HR: 0800h
AN: G21B-0498    [Abstracts]
TI: Contributions of the North American Reference Frame Working Group to the next realization of the Stable North American Reference Frame (SNARF)
AU: * Henton, J A
EM: jhenton@NRCan.gc.ca
AF: Natural Resources Canada, Geodetic Survey Division, 615 Booth Street, Ottawa, ON K1A 0E9, Canada
AU: Craymer, M R
EM: craymer@NRCan.gc.ca
AF: Natural Resources Canada, Geodetic Survey Division, 615 Booth Street, Ottawa, ON K1A 0E9, Canada
AU: Lapelle, E
EM: elapelle@NRCan.gc.ca
AF: Natural Resources Canada, Geodetic Survey Division, 615 Booth Street, Ottawa, ON K1A 0E9, Canada
AU: Piraszewski, M
EM: mpirasze@NRCan.gc.ca
AF: Natural Resources Canada, Geodetic Survey Division, 615 Booth Street, Ottawa, ON K1A 0E9, Canada
AB: Since the beginning of 2001, the Geodetic Survey Division of Natural Resources Canada (NRCan) has been playing a leading role in the North American Reference Frame (NAREF) Working Group of IAG Sub-commission 1.3c (Regional Reference Frames for North America). This supports the International Earth Rotation and Reference Frames Service (IERS) and the International GNSS Service (IGS) initiatives to densify the International Terrestrial Reference Frame (ITRF) in North America. The objective is to provide a globally consistent reference frame, including velocity models, procedures and transformations, tied to ITRF in which scientific and geomatics results (e.g., positions in tectonically active areas) can be produced and inter-compared. The NAREF densification network has evolved from a hundred continuously-operating GPS reference stations to nearly 1000. Following internationally accepted densification methodologies, regional North American GPS solutions, from several groups in Canada and the U.S., are combined into a single NAREF weekly solution that is aligned with the ITRF reference frame. The weekly NAREF solutions are subsequently combined into a single cumulative solution to provide estimates of both station coordinates and their velocities with respect to a consistent reference frame throughout North America. In order to provide an increased spatial sampling of crustal deformation throughout Canada, we also estimate velocities at sites of the Canadian Base Network (CBN) by combining over ten years of repeated multiple-epoch (episodic) GPS measurements. Initiated in 1994, the CBN is a network of high-stability pillar monuments with forced-centering mounts for GPS receiver antennas. To determine individual station velocities, regional CBN solutions for each measurement epoch are systematically combined into a Canada-wide cumulative solution. The resulting NAREF and CBN velocity fields display a high level of spatial- coherence and are being used to evaluate crustal deformations in various parts of the continent and to more accurately determine the motion of stable North America. More specifically these products have been used in the definition of a plate-fixed Stable North American Reference Frame (SNARF) for the Plate Boundary Observatory component of the EarthScope project. In this paper we present the NRCan-determined GPS velocity fields, and the resulting North American rotation pole derived from these efforts. We also describe recent changes in our processing and combination strategies in response to new procedures adopted by the IGS.
DE: 1209 Tectonic deformation (6924)
DE: 1229 Reference systems
DE: 1243 Space geodetic surveys
DE: 8107 Continental neotectonics (8002)
DE: 8158 Plate motions: present and recent (3040)
SC: Geodesy [G]
MN: 2007 Fall Meeting