HR: 1340h
AN: G33A-0912    [Abstracts]
TI: Global GPS Data Analysis at the National Geodetic Survey
AU: Kass, W H
EM: bill.kass@noaa.gov
AU: Dillinger, W H
EM: william.h.dillinger@noaa.gov
AU: Dulaney, R L
EM: bob.dulaney@noaa.gov
AU: * Griffiths, J
EM: jake.griffiths@noaa.gov
AU: Hilla, S
EM: steve.hilla@noaa.gov
AU: Ray, J
EM: jim.ray@noaa.gov
AU: Rohde, J R
EM: jim.rohde@noaa.gov
AB: NOAA's National Geodetic Survey (NGS) has been one of the Analysis Centers (ACs) of the International GNSS Service (IGS) since its inception in 1994. Solutions for daily GPS orbits and Earth orientation parameters are regularly contributed to the IGS Rapid and Final products, as well as for weekly station positions. These are combined with those of the other ACs and distributed to users. The IGS realization of the International Terrestrial Reference Frame is derived from the time series of combined AC weekly frames. To perform this task, NGS has developed and refined the Program for the Adjustment of GPS EphemerideS (PAGES) software. Although PAGES has continuously evolved over the past 15 years, recent efforts have focused mostly on updating models and procedures to conform more closely to IGS conventions. Particularly significant was the IGS change in November 2006 to absolute antenna calibrations models, including ground and satellites as well as recognizing antenna radomes. Other modifications include updates from the IERS Conventions (mostly for geophysical effects and tropospheric delay) and adoption of the modified CODE orbit model (six position and velocity parameters, midday velocity breaks, and five nuisance radiation pressure parameters). Some processing strategies have also been revised to simplify and strengthen the least-squares adjustment framework, such as applying Delaunay triangulation to construct the global double-differenced baseline network. Elevation-dependent weighting of phase observations is now employed. The net result of all changes has been a major improvement during the past year in the NGS performance, compared to other IGS ACs, for almost all products generated. Details of our processing updates and demonstrations of the improvements will be provided. Issues still requiring attention and NGS plans for future developments will be reviewed.
DE: 1229 Reference systems
DE: 1241 Satellite geodesy: technical issues (6994, 7969)
DE: 1294 Instruments and techniques
DE: 1295 Integrations of techniques
DE: 1299 General or miscellaneous (1709)
SC: Geodesy [G]
MN: 2007 Fall Meeting