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The IGS 2 nd reprocessing (repro2)

The IGS contribution to ITRF2013 – Preliminary results from the IGS repro2 SINEX combinations Paul Rebischung, Bruno Garayt, Xavier Collilieux, Zuheir Altamimi AGU Fall Meeting 2014, Abstract G11C-07, San Francisco, 15 December 2014. The IGS 2 nd reprocessing (repro2).

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The IGS 2 nd reprocessing (repro2)

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  1. The IGS contribution to ITRF2013–Preliminary results from the IGS repro2SINEX combinationsPaul Rebischung, Bruno Garayt, Xavier Collilieux, Zuheir AltamimiAGU Fall Meeting 2014, Abstract G11C-07, San Francisco, 15 December 2014

  2. The IGS 2nd reprocessing (repro2) • Re-analysis of GNSS data collected by the IGS network since 1994 using the latest models and methodology • Reduce systematic errors in IGS products • Provide IGS contribution to ITRF2013 • Main updates since repro1: • Daily data integrations (instead of weekly) • GLONASS data processed by some ACs • IGb08/igs08.atx framework • IERS2010 Conventions • New yaw attitude models for eclipsing satellites • A priori modeling of Earth radiation pressure and antenna thrust • See details at: http://acc.igs.org/reprocess2.html

  3. Analysis Center submissions • Submitted products include: • Satellite orbits and clocks • Terrestrial frames and EOPs (daily SINEX files) Contributions from 7 operationalACs + 2 TIGA contributions

  4. 1st combinations (1/2) WRMS of station position residuals(i.e., of daily « AC – combined » differences) • Outlying days for several ACs: ongoing re-submissions

  5. 1st combinations (2/2) Smoothed WRMS • ULR: • Large systematic errors in East • Issue in sub-network combos • Ongoing re-submissions • GRG: • Large systematic errors in Up • Pronounced semi-annual variations in North and Up • Under investigation → 2nd combinations with GRG, ULR & GTZ included for comparison only

  6. 2nd combinations (1/2) Smoothed WRMS Smoothed, unbiased WRMS • MIT seems to dominate in Up (and North). • Because « classical » WRMS are biased in favor of ACs with non-common stations. → Use Sillard (1999)’s unbiased WRMS # stations in AC solutions

  7. 2nd combinations (2/2) Smoothed, unbiased WRMS • GFZ’sNorth WRMS vs. meanionosphere TEC: • Error in 2ndorderionospheric corrections • New productssubmitted, but stillaffected by several issues • → 3rdcombinationswith GFZ included for comparisononly ― GFZ’sNorth WRMS ― a + (b x mean_TEC)

  8. 3rd combinations Smoothed, unbiased WRMS • Inter-AC agreementafter 2004: • Horizontal: ≈ 1 – 1.5 mm • Vertical: ≈ 3 – 4 mm • Comparable to the weekly repro1 results • Substantial degradation before 2000 (and 1997) • Much less marked in repro1: 3D RMSof repro1combinationresiduals

  9. Spectral analysis Stackedperiodograms of station position residuals(computedusing stations with > 3000 days of data) • Background: flicker + white noise • Spectral peaks at: • Annual period; GPS draconitic harmonics • Fortnightly periods (14.8, 14.2, 13.7 & 13.2 d) • 9.1 d (MIT); 8.2 & 7.8 d (COD, ESA, MIT);7.0 d (MIT); 3.65 & 2.2 d (GRG) East North Up

  10. Scale AC / ig2 scale offsets • Inter-AC agreement: 0.3 – 0.5 mm • Scale rate differences < 0.1 mm/yr • Combined scale rate wrt IGb08:-0.03 mm/yr • Contribution to ITRF2013 scale rate? ig2 / IGb08 scale offsets

  11. Origin: Y component AC / ig2 Y origin offsets • Inter-AC agreement: ≈ 3 – 5 mm • nearly 10 times larger than for scale • Y component of combined origin: • Good agreement in phase with SLR • Annual amplitude slightly over-estimated ― ig2 / IGb08 Y origin offsets ― SLR / ITRF2008 Y origin offsets (cf. G11C-08)

  12. Origin: X component AC / ig2 X origin offsets • Inter-AC agreement: ≈ 3 – 5 mm • nearly 10 times larger than for scale • X component of combined origin: • Annual amplitude under-estimated • Broad spectral peak around 3.12 cpy ― ig2 / IGb08 X origin offsets ― SLR / ITRF2008 X origin offsets (cf. G11C-08)

  13. Origin: Z component AC / ig2 Z origin offsets • Inter-AC agreement: ≈ 6 – 9 mm • nearly 20 times larger than for scale • Z component of combined origin: • Spoiled by GPS draconitic harmonics • Annual signal out-of-phase with SLR ― ig2 / IGb08 Z origin offsets ― SLR / ITRF2008 Z origin offsets (cf. G11C-08)

  14. Earth Orientation Parameters AC / ig2 X-pole differences AC / ig2 Y-pole differences AC / ig2 LOD differences • Inter-AC agreement: ≈30 μas; 150-200 μas/d; 15-30 μs/d AC / ig2 X-pole rate differences AC / ig2 Y-pole rate differences WRMS of EOP residual time series

  15. Summary • Station positions: • Post-2004 inter-AC agreement comparable to weekly repro1 results • Substantially worse in early years • Scale: • Excellent inter-AC agreement • Contribution to ITRF2013 scale rate? • Origin: • No substantial improvement • EOPs: • Inter-AC agreement slightly improved compared to repro1

  16. Next steps • Expected by end of January 2015: • Re-submissions (COD, GFZ) • Extensions to 2014 (COD, ESA, MIT) • Final combined solutions due by end of February 2015 • If time allows, study stationresidual time series: • Form long-termcumulative solution • Revised discontinuity list • Modeling of post-seismicdeformations ULAB Northresiduals

  17. Thanks for your attention!

  18. Pole coordinates AC / ig2 Y-pole differences AC / ig2 X-pole differences

  19. Pole rates AC / ig2 Y-pole rate differences AC / ig2 X-pole rate differences

  20. Length of day Normalizedperiodograms AC / ig2 LOD differences

  21. Origin: X component Normalizedperiodograms AC / ig2 X origin offsets

  22. Origin: Y component Normalizedperiodograms AC / ig2 Y origin offsets

  23. Origin: Z component Normalizedperiodograms AC / ig2 Z origin offsets

  24. Annual – East codemresa gfzgrgjpl mit gtzulr

  25. Annual – North codemresa gfzgrgjpl mit gtzulr

  26. Annual – Up codemresa gfzgrgjpl mit gtzulr

  27. Relative formal errors: pole coordinates σYPO/ median(σsta) [mas/mm] σXPO / median(σsta) [mas/mm]

  28. Relative formal errors: pole rates & LOD σYPOR/ median(σsta) [mas/d/mm] σXPOR / median(σsta) [mas/d/mm] σLOD / median(σsta) [ms/d/mm]

  29. Relative formal errors: geocenter σYGC/ median(σsta) [mm/mm] σXGC / median(σsta) [mm/mm] σZGC / median(σsta) [mm/mm]

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