Diurnal atmospheric forcing and temporal variations of the nutation amplitudes

Bizouard, Christian; Brzeziński, Aleksander; Petrov, S. D.

doi:10.1007/s001900050195

Cited by 41 publications

(74 citation statements)

References 17 publications

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“…Its importance is reflected in the decision by the International Earth Rotation Service (IERS) to create the Special Bureau for the Atmosphere (SBA), part of the Global Geophysical Fluids Center. Since the SBA creation [Salstein et al, 1993], the atmospheric angular momentum (AAM) time series have been available to the scientific community, further promoting dedicated studies on the atmospheric effects on Earth rotation [Bizouard et al, 1998;Hopfner, 2000]. These works are mostly related to the axial component of the AAM and the associated change in the length of day and to the equatorial components of the AAM with respect to the terrestrial frame (or the polar motion).…”

Section: Introductionmentioning

confidence: 99%

“…These atmospheric contributions to the prograde annual nutation have been empirically evaluated from the nutation data. They can also be computed from the atmospheric data by using two different approaches: the torque approach [Dehant et al, 1996;Gegout et al, 1998] but without taking into account a friction torque and the angular momentum approach [see, e.g., Bizouard et al, 1998]. The first method consists of computing the gravitational, pressure, and friction torques of the atmosphere acting on the solid Earth.…”

Section: Introductionmentioning

confidence: 99%

“…[5] The results of Bizouard et al [1998] have the right order of magnitude with respect to the residuals between observed and computed nutation. The purpose of this paper is to study the robustness of the evaluation of the atmospherically induced nutation contribution from AAM series.…”

Section: Introductionmentioning

confidence: 99%

“…[7] The contributions to the corresponding nutation components are then computed using a transfer function for the nonrigid Earth and a method similar to the one used by Bizouard et al [1998]. We show that the magnitude of the atmospheric effects on nutation is above the VLBI observation precision, stressing the necessity to incorporate the atmospheric effects in the nutation modeling.…”

Section: Introductionmentioning

confidence: 99%

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Atmospheric excitation of the Earth's nutation: Comparison of different atmospheric models

et al. 2002

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[1] Using the angular momentum approach, the effect of the atmosphere on the Earth's nutation is evaluated from five atmospheric circulation models. Five nutation frequencies are considered: the annual and semiannual prograde and retrograde and the terannual prograde. The atmospheric effect on the 18.6-year nutation is also evaluated from the only model that gives a long enough homogeneous series. The results obtained from the different models and a noninverted barometer ocean model are intercompared and compared with the residuals between the observed and computed nutations. The evaluation of the atmospheric effect on the Earth's nutation is shown to be above the observation precision, particularly at the annual frequency (prograde and retrograde) and the semiannual prograde frequency but is highly dependent on the model used, strengthening the importance of having a correct estimation for the atmospheric effects on nutation. The time evolution of the atmospheric excitation of the nutation is also studied, using a wavelet analysis and a sliding-window least squares method. We show that the fluctuations of the excited amplitude are above the level of precision of the observation.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Atmospheric excitation of the Earth's nutation: Comparison of different atmospheric models

et al. 2002

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“…As the nutation modeling contains only permanent predictable effects, the FCN is not included in IAU 2000A and therefore appears in the residuals. Other unpredictable effects come from the variable atmospheric and oceanic forcing which induces time varying nutation amplitudes of about 80 µas for the annual term (Bizouard et al 1998). Some theoretical predictable effects are taken into account in the IAU 2000A precessionnutation model whereas they were not included in the previous models.…”

Section: Introductionmentioning

confidence: 99%

Effects of zonal deformations and the Earth's rotation rate variations on precession-nutation

Lambert¹,

Capitaine²

2004

A&A

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Abstract. Because of their importance in the accurate modeling of the Earth's orientation in space, some non-negligible predictable effects on precession-nutation are investigated. This paper considers the coupling effects between the axial and the equatorial components of the Earth's rotation vector in the dynamical equations, and the effects of the second order lunisolar torque due to the Earth's zonal deformations. Firstly, the coupling effects are shown to contribute for less than 0.1 µas and are therefore negligible. Secondly, we demonstrate that the 0.7 mas contribution of the rotation rate variations due to zonal tides to the nutation in obliquity deduced by Bretagnon et al. (2000, Proc. IAU Coll., 180, 230; 2001, Celest. Mech. Dyn. Astr., 80, 177) is an artefact which comes from an incomplete way of taking into account the effect of the rotation rate variations. The net contribution is shown to be negligibly small. Thirdly, for an Earth model with an elastic mantle and decoupled liquid core, the contribution of the second-order lunisolar torque due to the Earth's zonal deformations is shown to be 207.9 µas and -9.7 µas on the 18.6-year nutation respectively in longitude and in obliquity, and a correction of -4925.9 µas/century on the precession in longitude.

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Lunar influence on equatorial atmospheric angular momentum

2014

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This study investigates the relationship between the equatorial atmospheric angular momentum oscillation in the nonrotating frame and the quasi-diurnal lunar tidal potential. Between 2 and 30 days, the corresponding equatorial component, called Celestial Atmospheric Angular Momentum (CEAM), is mostly constituted of prograde circular motions, especially of a harmonic at 13.66 days, a sidelobe at 13.63 days, and of a weekly broadband variation. A simple equilibrium tide model explains the 13.66 day pressure term as a result of the O 1 lunar tide. The powerful episodic fluctuations between 5 and 8 days possibly reflect an atmospheric normal mode excited by the tidal waves Q 1 (6.86 days) and 1 (7.095 days). The lunar tidal influence on the spectral band from 2 to 30 days is confirmed by two specific features, not occurring for seasonal band dominated by the solar thermal effect. First, Northern and Southern Hemispheres contribute equally and synchronously to the CEAM wind term. Second, the pressure and wind terms are proportional, which follows from angular momentum budget considerations where the topographic and friction torques on the solid Earth are much smaller than the one resulting from the equatorial bulge. Such a configuration is expected for the case of tidally induced circulation, where the surface pressure variation is tesseral and cannot contribute to the topographic torque, and tidal winds blow only at high altitudes. The likely effects of the lunar-driven atmospheric circulation on Earth's nutation are estimated and discussed in light of the present-day capabilities of space geodetic techniques.

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Diurnal atmospheric forcing and temporal variations of the nutation amplitudes

Cited by 41 publications

References 17 publications

Atmospheric excitation of the Earth's nutation: Comparison of different atmospheric models

Atmospheric excitation of the Earth's nutation: Comparison of different atmospheric models

Effects of zonal deformations and the Earth's rotation rate variations on precession-nutation

Lunar influence on equatorial atmospheric angular momentum

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