HR: 0800h
AN: G31A-0782    [Abstracts]
TI: Tropospheric Parameters and Subdaily EOP From Combinations of Independent Space Geodetic Data
AU: Thaller, D
EM: daniela.thaller@bv.tum.de
AF: Forschungseinrichtung Satellitengeod\"asie, TU Munich, Arcisstrasse 21, Munich, D-80290 Germany
AU: Kr\"ugel, M
EM: kruegel@dgfi.badw.de
AF: Deutsches Geod\"atisches Forschungsinstitut, Marstallplatz 8, Munich, D-80539 Germany
AU: * Rothacher, M
EM: rothacher@bv.tum.de
AF: Forschungseinrichtung Satellitengeod\"asie, TU Munich, Arcisstrasse 21, Munich, D-80290 Germany
AU: Angermann, D
EM: angerman@dgfi.badw.de
AF: Deutsches Geod\"atisches Forschungsinstitut, Marstallplatz 8, Munich, D-80539 Germany
AU: Schmid, R
EM: ralf.schmid@bv.tum.de
AF: Forschungseinrichtung Satellitengeod\"asie, TU Munich, Arcisstrasse 21, Munich, D-80290 Germany
AU: Tesmer, V
EM: tesmer@dgfi.badw.de
AF: Deutsches Geod\"atisches Forschungsinstitut, Marstallplatz 8, Munich, D-80539 Germany
AB: The space geodetic techniques GPS, VLBI, SLR and DORIS contribute to the determination of several geodetic parameters (e.g. site positions, Earth orientation parameters (EOP), tropospheric parameters) providing valuable information to study various geophysical processes. Due to the different strengths of the techniques it can be expected that the parameters benefit from a combination. The VLBI campaign CONT02, initiated by the IVS, provides 15~days of continuous VLBI measurements. Therefore, this data set is well-suited for the combination with other techniques. Especially the combination with other microwave techniques like GPS provides the opportunity to estimate common tropospheric parameters in addition to station coordinates and EOP. For the studies presented here, free daily normal equations were generated for GPS and VLBI using identical models and the same parameterization to avoid any inconsistencies. Additionally, the normal equation of a 14-day SLR solution is included to investigate primarily reference frame related aspects. The work focusses on the combination of tropospheric parameters and EOP with a high resolution in time: solutions with one and two hour resolution of the parameters were compared to decide whether a higher time resolution is more appropriate to describe the time-dependent behavior of these parameters. For the validation of the tropospheric parameters independent data sets of water vapor radiometers are used, and the EOP are compared with a subdaily model derived from altimetry. Special attention has to be addressed to the tropospheric parameters from GPS, because they are sensitive to the physical characteristics of the antenna and the antenna environment. The comparison with VLBI-derived tropospheric parameters shows that absolute antenna phase center corrections should be used instead of relative models. Similarly, if a radome is installed at the antenna, the tropospheric zenith delay estimates change significantly. As no phase center calibrations are available for antenna/radome configurations, this effect limitates the benefit to be achieved by a combination. However, the results show, that a rigorous combination improves the quality of all estimated parameters compared to the single technique solutions. In addition to the microwave techniques, SLR normal equations were included in the combination studies as well, but only with a daily resolution for the ERP. The advantage of SLR must be seen in the contribution to a more stable definition of the reference system due to more co-located stations and a better realization of the geocenter. Furthermore, SLR can deliver valuable information for the scale of the combined network.
DE: 1210 Diurnal and subdiurnal rotational variations
DE: 1229 Reference systems
DE: 1243 Space geodetic surveys
DE: 1247 Terrestrial reference systems
SC: Geodesy [G]
MN: 2004 AGU Fall Meeting