National Report of Sweden to the NKG General ... - Lantmäteriet

9Lantmäteriet has since 2007 madein the future (with standard uncertainty26GIA = Glacial Isostatic Adjustmentof the order 5 mm). Two preliminaryconclusions from this ongoing project(not yet published) are that a newgravity system is needed and that 5 kmresolution is sufficient for the detailgravity. Besides, a significant amount ofnew observations are required and theabsolute observations with the newinstrument on 12 of the Swedish sites,but also on 1 Danish site, 1 Finnish site,2 Norwegian sites, 3 Serbian sites andat two inter-comparisons (one with 19other gravimeters in Luxembourg andone with 22 other gravimeters in Paris).old data need to be checked andupdated in various ways.All Swedish sites are co-located withpermanent reference stations for GNSSin the SWEPOS network (except for1.9 GravimetryGöteborg which is no longer in use).The number of Swedish sites whereOnsala is also co-located with VLBI 27 .absolute gravity observations haveSkellefteå, Smögen, and Visby are colocatedwith tide gauges.been carried out has increased from 11to 14 sites since the last NKG General The absolute gravity observations areAssembly, see Figure 1.10.co-ordinated within NKG, andIn the autumn of 2006, Lantmäterietobservations have also been performedpurchased a new absolute gravimeterby several groups (BKG 28 , IfE 29 , UMB 30(Micro-g Lacoste FG 5 - 233), see Figureand FGI 31 ) together with Lantmäteriet.1.9. The objective behind thisThis arrangement has made it possibleinvestment is to ensure and strengthento observe 7 of the sites every year sincethe observing capability for long term2003 (marked with green backgroundmonitoring of the changes in thecircles in Figure 1.10).gravity field due to the FennoscandianGIA 26 .Figure 1.9: The new FG5 absolutegravimeter and the observer team duringthe on-site training course. Photo: Mikael 27VLBI= Very Long Baseline InterferometryLilje.28BKG = Bundesamt für Kartographie und Geodäsie,Germany29IfE = Institut für Erdmessung, Universität Hannover,Germany30UMB = Universitetet for Miljø og Biovitenskap, Norway31FGI = Finnish Geodetic Institute, Finland