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Status of ITRF Development and SLR Contribution

Status of ITRF Development and SLR Contribution. Key Word: Vertical Velocities and GIA. Zuheir Altamimi Xavier Collilieux David Coulot IGN France. Warning. Preliminary analysis SLR Analyzed Solutions are not official ILRS products ILRS reprocessed combined solution not yet available.

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Status of ITRF Development and SLR Contribution

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  1. Status of ITRF Development and SLR Contribution Key Word: Vertical Velocities and GIA Zuheir Altamimi Xavier Collilieux David Coulot IGN France

  2. Warning • Preliminary analysis • SLR Analyzed Solutions are not official ILRS products • ILRS reprocessed combined solution not yet available

  3. Outline • Focus on SLR contribution • Origin & Scale • Vertical Velocities & GIA model (?) • Analyzed solutions: • IVS official combined time series • ASI-12 • GRGS-11 • NCL (Philip Moore): Not yet an Official ILRS AC • Test SLR solutions (David Coulot): • Solution per satellite (L1 & L2)

  4. ITRF and Science Requirement • Long-term stable ITRF: 0.1 mm/yr • Stable: linear behaviour of the TRF parameters, i.e. with no discontinuity : • Origin Components: 0.1 mm/yr • Scale 0.01 ppb/yr (0.06 mm/yr) • Current situation: probably not better than 1 mm/yr

  5. Current ITRF Derivation Step 1 S1 S2 S3 … Sn VLBI TRF (X, V)+ EOP (SINEX) W1 W2 … Wn SLR TRF (X, V)+ EOP (SINEX) Stacking W1 W2 … Wn GPS TRF (X, V)+ EOP (SINEX) W1 W2 … Wn DORIS TRF (X, V)+ EOP (SINEX) Combination ITRF Local Ties Step 2 TRF (X, V)+ EOP (SINEX)

  6. Intrinsic Conditions • Preserve the intrinsic origin of SLR • Seen as No-Net-Translation condition • Preserve/Realize the long-term CoM as sensed by SLR • Preserve the intrinsic scale of SLR & VLBI &

  7. Origin and Scale wrt ITRF2005

  8. Origin and Scale wrt ITRF2005

  9. Origin and Scale wrt ITRF2005

  10. IGN SLR Origin & Scale ITRF2005Contribution by David Coulot

  11. IGN SLR Origin & Scale ITRF2005Contribution by David Coulot 4.3 mm 1.0 mm 0.36 ppb 1.4 mm

  12. IGN SLR Origin & Scale ITRF2005Contribution by David Coulot

  13. IVS Scale (ppb) wrt ITRF2005Mean Pole Tide Corrected

  14. IVS and SLR (ASI-12) Scale (ppb) wrt ITRF2005

  15. Origin, Scale & Vertical Velocities • Vertical velocities depend on • Z-Translation rate: • Scale rate : ratio 1 to 1 • But Vertical velocities should reflect geophysics (GIA)

  16. Illustration of Origin, Scale drift on Vertical Velocities Impact of 1.8 mm/yr Tz drift (VLBI Network) Impact of -0.2 ppb/yr Scale drift (SLR Network)

  17. VLBI and SLR Co-located (with GPS) Sites Two different network shapes

  18. Peltier, ICE-5G V1.2, Earth VM4 UP velocitiesat ITRF2005 sites

  19. UP Velocitity Differences ASI-12 -IVS (ITRF2005 origin)

  20. ASI-12 UP velocities at Co-location sitesIntrinsic Origin and Scale Mean = - 0.36 mm/yr WeightedMean = - 0.24

  21. ASI-12 UP velocities & GIA correctedat Co-location Sites (Intrinsic Origin and Scale) Mean = - 0.32 mm/yr WeightedMean = +0.16

  22. IVS UP velocities at Co-location sitesIntrinsic Scale, Origin from SLR(ITRF2005) Mean = +0.96 mm/yr WeightedMean = +0.89

  23. IVS UP velocities & GIA correctedat Co-location SitesIntrinsic Scale, Origin from SLR(ITRF2005) Mean = +0.94 mm/yr WeightedMean = +1.26

  24. IVS UP velocities at Co-location sitesIntrinsic Scale, Origin from SLR(ITRF2000) Mean = +0.19 mm/yr WeightedMean = -0.24

  25. IVS UP velocities & GIA correctedat Co-location SitesIntrinsic Scale, Origin from SLR(ITRF2000) Mean = +0.18 mm/yr WeightedMean = +0.13

  26. Concluding Remarks • Preliminary analysis: to be repeated with official ILRS reprocessed solution • Vertical velocity differences ( and hence scale rate diff. ) btw IVS and ASI-12 are most likely due to: • Different network shapes to infer similar GIA effect • ITRF origin (ITRF2005 vs ITRF2000 ?) • Accuracy of vertical velocities is probably not better than 1 mm/yr • GPS/IGS dense network is useless without SLR & VLBI • Continuous observations by space techniques are fundamental • Equally fundamental is the improvement of the geodetic infrastructure

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