Polar motion and Earth rotation

Tapley, Byron D

doi:10.1029/rg021i003p00569

Cited by 6 publications

(3 citation statements)

References 77 publications

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“…As pointed out in the previous sections, the determinations of tracking station coordinates and earth rotation parameters are intricately related. During the period since 1980, dramatic improvement has occurred in the ability to recover accurate earth rotation parameters from satellite laser ranging [Tapley, 1983]. Averaged results from 5-day tracking intervals are routinely reported and are used as major components of several combined earth rotation series (e.g., BIH Circular D) [Schutz et al, 1984].…”

Section: Earth Rotation Resultsmentioning

confidence: 99%

Station coordinates, baselines, and Earth rotation from LAGEOS laser ranging: 1976–1984

Tapley¹,

Schutz²,

Eanes

1985

J. Geophys. Res.

105

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Satellite laser range (SLR) measurements to LAGEOS from May 1976 to January 1984 have been used to compute earth rotation parameters and the geocentric positions of 57 laser tracking station sites occupied during this interval. The station position determinations were part of a simultaneous solution which includes LAGEOS orbit elements in 15-day arcs and earth rotation parameters in 3-day subarcs using residuals from a 7.7-year LAGEOS long arc (LLA 8402). Systematic differences between the terrestrial reference frames implied by the University of Texas station coordinate solution (LSC 8402) and by previous solutions computed at the University of Texas (UT) and at Goddard Space Flight Center (GSFC) are reviewed. The new solution resolves a 0.72 m z axis difference between the terrestrial reference system origins inferred from the GSFC solution (SL5) and the previous UT solution (LSC 8112). The implied origins of the LSC 8402 solution and the SL5 solution are consistent to less than 60 mm in all components, and after removing orientation and scale differences, the coordinates for 26 common tracking stations have an rms difference of less than 80 mm. The rms difference in baseline length for 22 station pairs used in the recent Crustal Dynamics Project very long baseline interferometry (VLBI)/SLR intercomparison experiment is 50 mm between the GSFC and UT laser solutions and 40 mm between the UT laser solution and the VLBI solution. The earth rotation parameters computed in 3-day intervals have an internal precision of 2 marc sec (62 mm at the earth's surface) for x•, and y•, and 0.15 ms (70 mm at the equator) for UT1. The estimated accuracy of the series, based on dual-baseline VLBI intercomparisons, is approximately 2 marc sec for x•, and y•, and 0.2 ms for UT1. The effects of plate motion on the determination of the secular drift in polar motion using the 7.7-year series is shown to be at the level of 1 marc sec/yr. Finally, baseline changes have been investigated by repeated station coordinate determinations using 60-day subsets of the 7.7-year interval of the LAGEOS data set. In each 60-day solution interval, orbit elements were estimated at 15-day intervals, and earth rotation parameters were determined at 5-day intervals. For the 4-year period beginning in January 1980, baseline length changes inferred by the successive 60-day solutions were found to be in general agreement with the motions predicted by the AM1-2 plate motion model of Minster and Jordan.

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Section: Earth Rotation Resultsmentioning

confidence: 99%

Station coordinates, baselines, and Earth rotation from LAGEOS laser ranging: 1976–1984

Tapley¹,

Schutz²,

Eanes

1985

J. Geophys. Res.

105

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“…Global data taken over 5-day intervals provide a suitable means for solving directly the earth's polar motion and excess length of day [Tapley, 1983]. SLR solutions (for data taken since May 1976) are routinely provided to BIH at 5-day intervals for use in the BIH Rapid Polar Motion Service series.…”

Section: Other Geophysical Quantitiesmentioning

confidence: 99%

Satellite laser ranging and its applications

Tapley

Schutz

Eanes

1985

Celestial Mechanics

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ABSTRACT. Satellite laser ranging (SLR) provides an important capability for precise orbit determination and for geophysical parameter estimation to support a number of contemporary geodynamic and oceanographic investigations. The precision of the SLR measurement has improved from the early meter-level systems to the current capabilities of a few centimeters for the best systems. The accuracy of the orbits and geophysical parameter recovery have shown an associated improvement. Polar motion with accuracies of 2 mas, station coordinates better than 10 crn, and interstation baseline rates indicative of tectonic motion are determined routinely with the current set of global SI JR data. This discussion reviews the SLR measurement, analysis approach, and some of the recent results derived from the current SLR data set.

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“…In fact, now that the accuracy in geodetic measurements is being greatly improved thanks to modern techniques (see, e.g. Tapley 1983), the incorporation of various astronomical/geodetic reference frames has become a subject of great interest and significance, as attested by two International Astronomical Union (IAU) colloquia (No. 26, 1975 andNo.…”

Section: Introductionmentioning

confidence: 99%

On the excitation of the Earth's free wobble and reference frames

Chao

1984

Geophysical Journal International

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In this paper we study the excitation of the Earth's polar motion in connection with problems that are associated with the diversity of reference frames involved in observations and theoretical computations. Thus, following the dynamics of the Earth's polar motion, the kinematics that relates observations from different reference frames are developed. The conventional procedures of studying the seismic excitation of polar motion are then re-examined accordinglysubject constantly to the question: relative to what reference frame? It is concluded that an inconsistency in the reference frames has prevailed in the literature. In particular, it is asserted that the computed change in the polar motion associated with a (sudden) seismic source is in fact what would be observed in Tisserand's mean frame. The latter has no real-world counterpart from the standpoint of observations, which are invariably made with respect to some geographic reference frame. While this inconsistency is indeed far from trivial in a philosophical sense, the resultant discrepancy is small for all practical purposes thanks to the nearly spherical configuration of the Earth.

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Polar motion and Earth rotation

Cited by 6 publications

References 77 publications

Station coordinates, baselines, and Earth rotation from LAGEOS laser ranging: 1976–1984

Station coordinates, baselines, and Earth rotation from LAGEOS laser ranging: 1976–1984

Satellite laser ranging and its applications

On the excitation of the Earth's free wobble and reference frames

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