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

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

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

4. SRI Seminar 2005 Time Series Coordinates derived from controlled adjustments (orbits fixed) l X,Y,Z transformed to φ, λ, h Differences in N(orth), E(ast), U(p) l 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)

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

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

7. SRI Seminar 2005 IGS station map

8. SRI Seminar 2005 EPN station map

9. SRI Seminar 2005 IGS station velocity map

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

11. SRI Seminar 2005 Example Bahrain ITRF2000 (1995-1999)

12. SRI Seminar 2005 Example Bahrain ITRF2000 short term NorthEast Up

13. SRI Seminar 2005 Example Graz ITRF2000

14. SRI Seminar 2005 Example Ankara ETRS89 reference jumps removed

15. SRI Seminar 2005 Example Graz ETRS89 detrended + reference jumps removed

16. SRI Seminar 2005 Example Ankara ETRS89 detrended + reference jumps removed

17. SRI Seminar 2005 Earthquake Signal Earthquake shift some decimeters

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

19. SRI Seminar 2005 Equipment Effects

20. SRI Seminar 2005 Periodic Effects

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

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

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

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

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

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

27. SRI Seminar 2005 Interpolation (1) Stress Field

28. SRI Seminar 2005 Interpolation (2) Strain Field

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

30. SRI Seminar 2005 Spectral Analysis (1) Autocorrelation

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

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

33. SRI Seminar 2005 We will continue Thank You!