water was studied using two global soil moisture models. Air pressure data was taken from a local barometer in Metsähovi and from the numerical weather model HIRLAM (High Resolution Limited Area Model) for the stations Onsala and Bor\rmås. Sea level data was obtained from the nearest tide gauges. Multilinear regression analysis was used for air pressure and sea level changes. The loading factors are compared with the vertical motion observed by GPS for a time period of 4 years 8 months. The results show that the amplitude of the annual signal varies from 4.0 mm at Metsähovi to 1.2 mm at Borås. The correction for the soil moisture seems to remove part of the annual signal. When all the factors are considered, the variance of the GPS time series diminishes by 40% for Metsähovi, 24% for Onsala and 15% for Bor\rmås. The regression coefficients for the air pressure were -0.32 mm/hPa for Metsähovi, -0.27 mm/hPa for Onsala and -0.25 mm/hPa for Bor\rmås. The coefficients for the sea level height were -6 mm/m, -8 mm/m and -5 mm/m, respectively. The reduction of the loading phenomena dimishes the scatter of the GPS time series. The loading corrections could be used for several purposes, e.g. for the studies of other error sources, to create stable time series and also to correct for campaign measurements, which take place in varying weather conditions.
DE: 1211 Non-tectonic deformation
DE: 1223 Ocean/Earth/atmosphere/hydrosphere/cryosphere interactions (0762, 1218, 3319, 4550)
DE: 1240 Satellite geodesy: results (6929, 7215, 7230, 7240)
DE: 1295 Integrations of techniques
DE: 9335 Europe
SC: Geodesy [G]
MN: 2007 Fall Meeting