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Status of ITRF Development and SLR Contribution

Explore the current state of ITRF development and SLR contribution, focusing on vertical velocities and GIA modeling. Preliminary analysis, including official and non-official solutions, outlines the importance of stable, long-term ITRF parameters with no discontinuity. Review the origin, scale, and analyzed solutions with emphasis on maintaining intrinsic conditions and preserving SLR origin and scale. Assess the impact of network shapes, origins, and scale on vertical velocities. ##

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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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