HR: 08:55h
AN: G21B-04    [Abstracts]
TI: Mapping of GPS Networks Into ITRF: Regional Versus Global Approach
AU: * Fernandes, R M
EM: rui@deos.tudelft.nl
AF: DEOS - Department of Earth Observation and Space Systems, TU Delft, Kluyverweg, 1, Delft, 2629 HS Netherlands
AU: * Fernandes, R M
EM: rui@deos.tudelft.nl
AF: DI - Department of Science Computers, UBI, R. Marques d'Avila e Bolama, Covilh\~{a}, 6201-001 Portugal
AU: Ambrosius, B A
EM: B.A.C.Ambrosius@lr.tudelft.nl
AF: DEOS - Department of Earth Observation and Space Systems, TU Delft, Kluyverweg, 1, Delft, 2629 HS Netherlands
AU: Noomen, R
EM: Ron.Noomen@deos.tudelft.nl
AF: DEOS - Department of Earth Observation and Space Systems, TU Delft, Kluyverweg, 1, Delft, 2629 HS Netherlands
AU: Bastos, L
EM: lcbastos@fc.up.pt
AF: OAUP - Astronomical Observatory, University of Porto, Monte da Virgem, V. N. Gaia, 4430-146 Portugal
AU: Becker, M
EM: matthias.becker@unibw-muenchen.de
AF: Institute for Geodesy, University of the Bundeswehr Munich, Neubiberg, Neubiberg, 85577 Germany
AB: To align daily (or combined) GPS solutions with any realization of the International Referential Reference System (currently, ITRF2000), the usual first requirement is to process the network of interest together with a subset of stations with well-known position and velocity estimates in ITRF2000. These reference stations are then used to compute the transformation parameters to project the daily (or combined) "unknown" reference frame onto ITRF2000. The selection of the reference stations is a fundamental step of the mapping process. Although ITRF2000 is a large improvement (quality, quantity) in comparison with the previous ITRF versions, the amount and distribution of GPS stations (typically IGS stations) with well-determined ITRF2000 position/velocity representation is still not optimal. The problem is significant for many regions since more than two-thirds of the reliable IGS stations are located in Europe and North America). Regional networks of GPS stations (located on the North Atlantic and European areas) are used to discussed several issues related with the selection of the best set of reference stations for the mapping of episodic and permanent networks. Special attention is dedicated to the choice between a regional (continental size) and a global mapping approach. Based on several tests carried out, the selection of a global reference network is favored over a regional set of mapping stations. The tests show that a regional approach does not provide a significant improvement for the specific network locally. Moreover, the global approach is more consistent with ITRF2000 on a planetary scale (although the scope is restricted to a North Atlantic - European scale). For the analyzed permanent networks, the small number and uneven distribution of reliable IGS stations, within and around them, also favor the use of a global network to estimate the mapping parameters. The possibility of extrapolating existing errors in the transformation parameters also supports this option.
DE: 1243 Space geodetic surveys
DE: 1247 Terrestrial reference systems
SC: Geodesy [G]
MN: 2004 AGU Fall Meeting