Secular variation of Earth's gravitational harmonic J2 coefficient from Lageos and nontidal acceleration of Earth rotation

Yoder, C. F.; Williams, J. G.; Dickey, J. O.; Schutz, B. E.; Eanes, R. J.; Tapley, Byron D

doi:10.1038/303757a0

Cited by 351 publications

(175 citation statements)

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“…Taking into account the tidal braking of the Earth's spin, which is known from precise laser ranging observations of the recession of the Moon, Stephenson and Morrison [1995] inferred an average non-tidal acceleration of 1.6 (±0.4) × 10 −22 rad s −2 , which corresponds to a rate of change in the oblateness of the Earth, as measured by J 2 , of −3.5 (±0.8) × 10 −11 yr −1 . The advent of the space age also enabled the precise study of the Earth's gravitational field, in particular through the analysis of variations existing in its zonal components, which are tightly connected to the rotational rate of the planet [Yoder et al, 1983]. Peltier [1983] demonstrated this effect to be explicable in terms of the glacial isostatic adjustment process.…”

Section: Earth Rotation and The Late Quaternary Ice-agementioning

confidence: 99%

GRACE era secular trends in Earth rotation parameters: A global scale impact of the global warming process?

Roy

Peltier

2011

Geophys. Res. Lett.

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Recent trends in the two primary anomalies in the rotational state of the planet are analyzed in detail, namely those associated with the speed and direction of polar wander and with the non‐tidal acceleration of the rate of axial rotation (via the measurement of the changing oblateness of the Earth's shape). It is demonstrated that a significant change in the secular trends in both of these independent parameters became evident subsequent to approximately 1992. It is suggested that both parameters might have come to be substantially influenced by mass loss from both the great polar ice sheets, and from the very large number of small ice‐sheets and glaciers that are also being influenced by the global warming phenomenon. The modern values for the secular drifts in those parameters that we estimate are appropriate to the period during which measurements have been made by the satellites of the Gravity Recovery and Climate Experiment (GRACE). These changes in secular rates might greatly assist in understanding why the GRACE‐inferred values of the time derivatives of the degree two and order one Stokes coefficients differ so significantly from those associated with Late Quaternary ice‐age influence.

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Section: Earth Rotation and The Late Quaternary Ice-agementioning

confidence: 99%

GRACE era secular trends in Earth rotation parameters: A global scale impact of the global warming process?

Roy

Peltier

2011

Geophys. Res. Lett.

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“…Since angular momentum is conserved in the absence of applied torques, it is then clear that the rate of axial rotation must increase (see Figure 11). Beginning with the analyses of laser ranging data to the Laser Geodynamics Satellite (LAGEOS) by Yoder et al [1983], presented simultaneously with the appearance of theoretical predictions of the GIA effect by Peltier [1982,1983], the validity of the eclipse-based inference of the magnitude of the nontidal acceleration of rotation was clearly established. Many estimates of the nontidal acceleration based upon analyses of SLR data have now appeared (the effect observed is an acceleration in the node of the orbit; see Figure 11), and these are tabulated on Figure 12a where they are all expressed in terms of Jr 2.…”

Section: Astronomical Signatures Of the Ice Age Cyclementioning

confidence: 99%

Postglacial variations in the level of the sea: Implications for climate dynamics and solid‐Earth geophysics

Peltier¹

1998

Reviews of Geophysics

543

538

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Abstract. Throughout the latter half of the Pleistocene epoch of Earth history, beginning --•900 kyr ago, the climate system has been dominated by an intense oscillation between full glacial and interglacial conditions. During each glacial stage, global sea level fell by --•120 rn on average, as extensive ice sheets formed and thickened on the surfaces of the continents at high northern (primarily) and southern latitudes. Within each cycle this glaciation phase lasted --•90 kyr and was followed by a much more rapid deglaciation event which terminated after --•10 kyr and which returned the system to the interglacial state. The period of the canonical glacial cycle has remained very close to 100 kyr since its inception in mid-Pleistocene time. Because of the magnitude of the mass that was redistributed over the surface of the Earth during each such glacial cycle and because of the viscoelastic nature of the rheology of the planetary mantle, these shifts in surface mass load induced variations in the shape of the planet that have been indelibly transcribed into the geological record of sea level variability. Indeed, the geological, geophysical, and even astronomical signatures of this process, which is continuing today, are now being measured with unprecedented precision using the methods of space geodesy and have thereby begun to provide important new scientific insight and understanding, both of the interior of the solid Earth and of the climate system variability with which the ice ages themselves are associated. In this article my purpose is to bring together, in a single review, an assessment of where we currently stand scientifically with regard to understanding both of these aspects of the ice ages. Although the discussion will not address in any detail the fascinating issue of ice age climate, since this topic is sufficiently complex of itself to require a detailed review of its own, I will nevertheless attempt to briefly summarize the current state of understanding of the physical processes that are responsible for the occurrence of the ice age cycle, by way of providing a more complete context in which to appreciate the main lines of argument that will be developed.

