M.(2006): Environmental loading effects on GPS time series, this issue

Metsähovi is a permanent GPS-station in Finland. It is situated on the south coast, with the distance to the Baltic Sea being only 15 km. The effect of tidal loading is small since its distance to the ocean is 800-1000 km, therefore the other loading effects can be seen more clearly. We have studied the effects of non-tidal loading of the Baltic Sea and loading caused by atmospheric pressure and water storages on solid Earth in the height time series of GPS. When all known factors are taken into account, the variance in the GPS height time series diminishes up to 31%. Regression coefficients for the different factors were found to be –0.2 mm/hPa for the local air pressure,-9 mm/m for the nearby tide gauge recording and-0.05 mm/mm for the total water storage of Finland. The effect of local aquifers and global soil moisture need to be studied more carefully, because all the water storages correlate and give therefore similar results