(First iteration Feb. 2009)

(Last iteration Nov. 2009)
The IDS-3 SINEX time series may be downloaded at ftp://ftp.ids-doris.org/pub/ids/combinations/ITRF2008-IDS/IDS-3/

ITRF2008 Call

IDS Analysis

Two IDS Analysis Working Group meetings have been organized in March and June 2008 in Paris, Bureau des Longitudes, and an IDS workshop in Nice, 12-14 November 2008. Eight DORIS analysis centers participated including four official analysis centers (IGN; LCA ; GOP ; ESA), and four candidate analysis centers (NCL - University of Newcastle; GAU - Geoscience Australia; INA - Institute of Astronomy, Russian Academy of Sciences, and GSC - NASA Goddard Space Flight Center). All these centers are working to provide SINEX solutions for inclusion in the IDS combined solution that will be submitted to the IERS for ITRF2008.

This is an important step for IDS Analysis centers! Indeed for ITRF2005, only two individual DORIS solutions were included: IGN and LCA. A main goal was to improve the models and processing strategies of the new ACs, to discuss the standards and to get ready for the IDS contribution to ITRF2008.

The IDS Analysis Centers are listed hereafter. Analysis activities are coordinated by F. Lemoine.

Analysis Center Acron. Contact
Geodetic Observatory of Pecny, Czech Republic gop Petr Stepanek
Institute of Astronomy, Russian Academy of Sciences (INASAN), Russia ina Sergey Kuzin
Surya Tatevian
CNES/CLS, France lca Laurent Soudarin
Hugues Capdeville
Jean-Michel Lemoine
IGN/IPGP, France ign Pascal Willis
Marie-Line Gobinddass
ESA/ESOC, Germany esa Michiel Otten
Geoscience Australia, Australia
(with support of GSFC)
gau Ramesh Govind
Frank Lemoine
GSFC, USA gsc Frank Lemoine
University of Newcastle, UK ncl Philip Moore

The IDS combinations of weekly solutions for the station coordinates and the Earth Orientation Parameters are realized with CATREF, the IGN/LAREG Software.

Coordination Center Acron. Contact
CLS/CNES ids (TBC) JJacques Valette
Philippe Yaya
Pascale Ferrage
LAREG/IGN (software and strategy support) - Zuheir Altamimi


Weekly SINEX series contributions

The following table summarizes the AC submissions and associated main models as well as the DORIS SINEX series provided for the contribution to ITRF2008.
See also the DORIS satellites constellation history status.

AC Software Sol. Id. Type (1) Data span Satellites (2) Earth Gravity
Constraint EOPs Desc.
gop BERNESE 5.0 wd31 var-cov 1999.0-2006.9 Spot 2/4/5
Topex Envisat
Jason-1 in 2002
EIGEN-GL04S annual, 100X100 loose motion, rate dsc
ina GYPSY/OASIS 4.03 wd03 var-cov 1997.0-2008.8 Spot 2/5
Spot 4 (except 05/98-01/99)
Topex Envisat
fixed, 120x120
loose motion
rate (constrained)
lca GINS/DYNAMO wd20 var-cov 1993.0-1998.4
Spot 2/3/4/5
Topex & Envisat
(Topex/Envisat orbits with SLR)
drift, annual
loose motion dsc
ign GYPSY/OASIS 5.0 wd08 var-cov 1993.0-2008.8 Spot 2/3/4/5
Topex Envisat
fixed, 120x120
loose motion
rate (constrained)
gau GEODYN wd06 var-cov 2003.0-2008.8 Spot 2/4/5
annual, 160x160
loose motion
esa NAPEOS wd01 NEQ 1998.0-2008.0 Spot 2/4/5
(Envisat orbits with SLR)
EIGEN-GL05C loose motion, rate

(1) var-cov: variance-covariance, NEQ: Normal Equation
(2) Specific recommendation for Jason-1 is to exclude Jason-1 data after 2003 because of the USO sensitivity to SAA (cf AWG-June 2008)


Compliancy with IERS Call

The delivered SINEX are not yet fully compliant with the IERS call for participation requirements. The non compliant items are the followings:

  • 3 ACs (ina, ign, gau/gsc) provide UT1 in the set of EOPs for each day while the call only expects VLBI to provides UT1,
  • lca AC applies atmospheric correction while it is requested NOT to correct for any geophysical fluid loading effects, except for tidal ocean loading.

Concerning the last issue, LCA will provide a new SINEX series for which the weekly mean value of the atmospheric loading correction is removed.


SINEX preprocessing

The preprocessing of the SINEX solutions is realized per AC series and includes the following steps:

  • verification of DORIS station identification (dome #, mnemo)
  • rejection of stations over the whole time period (never used),
  • rejection of stations over specific periods (partially used),
  • verification of solution number and discontinuities (breaks - to be consolidated before weekly combination by analysis of all AC stations times series -),
  • when NEQ provided, inversion of free singular equations,
  • projection using minimal constraints and rejection of perturbating stations,
  • weekly comparison with ITRF2005 at epoch of each solution,
  • analysis and rejection of high residual stations.
  gop ina lca ign esa gau gsc ncl
vs ITRF2005 t7p-I05 t7p-I05 t7p-I05 t7p-I05 t7p-I05 t7p-I05 t7p-I05  
Internal Coherency T7p-IC T7p-IC T7p-IC T7p-IC T7p-IC T7p-IC    
Report sum sum sum sum sum sum sum sum

(to be completed)


Per week Combination

The weekly combination results from a 7-parameter transformation calculated every week using an IDS ITRF2005 datum . This datum results from a selection of DORIS stations having the best on position (< 1 cm) and velocity (< 2 mm/yr), and included in the week solution to be processed. For each week, the steps are as follows:

  • datum generation with selection of common stations to all ACs SINEX and propagation at epoch of the solutions,
  • first CATREF combination,
  • residual analysis and station rejection (minimum number needed),
  • weighting with variance factor,
  • iteration process and final combined solution with TRF parameters.

Note that at least 3 solutions are needed to generate a weekly combined solution. That is to say that a combination is possible over the 1997.0-2008.8 period.

Combination results (under construction)