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Workshops
IERS Retreat 2003
Observatoire de Paris, Paris, France,
March 31 - April 1, 2003
The most recent "retreats" were taking place in 1996 (IERS TN 22) and 1998
(Potsdam).
The reasons for the IERS Retreat 2003 (Paris) are manifold:
- the dramatic increase in accuracy of space geodetic results in the last few
years:
- Site coordinates at 10-9,
- Earth Orientation Parameters at 10-9,
- Gravity field soon at a similar level,
- the Technique Services have been well established:
- Better coordination of technique products,
- Much better situation to go for consistent and rigorously combined products,
- many new missions and projects posing new challenges:
- Gravity missions (CHAMP, GRACE, GOCE, ...),
- Altimetry missions (JASON-1, ENVISAT, ICESAT, ...),
- Astrometry missions,
- IGGOS
- and first impression on the new IERS structure (about 2 years old).
The IERS Retreat 2003 was organised by the IERS CB and took place at the
Observatoire de Paris from March 31 to April 1, 2003, followed by an IERS
Directing Board meeting on April 2, 2003. Representatives from all IERS
components and the Technique Services were invited as well as external
experts from various fields of interest (altimetry, astronomy, global
gravity field, new satellite missions, rigorous combination and
consistency considerations, IGGOS). The participants are listed in
Annex I.
Following the programme (see Annex II) the retreat started with an overview of
the present situation presented by the various components:
- IERS internal components: PCs, GGFC, CRC, CB answering the questions:
- What is the status of original proposal and the products?
- What changes are envisaged for the present products?
- What products are planned for the future?
- Techniques Services: IGS, IVS, ILRS, IDS and
- External input about important developments in astronomy, IGGOS, altimetry,
new missions, gravity field, combination and consistency of IERS products
gave statements concerning the questions:
- How does the IERS contribute to this project / service?
- What does the project / service expect to get from the IERS?
- How can the project / service contribute to the IERS?
To prepare the discussion all presenters were asked to send in a "half page"
contribution stating the principle ideas. In Annex III the "half page"
statements are summarized for the IERS components (Product Centres (PC),
Central Bureau (CB), Global Geophysical Fluid Centres (GGFC), ITRF
Combination Centres (ITRF CC), Combination Research Centres (CRC)), the
Technique Centres (IGS, ILRS, IVS, IDS) and the external experts.
The IERS vision and goals were worked out in groups to put together a list of
future requirements and future products. The groups representing the fields
"astronomy", "gravity and geophysical fluids", "technique centres"
(including altimetry), "combination" and "IGGOS" had to find answers to the
following questions:
- What are the future requirements?
- What does the IERS offer already?
- What are the deficiencies of the present IERS to fulfil these requirements?
- What are the future IERS products and how do they look like?
The outcome of the group discussions to the listed five topics is given in
Annex IV.
Finally the organizational and structural consequences were discussed with the
focus on:
- What are the organizational / structure consequences?
- Working groups, Pilot projects, Call for Participation?
- Action items and persons in charge?
Decisions:
- New naming of IERS:
The IERS was renamed in:
International Earth rotation and Reference systems
Service (IERS)
(Service international de la rotation de la Terre et des systèmes de
référence)
The new name better reflects the fact that the activities of the IERS do not
only consist in producing Earth orientation parameters but also in
defining and maintaining the celestial and terrestrial reference systems
and frames. IAU, IUGG/IAG and FAGS have been informed.
- Statements concerning IGGOS:
- IERS, as a joint service of IAU and IUGG, sees its role as contributing to
the astronomical as well as to the geodetic and geophysical
communities.
- IERS agrees with and supports the proposed vision and the overall goals of
IGGOS.
- IERS will contribute to IGGOS, as a service, with its multi-technique
products including terrestrial and celestial reference frames as well as
Earth orientation parameters, Conventions, Global Geophysical Fluids
Centre activities and its data base / information system. IERS will also
contribute its expertise in combination and co-location of techniques.
- IERS is interested in a close cooperation with the International Centre
for Global Gravity Field Models as a component of the International Gravity
Field Service to ensure the consistency of the products.?
