****************************************************************************** dorismail 26-Nov-2007 13:54:01 Message No 0523 ****************************************************************************** Author: Zuheir Altamimi Subject: ITRF session at EGU2008 Author: Zuheir Altamimi & Jim Ray EGU General Assembly -- Vienna, Austria, 13-18 April 2008 http://meetings.copernicus.org/egu2008/ Dear Colleagues, The General Assembly of the European Geosciences Union will be held in Vienna, Austria, 13-18 April 2008. We draw your attention in particular to session "G4 - The impact of technique errors on reference frame accuracy and stability": Experiences with the 2005 version of the International Terrestrial Reference Frame (ITRF2005) have underscored once again significant differences among the contributing observing techniques and their importance in limiting the accuracy and stability of the combined frame. Those differences related to variations in intrinsic sensitivity to certain parameters (such as the Earth's geocenter) enable the ITRF to have the potential of improved accuracy over any single technique. However, other differences, such as related to choices in analysis models, can degrade the global combination. Systematic errors in techniques, both of known and unknown causes, also degrade the ITRF accuracy and can lead to long-term instabilities and other weaknesses. Given the current high precisions achieved by all the space geodetic observing methods, it is vital to improve our understanding of the specific errors of each and their effects on ITRF. All potential error types must be considered including differences in data modeling. It is equally important to develop techniques to mitigate error effects whenever possible. As always, it continues to be critically important to understand the physical relationships between the reference points of co-located systems at a highly detailed and accurate level, the so-called "site tie problem". While much has been said about this topic, the progress for ITRF realizations has been disappointing and this continues to be a limiting error in the overall combination. Contributed papers in all aspects of these inter-connected problems are requested. Work that illuminates characteristics of individual techniques or their combinations is sought. Approaches that either attenuate technique-specific errors or help understand their causes are especially needed. Important Dates: 14 January 2008: Deadline for receipt of abstracts at http://www.cosis.net/members/meetings/programme/view.php?m_id=49&p_id=325 31 March 2008: Deadline for pre-registration & hotel booking Please consider submitting a paper for this symposium or contact us directly if you have any questions. Sincerely, Zuheir Altamimi, altamimi@ensg.ign.fr ENSG/LAREG, Institut Geographique National Jim Ray, jimr@ngs.noaa.gov Geosciences Research Division, National Geodetic Survey -- ---------------------------------------------------------------------- Zuheir Altamimi Email : altamimi@ensg.ign.fr Institut Geographique National Phone : 33 1 64 15 32 55 ENSG/LAREG FAX : 33 1 64 15 32 53 6-8 Avenue Blaise Pascal 77455 Champs-sur-Marne, FRANCE ---------------------------------------------------------------------- Please do not reply directly to this message, but send comments and suggestions to IDS.central.bureau@cls.fr