IERS Message No. 25: Summary of the IERS Combination Research Mee ting

central_bureau at central_bureau at
Wed May 22 13:20:04 UTC 2002

IERS Message No. 25                                            May 22, 2002

Summary of the IERS Combination Research Meeting, April 25, 2002

Dear colleagues,

Please find hereafter a short summary of the IERS Combination Research
Meeting, held on April 25, 2002 during the EGS General Assembly in Nice,

With best regards,
Daniela Thaller

Daniela Thaller
Forschungseinrichtung Satellitengeodaesie
Technische Universitaet Muenchen
Arcisstrasse 21
D-80290 Muenchen / Germany
Phone : ++49-89-289-23186
Fax   : ++49-89-289-23178
E-mail: daniela.thaller at

IERS Combination Research Meeting

April 25, 2002

EGS XXVII General Assembly 2002

Acropolis Conference Centre, Nice, France

1. General Introduction

- short overview over the agenda for the meeting given by M. Rothacher
- web sites:
- two different mailing lists for CRC purposes:
  crc_forum at (open for all people interested in CRC activities;
     most part of the mails)
  crc at (only for internal purposes)

2. IERS Products

present status and future perspective of the IERS products given by M.
- preliminary overview of present IERS products is finished, but
  feedback and supplementation from some of the IERS product centres is
  still missing.
- completed overview will soon be accessible via the IERS web pages.

3. IERS ERP Alignment Campaign

The IERS Analysis Campaign to align EOPs to ITRF2000 / ICRF is already
started. M. Rothacher gave a short overview:
- aim: more consistent products
- two steps:
  1. Generation of EOP series (deadline for the submission was
     March 15, 2002)
  2. Analysis of EOP series (final results should be presented at the
     IERS Workshop in November 2002)
- status of the campaign: 10 VLBI series, 16 GPS series, 6 SLR series
  and 1 DORIS series

First results of an analysis of the contributing EOP series, done by R.
Dill (FESG / Technical University Munich), presented by M. Rothacher.

- long term goal: use SINEX format for exchange of solutions
  (incl. variance-covariance information).
- many ERP format problems / inconsistencies; common ERP format should
  be used.
- IVS pilot project EOP series (1999-2000) not yet included (comment:
  now, these series are included as well).
- this analysis should not be mixed with routine processing for the
  official IERS products; ERP Alignment Campaign is only for research
- until now no other groups have analyzed the available EOP series
  (reason: contributing data available only since March 2002), but more
  analysis is necessary.
- results from the different analysis groups are expected at the IERS
  Workshop in November 2002.

4. SINEX Combination Campaign

A second campaign for the implementation of new combination strategies
will be started.
- combination of "weekly" solutions of different techniques with station
  coordinates + EOP + (ICRF)
- development of standards for common modeling and parameterization
- combined "weekly" solutions as the basis for final routine EOP
- combined multi-year solution (ITRF + ICRF) as basis to produce fully
  consistent EOP series

The actual status and future plan was given by M. Rothacher:
- SINEX datapool is already created (accessible via web sites of IERS
  Analysis Coordinator) with
  - weekly GPS solutions from IGS Analysis Centres
  - 28-days solutions of the ILRS pilot project 'positioning and earth
    orientation' 1999
  - VLBI solutions from IAA for 1999
- time-table for contributions and combinations:
  - May 15, 2002: call for participation
  - June 15, 2002: deadline for submission of proposals
  - August 15, 2002: deadline for submission of series
  - November 2002, IERS Workshop: first results
  - April 2003, EGS: results

- as input: not only one (already combined) solution per technique, but
  more individual solutions (because of research purposes).
- older VLBI SINEX files are now available again from T. Herring; these
  will be included as input files as well (comment: the files of the year
  1999 are now included).

5. SINEX format

The proposed new format description is available on the web sites of the
IERS Analysis Coordinator.
M. Rothacher gave a short overview over the changes concerning SINEX 2.0
and presented the statements from IGS, IVS and ILRS.
The final version of SINEX 2.0 will be available on May 15, 2002.

- more explanatory text for the description of the blocks, parameters,
  formulas is required.
- STATISTICS block 'strongly recommended' if information is available.
- constraints problematical: tight constraints should be forbidden.
- normal equations: tests will be performed if the constraints for every
  solution can be taken away and if the 'free' solution can be recovered.
  Normal equation blocks will be included in the format.
- naming of a station after an earthquake not clear: use a new solution
  number, but do not change the DOMES number;
  difference to 'point ID': 4-character abbreviation + point ID
  corresponds exactly to a unique DOMES number
- problems of distinguishing between GPS, GLONASS, (Galileo): at the
  moment the same code is used for these techniques, i.e. 'P'
- parameters for solar radiation pressure will be kept.

6. CRC activities

Short presentations from:
- J. Vondrak: Astronomical Institute, Academy of Sciences of the
  Czech Republic
- D. Angermann: DGFI
- M. Rothacher: FESG, Technical University Munich
- R. Gross: JPL
Presentations during session G9.05 on Friday, April 26:
- J. Vondrak: Astronomical Institute, Academy of Sciences of the
  Czech Republic
- D. Angermann: DGFI
- P.-H. Andersen: FFI
- P. Yaya: GRGS
- P. Sillard: IGN
No presentations:
- GFZ Potsdam

7. Combination strategies

No discussion at this meeting.

8. IERS Combination Workshop

4 days in early November 2002 in Munich
- participants: all IERS components and contributing services.
- topics: EOP; ITRS/ITRF; ICRS/ICRF; Contributions from Global
  Geophysical Fluids Centres (GGFC); Conventions/Standards; Rigorous
  combination of ITRF + EOP + ICRF; IAU Resolutions.
- preparation with position papers for each session (available before
  the workshop).
- coordination with IERS Directing Board to retain official character.

9. Varia

No further topics and comments.

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