HR: 10:35h
AN: G22A-02 INVITED     [Abstracts]
TI: Enhancing Earth Rotation Studies by Combining Earth Rotation Measurements
AU: * Gross, R S
EM: Richard.Gross@jpl.nasa.gov
AF: Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 United States
AB: The Earth rotates about its axis once a day, but does not do so uniformly. Instead, the rate of rotation fluctuates by up to a millisecond per day, and the Earth wobbles as it rotates. These changes in the Earth's orientation occur over a wide range of time scales, from subdaily to decadal and longer, reflecting the wide variety of geophysical processes that are causing the Earth's orientation to change. A number of different techniques have been and are currently being used to measure the Earth's changing orientation in space, including lunar occultation, optical astrometry, lunar and satellite laser ranging, very long baseline interferometry, and the global positioning system. These different measurement techniques have their own unique strengths and weaknesses. They may be sensitive to a different subset and/or linear combination of the Earth orientation parameters, the averaging time for their determination may be different, as may be their duration, the interval between observations, and the precision with which they can be determined. By combining Earth orientation measurements that have been determined by these different techniques, a series of the Earth's orientation can be obtained that is potentially more accurate than that determined by any single technique and that spans a time interval greater than that spanned by any single technique. The improved accuracy and longer duration of such combined Earth orientation series enhance scientific studies of the Earth's rotation, enabling greater understanding of its causes and consequences.
DE: 1239 Rotational variations
SC: Geodesy [G]
MN: 2004 AGU Fall Meeting