DENSIFICATION OF THE ITRF VELOCITY FIELD

Transcription

1 DENSIFICATION OF THE ITRF VELOCITY FIELD THROUGH A COLLABORATIVE APPROACH W ORKING GROUP I NTEGRATION OF D ENSE VELOCITY F IELDS INTO THE ITRF J. L E G R A N D, C. B R U Y N I N X, E. S A R I A ( A F R E F ), J. G R I F F I T H S ( N A R E F ), M. C R AY M E R ( N A R E F ), J. D AW S O N ( A P R E F ), A. K E N Y E R E S ( E U R E F ), L. S Á N C H E Z ( S IR G A S ), A. S A N TA M A R Í A- G Ó M E Z ( U LR ), Z. A LTA M I M I I A G S C I E N T I F I C A S S E M B L Y 2013 S e s s i o n : 1. 5 R e g i o n a l R e f e r e n c e F r a m e s

2 APREF - APR ROB NAREF GSB NRCAN 606 stations 600 stations EUREF - EUR NAREF - NGS 296 stations 2832 stations AFREF - AFR SIRGAS - SIR ITRF2008 densifications 197 stations 333 stations

3 PRINCIPLE: WEEKLY COMBINATIONS IGS SIRGAS Individual weekly SINEXs Individual ACs submit: cleaned weekly SINEXs cumulative solution and time series discontinuities station site logs (if available) APREF EUREF AFREF NAREF Cumulative solution aligned to ITRF (Stacking of weekly combined SINEXs) Weekly combined SINEXs

4 PRINCIPLE: WEEKLY COMBINATIONS Individual weekly SINEXs IGS SIRGAS APREF EUREF AFREF NAREF Cumulative solution aligned to ITRF (Stacking of weekly combined SINEXs) Weekly combined SINEXs

5 WEEKLY COMBINATIONS

6 WEEKLY COMBINATIONS Data cleaning rejection of the incorrect solution inconsistent antenna modeling (igs05.atx / igs08.atx) incorrect metadata (antenna/radome type, eccentricities) (sub-network: stations in at least 2 solutions) Covariance matrix re-scaling 2-step approach: harmonization of the position formal errors prior to combination re-scaling by the estimated variance factor (sub-network: stations in at least 2 solutions) Computation of transformation parameters (sub-network: stations in at least 2 solutions) Final weekly combination matrix re-scaling transformation parameters fixed (Full network)

7 WEEKLY COMBINATION RMS AFR EUR IGS NGS GSB SIR APR igs05.atx IGS EUR NGS GSB SIR RMS Up RMS 2D igs08.atx APR AFR igs08.atx APR AFR IGS EUR NGS GSB SIR

8 PRINCIPLE: WEEKLY COMBINATIONS Individual weekly SINEXs IGS SIRGAS APREF EUREF AFREF NAREF Cumulative solution aligned to ITRF (Stacking of weekly combined SINEXs) Weekly combined SINEXs

9 CUMULATIVE SOLUTION

10 CUMULATIVE SOLUTION: DISCONTINUITIES Discontinuities coming from individual solutions majority of common stations have different discontinuities e.g. EPN vs IGS: 40% stations in full agreement, 60% with differences! reasons: different analyst, different data span, approximate date, problem of metadata or antenna modeling Harmonization for ~1200 stations in at least 2 solutions keep only required discontinuities check all available site logs (material change: date of installation) Iterative process, still in progress. Next steps: check also the dates of displacements linked to earthquakes feedback to contributors

11 CUMULATIVE SOLUTION: NETWORK Stations available in the current combination 1770 stations ~ 1000 NGS stations not yet included in the combination

12 CUMULATIVE SOLUTION: NETWORK Stations available in the current combination 1770 stations Sub-network used to mitigate the aliasing effect [Collilieux et al. 2011] igs08 core network + good stations with more than 10 years of data

13 CUMULATIVE SOLUTION: WEEKLY RMS solution # stations COMBINATION 1770 IGS 720 AFR 130 APR 396 EUR 264 GSB 553 NGS 863 SIR 255

14 CUMULATIVE SOLUTION: TIME SERIES ONSA A 10402M004 (Onsala, Sweden) IGS AFR APR EUR GSB NGS COMBINATION

15 CUMULATIVE SOLUTION: TIME SERIES LROC A 10023M001 (La Rochelle, France) IGS APR EUR NGS COMBINATION

16 CUMULATIVE SOLUTION: TIME SERIES COT1 A 49469M001 (Tucson, Arizona, USA) IGS

17 CUMULATIVE SOLUTION: TIME SERIES COT1 A 49469M001 (Tucson, Arizona, USA) IGS NGS

18 CUMULATIVE SOLUTION: TIME SERIES COT1 A 49469M001 (Tucson, Arizona, USA) IGS COMBINATION NGS

19 VELOCITY FIELD

20 HORIZONTAL VELOCITY FIELD (PRELIMINARY COMBINATION)

21 HORIZONTAL VELOCITY FIELD (ITRF2008 ONLY)

22 HORIZONTAL VELOCITY FIELD (PRELIMINARY COMBINATION)

23 VERTICAL VELOCITY FIELD (PRELIMINARY COMBINATION)

24 CONCLUSIONS

25 CONCLUSIONS/PERSPECTIVES Successful combination No degradation, improvement of individual solutions Comparison of solutions: more reliability More populated and longer time series SIRGAS/EUREF regional solutions Finish this combination (+ ~1000 stations, discontinuities) Main drawback: mix of igs05.atx and igs08.atx models Next year(s), new combination using: IGS Repro 2 new densifications (IGS Repro2 compliant)