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Time series of GPS stations

Time series of GPS stations. Günter Stangl Federal Office of Metrology and Surveying. For reference, monitoring and geophysics. Some Definitions. GPS = Global Positioning System 2 Frequencies (Between 1-2 GHz) Phase measurements (L1,L2) for precise determination, resolution about 0.5 mm

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Time series of GPS stations

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  1. Time series of GPS stations Günter Stangl Federal Office of Metrology and Surveying For reference, monitoring and geophysics SRI Seminar 2005

  2. Some Definitions • GPS = Global Positioning System • 2 Frequencies (Between 1-2 GHz) • Phase measurements (L1,L2) for precise determination, resolution about 0.5 mm • Equipment antennas+receivers • Post processing for high accuracy SRI Seminar 2005

  3. Some more Definitions • ITRS = International Terrestrial Reference System (Earth fixed system) • ITRF = Representation of ITRS, updated sometimes, presently ITRF2000 (epoch 1997.0), combined solution of VLBI, SLR, GPS and DORIS measurements • ETRS89 = European Terrestrial Reference System (Fixed to the “stable“ part of Eurasia, defined 1989), plate velocity removed, “constant” coordinates • ETRF = Representation of ETRS, derived from ITRF by GPS, Helmert transformation applied SRI Seminar 2005

  4. Time Series • Coordinates derived from controlled adjustments (orbits fixed) • X,Y,Z transformed to φ, λ, h • Differences in N(orth), E(ast), U(p) • Neglecting correlations in space and time • Restricted to permanent stations • Total zenith delays for climatology (In Europe standardized) • Main target: station velocities (needed for ITRF definition) • Additional use for station monitoring (jumps) and geodynamics (plate motions) SRI Seminar 2005

  5. Different Reference Frames Different Antenna Definitions Modeling Errors Seasonal Variations Site Problems (Equipment, Monumentation, Atmosphere) Orbits and Clocks before 1992 Orbits and Clocks 1992-2004 Different Adjustments About 20 mm About 10 mm About 5 mm Up to 10 mm Up to 30 mm Height 60 mm About 50 mm Up to 30 mm Up to 20 mm Systematic effects on station coordinates SRI Seminar 2005

  6. Removing procedures • Reference frame transformation (identical sites) • Recomputation with calibrated antenna values • Recomputation with corrected orbits • Combined adjustment solutions • Detrending (velocities) SRI Seminar 2005

  7. IGS station map SRI Seminar 2005

  8. EPN station map SRI Seminar 2005

  9. IGS station velocity map SRI Seminar 2005

  10. NUVEL (2D) Plate Motions derived from geology SRI Seminar 2005

  11. Example BahrainITRF2000 (1995-1999) SRI Seminar 2005

  12. Example BahrainITRF2000 short term North East Up SRI Seminar 2005

  13. Example GrazITRF2000 SRI Seminar 2005

  14. Example AnkaraETRS89 reference jumps removed SRI Seminar 2005

  15. Example GrazETRS89 detrended + reference jumps removed SRI Seminar 2005

  16. Example AnkaraETRS89 detrended + reference jumps removed SRI Seminar 2005

  17. Earthquake Signal Earthquake shift some decimeters SRI Seminar 2005

  18. Pseudo-Earthquake Signal Receiver change and earthquake nearby SRI Seminar 2005

  19. Equipment Effects SRI Seminar 2005

  20. Periodic Effects SRI Seminar 2005

  21. Examples from Austria + 20 stations from Germany, Slovenia, Switzerland + 5 new stations/year SRI Seminar 2005

  22. HFLK (Hafelekar ) Monumentation in bedrock • Permanent since October 1994, constructed by ZAMG Wien • 1994: Minirogue • 1997: Turborogue • 1999: Trimble • Software: Terrasat • Permanentstation for: • IGS since 1994 • EPN since 1996 • APOS RTK since 2004 SRI Seminar 2005

  23. RTMN (Rottenmann) Monumentation on building • Permanent since September 1999; financed by city of Rottenmann • 9/1999: Trimble • 11/1999: Z-18 • Software: Terrasat SRI Seminar 2005

  24. Local Effects (1) Danube Alluvium Gradual sinking SRI Seminar 2005

  25. Local Effects (2) Rock instability Overlay of seasonal (frost) and rock gliding effects ? (Station height 3 600 m) SRI Seminar 2005

  26. Human Errors and Strange Effects My failure wrong antenna type ? Probably Snow/Ice But wrong direction SRI Seminar 2005

  27. Interpolation (1)Stress Field SRI Seminar 2005

  28. Interpolation (2)Strain Field SRI Seminar 2005

  29. Summary Space Domain • Remove outliers and movements for reference determination • Remove outliers and reference jumps for velocity estimation • Remove outliers, reference jumps and known global velocities for regional (intraplate) motions • Remove all known features and you‘ll find new ones (?) • Which colour has the noise? SRI Seminar 2005

  30. Spectral Analysis (1)Autocorrelation SRI Seminar 2005

  31. Spectral Analysis (2)Power spectrum GRAZ SRI Seminar 2005

  32. Summary Frequency Domain • You can have white noise coordinates! • Possible sources of non-white noise: • - Receiver misbehaviour (Channels) • - Adjustment procedures (models, orbits) • - Monumentation (temperature, ice) • - Underground (´water level) • - Unmodelled weather effects (Foehn) SRI Seminar 2005

  33. We will continueThank You! SRI Seminar 2005

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