Postglacial rebound observed by lageos and the effective viscosity of the lower mantle

Rubincam, David Parry

doi:10.1029/jb089ib02p01077

Cited by 161 publications

(86 citation statements)

References 48 publications

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“…Recent rebound of the Earth's shape after the last glacial period occurs at a measured rate J2 =-2.6"10 -11 year (Rubincam 1984). In case the same rate was typical for the Late Pleistocene, then 35 thous, years BP, ie 15-25 thous.…”

Section: Resultsmentioning

confidence: 95%

Marine terraces as indicators of global geoidal and hydrological changes

1992

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Spatial pattern analysis of marine terrace elevations from 40-30 thous, years BP was used to reconstruct sea level/geoid surface and geoid parameters during that time. The polar flattening of geodetic ellipsoid was lower than its present value (1/298.81 and 1/298.26 respectively because of glacial-induced mass redistribution. Increase in polar stress occurred during the last 30 thous, years was possibly driven by pertubation brought to the gravitational field by disintergration of polar ice sheets in the Northern hemisphere. But the polar flattening value becomes only half-restored during the last deglacial hemicycle. So repetitive glacial advances during Pleistocene acted as a global "pump" for uncondensed zones at the upper/ lower mantle boundary. Dissipation of tidal energy is an order of magnitude less intensive in its Earth's rotation effect.

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Section: Resultsmentioning

confidence: 95%

Marine terraces as indicators of global geoidal and hydrological changes

1992

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“…The periodic perturbations in the node St, for instance, are far below the residuals level of about 0.03 arc sec of the satellite laser ranging data (Rubincam, 1984, Figure 2). Also, the semimajor axis a is Perturbed at the 5mm level over a period of 833 da y s. This is smaller than the effect of some indivi,lual solar eclipses on the orbit of Lageos.…”

Section: Discussionmentioning

confidence: 99%

Earth albedo and the orbit of Lageos

Rubincam

Weiss²

1986

Celestial Mechanics

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Abstract. The long-period perturbations in the ornit of the Lageos satellite due to the earth's albedo have been found using a new analytical formalism. The earth is assumed to be a sphere whose surface diffusely reflects sunlight according to Lambert's law. Specular reflection is not considered. The formalism is based on spherical harmonics; it produces equations which hold regardless of whether the terminator is seen by the satellite or not. Specializing; to the case of a realistic zonal albedo shows that Lageos' orbital semimajor axis changes periodically by only a few millimeters and the eccentricity by one part in 10 5 . The longitude of the node increases secularly by about 3 x 10 -4 arc sec yr -1 . The effect considered here can explain neither the secular decay of 1.1 mm d ly -1 in the semimajor axis nor the observed along-track variations ;n acceleration of order 2 x 10 -1 ` ms--2.

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“…The zonally symmetric part of the rebound is thought to be responsible for the secular change in the J2 and other gravitational harmonics of the Eax• as seen by LAGEOS and other satellites [Yoder et al, 1983;Rubincam, 1984], and the secular polar motions come from the P21 harmonic of this deformation [Peltier, 1988]. The time constants for the rebound are so long (thousands of years) that even over centuries the polar wander appears to be a linear function of time.…”

Section: Secular and Decadal Polar Motionsmentioning

confidence: 96%

Variations in the orientation of the Earth

Eubanks¹

1993

Geodynamics Series

221

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During the period of the Crustal Dynamics Project the accuracy and resolution of Earth orientation measurements both improved by almost two orders of magnitude. These technical advances were accompanied by a corresponding increase in the sophistication of the analysis and interpretation of such data, and by considerable advances in understanding. This paper reviews recent progress in Earth rotation research and assesses the current state of knowledge in the field, concentrating in particular on developments in measurement technology, the theory of orientation changes, and studies of the excitation of rotational variations by irregular fluid motions in the atmosphere, oceans and liquid outer core. 1. INTRODUC7•ON The Crustal Dynamics Project, or CDP [Coates et al., 1985], coincided with a considerable increase in the accuracy and sophistication of Earth rotation research, and had a large role in causing these advances in the field. The CDP was established by the U.S. National Aeronautics and Space Administration (NASA) in 1979, and had as one of its scientific objectives the improvement of "knowledge and understanding of (the) rotational dynamics of the Earth and their possible correlation with earthquakes, plate motions and other geophysical phenomena..." [Coates et al., 1985]. These goals have been substantially met. Space geodetic techniques of unprecedented accuracy and precision have been developed and applied to problems of Earth rotation, to the point that, while at the beginning of the Project variations of Earth rotation with amplitudes of meters and periods of months were just becoming visible (see Figure 1, from Feissel and Gambis [1980]), by the end of the Project (Figure 2) variations with amplitudes of centimeters and periods less than a day are clearly visible [Eubanks et al., 1991b; Brosche et al., 1991; Herring and Dong, 1991; Lichten et ed., 1992; Herring, 1993]. Note the great increase in scale between the two Figures; all of Figure 2 wotfid fit inside one of the asterisks of Figure 1, hadicative of the advance of the state of the art during the lifetime of the Project. The proven causes of Earth rotation changes can be divided into the gravitational interaction between the Earth and other celestial bodies (primarily the Sun and the Moon), and forcings from geophysical fluid dynamics. Geophysical fluid motions tend to have "red" noise power spectra, i.e. to have a general decline in Contributions of Spaco Geodesy to Goodynamics: Earth Dynamics Goodynamics 24 This paper is not subject to U.S. copyright. Published in 1993 by the American Geophysical Union. power with increasing frequency [Agnew, 1992], and increases in the resolution and accuracy of the geodetic data will generally restfit in the detection of smaller motions at higher frequencies. A major thrust of the Project was thus to improve the techniques used to observe rotational variations. Routine determinations of Earth orientation using Very Long Baseline Interferometry (VLBI) [Carter et al., 1985; Robertson et al., 1985a, b; Herring, ...

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Postglacial rebound observed by lageos and the effective viscosity of the lower mantle

Cited by 161 publications

References 48 publications

Marine terraces as indicators of global geoidal and hydrological changes

Marine terraces as indicators of global geoidal and hydrological changes

Earth albedo and the orbit of Lageos

Variations in the orientation of the Earth

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