Navigation and service

IERS Retreat 2013

Paris, France, 23 - 24 May 2013

A Not barrier-free file. summary (PDF, 137KB) and the presentations are available.


IERS Core Role: Generation of regular, high accuracy products.

Aim of Retreat

Establish directions for IERS over next decade that will ensure this core role is meet.


University Paris-Diderot, 35 Rue Hélène Brion, Paris, France

Retreat organization

Retreat will be held over two days during which 7 topics and a summary and recommendations session will be covered. There will be 4 sessions per day with 2 session in the morning and 2 sessions in the afternoon. Each session will last 1.5 hours. The sessions will start with a 30-minute presentation that will address the issues associated with each topic. The remaining hour of the session will be discussions and the development of recommendations that will be presented at the board meeting immediately following the retreat. Two people will organize each session except the larger session 2, which has three organizers. The organizers will make the presentation and record the discussions during the sessions. Both organizers will write the final report and present the recommendations from their session. As the plan for the retreat develops in more detail, some of the lengths of the sessions may be altered to allow more discussion of the most critical topics.

The target of the workshop is to determine what can be done, determine if it is necessary and, if necessary, how do we proceed. The overall theme has to be maintaining the quality and regularity of the IERS’ products and to ensure that the service continues to meet the needs of all of its users. The path forward will be developed in detail outside of the retreat. Most likely a set of working groups will be established that will determine how to implement the recommendations of the retreat. These working groups are likely to meet over the next year.

Retreat preparation

In preparation for the retreat, session organizers are expected to develop a set of items to be discussed in their session and potential recommendations should also be considered. Input from the community should be sought in developing these items and recommendations. The ideas about the session and types of recommendations should be submitted to the directing board about one week before the EGU meeting in Vienna. An informal evening meeting is planned at the EGU meeting to review the preparations for the retreat. The day of the meeting will be decided as the EGU meeting approaches.

Session 1

Move towards "real-time" products (products that support low latency (1-sec) applications of geodetic data; eVLBI incorporation). The theme to be addressed here is the need for low latency high accuracy EOP for the real-time GNSS applications being developed. A current trend in these applications is the use of precise point positioning methods, as opposed to differential positioning, and these PPP methods need to define the terrestrial reference frame through the orbits and clocks on the GNSS satellites. Currently this is a challenging task and this session will examine how to best deploy IERS resources to achieve these aims.

Chaired by Harald Schuh and Jens Wickert

Session 2

Rigorous combined products (e.g., services are generating EOP and terrestrial RF simultaneously; IERS is simply averaging EOP values). This topic is considered critical to the future of the IERS and will occupy two sessions because of its great impact potentially on the service. Of importance here is the consideration of inclusion of both the terrestrial (ITRF) and celestial reference frames (ICRF).
The discussion here will focus on how to assess the need for rigorous combination, how best to achieve such combinations, and how to determine whether we need to proceed with such techniques. This session will be divided into two basic discussions. One will deal with the long-term product generation, the combined ICRF and ITRF product, and the other discussion will focus on the day-to-day generation of IERS products. The implementation of a rigorous combination approach also has major impact on the services contributing to the IERS and the path forward will need to establish the impact on the services as well. It will also need to be established how we blend pre-spaced geodesy measurements with the conventional astronomical ones. This session will be allotted two time slots.

Chaired by Zuheir Altamimi, Manuela Seitz and Richard Biancale

Session 3

Long-term stability and parameterization of the reference frame. This session will address how to parameterize the ITRF. With the GGOS aims of defining an ITRF accurate to 1 mm and 0.1 mm per year, serious consideration has to be given to precisely how to define such a system when there are unknown non-secular components to the motions of all of the ITRF sites. The session will outline the steps that need to be taken in understanding how to incorporate such phenomena as earthquake co-seismic and post-seismic deformations, anthropogenic and natural loading phenomena, and other deviations from secular motion. Also to be addressed is how to approach the appropriate parameterization of variations in the ICRF. Consideration of source structure variation and source evolution needs to be addressed. The impact on the services will need to be assessed.

Chaired by Xavier Collilieux and Daniela Thaller

Session 4

Next Generation of models and Center-of-Mass products. How to establish need (improvements needed in diurnal/semi-diurnal EOP, tidal loading)? This session will address the types of model updates that should be included in the IERS conventions, and how to determine the need for these updates. The inclusion of new IERS products such as a center of mass product will also be discussed. Models and new products should also consider the celestial component of the reference systems as well.

Chaired by Richard Gross and Tonie van Dam

Session 5

EOP prediction improvements. This session will address the need for EOP prediction accuracy and how best to achieve these accuracies and determine the timescales over which predictions need to be made. The uses of these prediction products will also need to be determined and their requirements established.

Chaired by Brian Luzum and Christian Bizouard

Session 6

Unification of product formats. This session will cover two broad areas. One will be the unification of the IERS product formats to allow easy comparison and combination. The other area will be establishing modern standards for product formats such as the metadata content and how to express that. The target products here are the EOP products that are used by wider IERS community.

Chaired by Thomas Herring and Laurent Soudarin.

Session 7

Establish mechanisms that allow changing contributions. The aim of this session is to provide a mechanism for evolving the IERS as time goes on and needs change. During the last retreat, over a decade ago, new components of the IERS were established. Since then these components have stayed in place and there is no formal mechanism for changing the components of the IERS. This session will look at how best to establish such procedures so that the IERS can evolve more quickly between retreats.

Chaired by Bernd Richter and Chopo Ma

Summary and Recommendations

The final session will summarize the retreat and develop a set of synthesized recommendations to be passed on to the full board at the IERS board meeting immediately following the retreat. All members of the retreat will be involved in this discussion and the chair and director of the IERS will lead it.

Download: Not barrier-free file. summary (PDF, 137KB)

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