From craymer at nrcan.gc.ca Tue Feb 27 13:28:29 2007 From: craymer at nrcan.gc.ca (Mike Craymer) Date: Tue, 27 Feb 2007 16:28:29 -0500 Subject: [IGSMAIL-5563]: 2007 Joint Assembly - Definition, densification & the inter-relation of reference frames for the Americas Message-ID: ****************************************************************************** IGS Electronic Mail 27 Feb 13:28:32 PST 2007 Message Number 5563 ****************************************************************************** Author: Mike Craymer Dear Colleagues, Abstracts are due 1 March 2007 2359 UT for the 2007 Joint Assembly of AGU and a number of other Earth Science organizations to be held on 22-25 May 2007 in Acapulco, Mexico. In particular, we invite contributions to the following special session. G11: Definition, densification and the inter-relation of reference frames for the Americas: ITRF, NAD83, SIRGAS and SNARF One of the main tasks of modern geodesy is to define and maintain terrestrial reference frames for measuring and mapping the Earth surface and its deformations. How well the reference frame can be realized has important implications for our ability to study both regional and global properties of the Earth, including post-glacial rebound, sea level change, plate tectonics, regional subsidence and loading, plate boundary deformation, and Earth orientation. A terrestrial reference frame is realized mainly through international and national conventions. Modern reference frames are defined through the use of space geodetic techniques such as VLBI, SLR, GPS and DORIS. None of these techniques is sensitive to all degrees of freedom of a reference frame (translation, rotation and scale). Information from each technique is needed to define a frame in its entirety. The wide use of GPS has also resulted in a number of efforts to densify the International Terrestrial Reference Frame (ITRF) in various regions, (e.g., the NAREF effort in North America and SIRGAS in South America), In addition, attempts have been made to establish more modern regional reference frames such as the Stable North American Reference Frame (SNARF). All of these frames must not only be "tied" to one another and to older, established reference frames, e.g., the North American Datum of 1983 (NAD83), but also must maintain temporal and spatial continuity. This session seeks contributions from across the Americas on efforts to define, densify, inter-relate and utilize local, regional and international reference frames, and to discuss the impact such frames have on geodetic results, including national reference frames and the monitoring of sea level change, crustal deformation, glacial isostatic adjustment, etc. To submit an abstract go to For more information about the meeting go to Conveners: Giovanni Sella National Geodetic Survey Silver Spring, MD, USA Mike Craymer Geodetic Survey Division, Natural Resources Canada Ottawa, Canada