HR: 10:20h
AN: G32A-01 INVITED     [Abstracts]
TI: Making Sense of Evolving Reference Frames for North America
AU: Craymer, M
EM: craymer@nrcan.gc.ca
AF: Geodetic Survey Division NRCAN, 615 Booth Street, Ottawa, ON K1A 0E9, Canada
AU: * Sella, G
EM: giovanni.sella@noaa.gov
AF: NOAA-National Geodetic Survey, 1315 East-West Hwy, Silver Spring, MD 20910, United States
AB: The World Geodetic System 1984 (WGS84) and North American Datum of 1983 (NAD83) are the most widely- used spatial reference systems in North America. NAD83 is the national reference system used for georeferencing by most federal and provincial/state agencies while WGS84 is the default "native" system used by the Global Positioning System (GPS) and commercial GPS receivers. The physical realization of these reference systems have undergone several updates since they were first introduced over two decades ago. NAD83 has evolved from a traditional, ground-based horizontal control network to a space-based 3D realization fully supporting modern GPS techniques and the integration of both horizontal and vertical reference systems. WGS84, on the other hand, has no publicly accessible ground-based network. It is accessible only via broadcast orbits that provide positions with an accuracy of about a meter at best (with augmented corrections). More recently, a new reference systems called the Stable North American Reference Frame (SNARF) has been created primarily in support of Plate Boundary Observatory component of the EarthScope project. We explain the differences between these global and regional reference frames and as well as their relationship to each other. We also discuss some problems that occur when these relationships are not properly represented as done, for example, with NAD83 in the vast majority of GPS receivers.
DE: 1211 Non-tectonic deformation
DE: 1229 Reference systems
DE: 1241 Satellite geodesy: technical issues (6994, 7969)
DE: 1243 Space geodetic surveys
DE: 1244 Standards and absolute measurements
SC: Geodesy [G]
MN: 2007 Joint Assembly