1 / 15

Current status of ITRF Co-location Sites

Current status of ITRF Co-location Sites. Zuheir Altamimi IGN-France ITRF Product Center. Co-locations. Co-location sites are vital for multi-technique combination (ITRF) Number & Distribution of co-location sites Quality of local ties

saad
Télécharger la présentation

Current status of ITRF Co-location Sites

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Current status of ITRF Co-location Sites Zuheir Altamimi IGN-France ITRF Product Center

  2. Co-locations • Co-location sites are vital for multi-technique combination (ITRF) • Number & Distribution of co-location sites • Quality of local ties • They impact the combined frame parameters (Origin, Scale, Orientation)

  3. Current Co-locations (1999 on) (8) (59) (16) (2)

  4. (2) Missing Ties SLR/GPS DORIS/GPS (1) SAKAL Brewster Ottawa Krimea URUM MIZU KUNM Haleakala VLBI/SLR (1) VLBI/GPS (4)

  5. Missing Ties • There are missing ties for point(s) in sites having multiple points from one technique • Ties after EQ are not available, e.g. • Arequipa (SLR, GPS, DORIS) • Fairbanks (VLBI, GPS, DORIS) • Ties after EQ should be used with care, esp. in case of co-seismic effect !

  6. Dubious/Discrepant Ties Disagreement btw Terrestrial & Space Geodesy vectors • Hard to discriminate between the two • ~ 15 - 20 % of the total currently available ties are discrepant  1 cm (preliminary ITRF2004 analysis)

  7. Co-locationsA new difficulty • Most of IGS/GPS stations experience jumps (discontinuities) in the time series of station positions • Most of IGS/ILRS Co-location sites are concerned • A few SLR station discontinuities are detectable • Having only one tie: to which segment should the tie be applied ??? • Careful combination analysis is needed

  8. A Co-location site with Discontinuities X GPS SLR Tie Time

  9. Current VLBI-SLR Co-locations (1999 on) (9) Inhomogeneous distribution of VLBI&SLR Networks and their Co-locations ITRF Scale in danger !!!

  10. Current VLBI-GPS Co-locations (1999 on) (36)

  11. Current VLBI-DORIS Co-locations (1999 on) (9) Poor number and distribution of VLBI and DORIS Co-locations

  12. Current SLR-GPS Co-locations (1999 on) (25)

  13. Current SLR-DORIS Co-locations (1999 on) (7) Only 7 SLR-DORIS Co-locations

  14. Current DORIS-GPS Co-locations (1999 on) (37)

  15. Conclusions • Poor number&Distr. of SLR & VLBI Co-locations • Networks configuration needs improvemnt • GGOS WG on Networks, Communications & Infrastructure • To improve tie quality, ideally repeated surveys are needed (yearly, each 2 years) • Current Ties are available at: http://itrf.ensg.ign.fr/ITRF_solutions/2004/doc/ITRF2004-localties.tab

More Related