[IGSMAIL-3604]: IERS Analysis Coordination

Tue Nov 20 12:00:27 PST 2001

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IGS Electronic Mail      20 Nov 11:59:51 PST 2001      Message Number 3604
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Author: Markus Rothacher

Dear Colleagues,

at the IERS Directing Board Meeting in Brussels in October I took over
the
responsibilities of the IERS Analysis Coordinator. This was made
possible
by the fact that two positions are now available at my institute for the
tasks
of the Analysis Coordinator and for the Combination Research Center
activities.

The two persons who are now working with me in this field are:

  Robert Dill             (dill at bv.tum.de)
  Daniela Thaller         (daniela.thaller at bv.tum.de)

Robert Dill will mainly support the IERS AC work, whereas Daniela
Thaller
will mainly be working on CRC issues.

The following actions have already been initialized or are planned for
the
next few months:

A. Coordination of the CRC Activities
   ----------------------------------

(1) Mail Exploder and Web-Pages
    ----------------------------

An e-mail exploder has been set up by the IERS Central Bureau for the
exchange of information between the CRCs and other interested groups and
may be
used by any person interested to share results, problems, ideas in the
field
of combination research within the IERS. The address is

                    crc_forum at iers.org

If you wish to receive the e-mails distributed by this exploder, please
send
an e-mail to Alexander Lothhammer at the IERS Central Bureau

                   lothhammer at iers.org

If you wish to distribute an e-mail of yours to this list, just send it
to
crc_forum at iers.org.

A web page has been established for the IERS Analysis Coordinator
activities
at
                   http://alpha.fesg.tu-muenchen.de/iers/

This web page will be maintained to reflect the goals and projects of
the
IERS Analysis Coordinator and the CRC activities.

(2) SINEX-Format
    ------------

Starting with the IGS SINEX format description (Version 1.00) Daniela
Thaller has put together a new version (Version 2.0) of the
SINEX format including all the additions and
modifications of the IVS and ILRS groups. The SINEX document together
with a
list of questions concerning the new version will be distributed to the
Technique
Coordinators of the IGS, IVS and ILRS for feedback and comments in the
next few
days. Interested groups may have a look at the format description
available on
the new web page mentioned above.
With this step we hope to ensure that only one consistent format is
followed by
all the space techniques.
As soon as the format definitions are finalized we will write a SINEX
checker
program that will be available for all groups to check their SINEX files
in order
to meet the format definition.
We also intend to put together some guidelines on how SINEX files should
be
generated to make sure that a combination is possible without problems.
Issues are e.g. how to handle constraints on the ERPs (UT1 for satellite
techniques, continuity between ERPs of subsequent days, velocity
constraints
between collocated sites for ITRF submissions, etc.).

(3) SINEX Data Pool
    ----------------

In order to test and develop their combination software packages the
CRCs
need to have access to a broad variety of SINEX files from different
techniques. We therefore plan to establish a pool of SINEX files or
links
to SINEX file archives for the CRC activities. This pool will contain

- all the contributions of the individual analysis centers to the
ITRF2000 solution
  together with all the local tie information
- SINEX files of the IGS and its combination centers
- SINEX files from the ILRS and IVS pilot project to the extent
available

These SINEX files are thought to allow first tests and to modify the
combination
software packages to deal with the SINEX files produced by different
techniques.

(4) "Weekly" SINEX Campaign
   ------------------------

It is also planned to come up with a time interval (according to the
Technique
Analysis Coordinators) for which the different techniques will deliver
SINEX
files for combination research, containing site coordinates and ERPs.
The time
interval covered by one SINEX file of the various techniques should be
compatible (e.g. 1 week for GPS, 1 24-h session for VLBI and
1 or 2 weeks for SLR).
These SINEX files will allow to

- study the consistent combination of coordinates and ERP stemming
  from different techniques
- detect and analyze systematic biases between the results of the
different
  techniques
- produce and compare time series of the different techniques
- develop algorithms to allow the production of combined multi-year
solutions
  with consistent site coordinates, site velocities and ERPs.
- study weighting strategies and datum definition strategies

These developments will be important steps in the direction of a
rigorous combination
of ITRF, ICRF and ERPs in the future.

B. IERS Campaign to align EOPs to ICRF/ITRF2000
   --------------------------------------------

This campaign was proposed by Jim Ray with the following objectives:

- generate EOP series with the highest possible consistency with ICRF
and ITRF2000
- achieve overall accuracy of 0.1 mas
- understand the origin of systematic errors between EOP series of
different ACs

This campaign is thought to improve the consistency of the IERS products
even
before a rigorous combination of ITR/ICRF/EOPs becomes possible.

The details of the campaign and the implementation plan are described on
the
new web pages of the IERS Analysis Coordinator.

C. IERS Product Quality
   --------------------

The IERS AC will start to look into the quality of the present IERS
products.
This task will consist of:

- putting together a complete list of the IERS products and their
  methods of generation, their availability, accuracy, etc.
- assessing the status of the global network of fundamental stations
- compile a list of the processing standards used by the analysis
centers
  and the consistency with the IERS conventions
- check the level of documentation of the IERS products and the
guidelines
  about the use of the products

Besides these topics the IERS AC plans a routine quality check of the
IERS products.

More details may be found on the web pages.

We are looking forward to any feedback concerning the activities
proposed here, the web pages, etc.

With best regards,

Markus Rothacher, Robert Dill, and Daniela Thaller
The IERS Analysis Coordination Team

-- 
--------------------------------------------------------------------------------
Prof. Dr. Markus Rothacher                   Phone : ++49-89-289-23191
Forschungseinrichtung Satellitengeodaesie    Fax   : ++49-89-289-23178
Technische Universitaet Muenchen             E-mail:
markus.rothacher at bv.tum.de
Arcisstrasse 21
D-80290 Muenchen / Germany