Polar Motion Measurements: Subdecimeter Accuracy Verified by Intercomparison

• Published in: Science (American Association for the Advancement of Science) 1985-09, Vol.229 (4719), p.1259-1261
• Main Authors: Robertson, D. S., Carter, W. E., Tapley, B. D., Schutz, B. E., Eanes, R. J.
• Format: Article
• Language: English
• Subjects: Artificial satellites; Astronomical rotation; Earth; Earth, ocean, space; Earthquakes; Exact sciences and technology; External geophysics; Geodesy; Geodesy and gravity; Geodetic research; Geophysical research; Lasers; Measurement; Meteorology; Observational research; Observations; Radio observatories; Rotation; Seismological research; Space based observatories; Space research; Systematic errors
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.229.4719.1259

An important bound on the accuracy of modern techniques for monitoring polar motion is established by intercomparison of measurement series from two different observing techniques, very long baseline interferometry and satellite laser ranging. The root-mean-square differences between the estimates of the pole position from both techniques are shown to be only 2 milliseconds of arc (about 6 centimeters at one Earth radius). In the absence of common systematic errors, these differences bound the total errors in both sets of estimates. An initial investigation did not reveal any clear signature in the pole position that seems to be associated with major earthquakes. Continued measurements at this level of accuracy hold promise for resolving long-standing arguments over such questions as the nature of the excitation mechanism required to maintain the motion of the pole.