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“…Since the rate of change due to the action of tidal friction alone may be accurately estimated on the basis of the observed rate of recession of the Moon, using lunar laser ranging, and since the net increase in the length of day as a function of time may be inferred on the basis of the analysis of ancient eclipse observations [e.g., Stephenson and Morrison, 1995], one may infer the action of a nontidal component of the acceleration of rotation, which acts so as to slightly reduce the rate of increase of the length of day due to tidal friction, in the amount (1.6 ± 0.4) Â 10 À22 rad s À1 over the past $2500 years. This nontidal acceleration is equivalent to a value for the time dependence of the degree 2 zonal coefficient in the spherical harmonic expansion of Earth's gravitational field, commonly represented in terms of a parameter denoted _ J 2 , of approximately (À2.67 ± 0.15) Â 10 À11 yr À1 [e.g., Yoder et al, 1983;Cheng et al, 1989;Cheng and Tapley, 2004]. Although a transient departure from this long timescale trend has been noted in apparent association with an especially strong El Niño -Southern Oscillation event [Cox and Chao, 2002], following this event, the system recovered in such a way that the initial trend was reestablished.…”

Section: Introductionmentioning

confidence: 99%

On the origins of Earth rotation anomalies: New insights on the basis of both “paleogeodetic” data and Gravity Recovery and Climate Experiment (GRACE) data

2009

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The theory previously developed to predict the impact on Earth's rotational state of the late Pleistocene glaciation cycle is extended. In particular, we examine the extent to which a departure of the infinite time asymptote of the viscoelastic tidal Love number of degree 2, “k2T,” from the observed “fluid” Love number, “kf,” impacts the theory. A number of tests of the influence of the difference in these Love numbers on theoretical predictions of the model of the glacial isostatic adjustment (GIA) process are explored. Relative sea level history predictions are shown not to be sensitive to the difference even though they are highly sensitive to the influence of the changing rotational state itself. We also explore in detail the accuracy with which the Gravity Recovery and Climate Experiment (GRACE) satellite system is able to observe the global GIA process including the time‐dependent amplitude of the degree 2 and order 1 spherical harmonic components of the gravitational field, the only components that are significantly influenced by rotational effects. It is explicitly shown that the GRACE observation of these properties of the time‐varying gravitational field is sufficiently accurate to rule out the values predicted by the ICE‐5G (VM2) model of Peltier (2004). However, we also note that this model is constrained only by data from an epoch during which modern greenhouse gas induced melting of both the great polar ice‐sheets and small ice sheets and glaciers was not occurring. Such modern loss of grounded continental ice strongly influences the evolving rotational state of the planet and thus the values of the degree 2 and order 1 Stokes coefficients as they are currently being measured by the GRACE satellite system. A series of sensitivity tests are employed to demonstrate this fact. We suggest that the accuracy of scenarios for modern land ice melting may be tested by ensuring that such scenarios conform to the GRACE observations of these crucial time‐dependent Stokes coefficients.

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Secular variation of Earth's gravitational harmonic J2 coefficient from Lageos and nontidal acceleration of Earth rotation

Cited by 351 publications

References 21 publications

GRACE era secular trends in Earth rotation parameters: A global scale impact of the global warming process?

GRACE era secular trends in Earth rotation parameters: A global scale impact of the global warming process?

Postglacial variations in the level of the sea: Implications for climate dynamics and solid‐Earth geophysics

On the origins of Earth rotation anomalies: New insights on the basis of both “paleogeodetic” data and Gravity Recovery and Climate Experiment (GRACE) data

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