- To accomplish its goals IERS depends on the contributions of the IGS,
ILRS, IVS and the planned IDS. This is formally recognized through the
structure of the IERS and of these services.
- The IERS looks forward to working with IGGOS as it proceeds to implement
its vision and goals.
- Gravity field community:
To have a better link to the gravity community,.that is also using the IERS
products, a representative of IGFS (especially IGCC) will be invited to the
IERS DB meetings as permanent guest. A close relationship is important to
ensure the consistency between IERS and gravity field products (including the
IERS Conventions).
- Altimetry:
The IERS DB would also be interested in a closer connection to the altimetry
community.
- Global Geophyiscal Fluid Centres:
There was a clear statement of the IERS DB that the GGFC are an essential
part of the IERS structure due to the significant interaction between the GGFC
and the other IERS components. The GGFC products are of importance for the
understanding of temporal and spatial variations of EOP and station positions
as well as for numerous applications in geosciences.
- Combination Pilot Project:
It was decided that the IERS SINEX Combination Campaign should evolve into a
pilot phase of routine product generation, the "IERS Combination Pilot
Project". The aim of the combination pilot project is the rigorous combination
of station coordinates, EOP series, and quasar coordinates from weekly SINEX
files of all major space geodetic techniques including time series of all
three components: station- and quasar coordinates as well as EOP.
The Call for Participation (CfP) will allow for the following type of
contributions:
- Technique Centres (or groups combining at the observation level): They
contribute routinely with "weekly" (=session for VLBI, =week for GPS, SLR,
DORIS) technique-specific SINEX files,
- Combination Centres: They routinely combine "weekly" SINEX files from
all major space geodetic techniques containing station coordinates, EOP
and quasar coordinates into combined consistent weekly IERS products
(series of weekly station (and quasar coordinates) and daily EOPs),
- Associated Combination Centres: They routinely produce at least one
special combined product for the IERS. Examples: combined subdaily EOP
series, combined nutation offset series, combined troposphere or
ionosphere products etc.
The Combination Pilot Project will be organized and coordinated by the
Working Group on Combination (see below).
Establishment of WGs
- WG on Combination
The Combination Pilot Project will be run by the WG on Combination:
The WG will be set up according to the ToR.
Initial members are:
IERS AC, 1 representative of each PC, 1 representative for all CRC, 1
representative of each TC, 1 representative of each ITRF CC, IERS CB and
representatives of the groups answering the CfP for the "Combination Pilot
Project" and being accepted by the proposal evaluation.
The charter of the WG will be drafted till the beginning of May and
discussed within the initial members of the WG. The WG will prepare the
CfP for the "Combination Pilot Project" and release it by the end of June
/ beginning of July 2003. All responses received till Sept. 15, 2003 will
be evaluated by the WG and a proposal will be sent to the IERS DB for
approval. The pilot project will start on January 1, 2004.
Apart from the coordination of the Combination Pilot Project the WG will
work on:
- Document with guidelines / definitions for a rigorous combination,
- Input definitions and standards for combination,
- Product specification (routine combined products and long time series of
past data),
- Handling of and guidelines for site problems,
- Validation issues.
- WG on ITRF datum
It is planned to reconstitute the WG on ITRF datum within the IERS frame
work according to the ToR.
- WG on Site Co-location
A WG on Site Co-location will be set up within the IERS in accordance with
the CSTG. As chair of the WG John Long is foreseen, who already headed the
CSTG subcommission on ISGN. The charter and the initial member list of the WG
will be discussed within the IERS DB.
Planned workshops
- Workshop on Site Co-location
A first workshop dealing with the main topics of the WG: site surveying,
adjustment of local networks, SINEX generation with full variance-covariance
information and other co-location issues (e.g. environmental parameters)
will be held in Matera / Italy in October 2003.
- Workshop on Combination
To discuss the first experiences of the Combination Pilot Project a workshop
is planned in the fall of 2004.
Prague, Munich, Frankfurt, April 23, 2003
Jan Vondrak, Chair IERS Directing Board
Markus Rothacher, Analysis Coordinator
Bernd Richter, Central Bureau
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