HR: 17:30h
AN: G34A-07    [Abstracts]
TI: A Comparison of Vertical Land Movement Estimates at Tide Gauges: CGPS, Absolute Gravimetry and Independent Evidence Compared
AU: Bingley, R M
EM: richard.bingley@nottingham.ac.uk
AF: Institute of Engineering Surveying and Space Geodesy, University of Nottingham, University Park, Nottingham, NG7 2RD United Kingdom
AU: * Teferle, F N
EM: norman.teferle@nottingham.ac.uk
AF: Institute of Engineering Surveying and Space Geodesy, University of Nottingham, University Park, Nottingham, NG7 2RD United Kingdom
AU: Williams, S D
EM: sdwil@pol.ac.uk
AF: Proudman Oceanographic Laboratory, Joseph Proudman Building, 6 Brownlow Street, Liverpool, L3 5DA United Kingdom
AU: Baker, T F
EM: tfb@pol.ac.uk
AF: Proudman Oceanographic Laboratory, Joseph Proudman Building, 6 Brownlow Street, Liverpool, L3 5DA United Kingdom
AB: In this presentation we investigate the use of a combination of continuous GPS (CGPS) and absolute gravimetry (AG) in order to infer estimates of vertical land movements at tide gauges of the European Sea Level Service (ESEAS). CGPS estimates of land emergence/submergence rates are known to be dependent on the CGPS processing strategy, the reference frame and its realization in a particular analysis. The processing-specific effect on the vertical rate estimates stem from, e.g. the choice of satellite orbit and clock products, the processing method, i.e. double difference and precise point positioning, and the modeling of satellite and receiver antenna phase center corrections. Besides these, the accuracy and long-term stability of the International Terrestrial Reference Frame, ITRF2000, is limited. Furthermore, the CGPS estimates of land emergence/submergence rates are largely dependent on the subset of global ITRF stations used in any particular analysis. It is generally believed that CGPS can only be used to infer differential land motions. In contrast to this, land emergence/submergence rates from AG measurements are largely independent of reference frames and are not affected by issues such as antenna phase center modeling. As can be seen from many examples, if carried out with appropriate care, AG measurements are capable of delivering highly accurate estimates of land emergence/submergence when used annually over several days after five to ten years. Using the emergence/submergence rates from several different CGPS analyses and AG obtained by the ESEAS-Research Infrastructure (ESEAS-RI) project, we then carry out a comparison with independent evidence for vertical land movements in Europe. This independent evidence includes mean sea level records from ESEAS tide gauges, geological evidence if available, and results from glacial isostatic adjustment models. An offset of the CGPS estimates from the AG estimates can be computed for each CGPS solution. This offset can then be verified using the available information for a particular site.
DE: 1225 Global change from geodesy (1222, 1622, 1630, 1641, 1645, 4556)
DE: 1243 Space geodetic surveys
DE: 1295 Integrations of techniques
DE: 1641 Sea level change (1222, 1225, 4556)
SC: Geodesy [G]
MN: Fall Meeting 2005