Abstract
This paper reviews how the study of the surface gravity changes is able to provide useful information on the Earth's structure and global dynamics. The spectral range which is observable with superconducting gravimeters is broad and goes from the seismic frequency band to periods longer than one year. We first investigate the seismic and sub-seismic bands with a special attention paid to the gravity detection of core modes in the liquid core and to the Slichter mode of translation of the solid inner core. In the tidal bands, we show how accurate measurements allow us to infer constraints on various phenomena such as mantle (an-)elasticity, as well as ocean and atmospheric loading. The observation of the Free Core Nutation resonance in the diurnal frequency band is reviewed and indirectly suggests an increase in the ellipticity of the core-mantle boundary with respect to its hydrostatic value. A similar resonance is also theoretically predicted in the diurnal band for the rotation of the solid inner core (Free Inner Core Nutation) but we show that its detection is much more difficult because of the small amplitude and lack of a nearby tidal frequency. Oceanic and atmospheric loading mechanisms induce gravity changes over a wide spectral range and we present some recent progress in this field. Finally, because superconducting gravimeters have high calibration stability and small long-term instrumental drift, they can easily measure longperiod gravity variations due to polar motion and hydrogeology.
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Achilli, V., Baldi, P., Casula, G., Errani, M., Focardi, S., Guerzoni, M., Palmorani, F. and Raguni, G.: 1995, A calibration system for superconducting gravimeters, Bull. Géodésique 69, 73–80.
Agnew, D.C.: 1995, Ocean-load tides at the South Pole: a validation of recent ocean-tide models, Geophys. Res. Lett. 22(22), 3063–3066.
Aldridge, K. and Lumb, L.I.: 1987, Inertial waves identified in the Earth's fluid outer core, Nature 325, 421–423.
Aldridge, K. and Cannon, W.: 1993, A search for evidence of short period polar motion in VLBI and Supergravimetry observations, in Dynamics of the Earth's Deep Interior and Earth Rotation, Geophys. Monograph Series, Am. Geophys. Union, 72, vol. 12, pp. 17–24.
Amalvict, M., Hinderer, J., Francis, 0. and Mäkinen, J.: 1998, Comparisons between absolute (AG) and superconducting (SG) gravimeters. In: R. Forsberg, M. Feissel and R. Dietrich (eds), Geodesy on the Move. Gravity, Geoid, Geodynamics, and Antarctica. JAG Scientific Assembly, IAG Symposia 119, 24–29.
Andersen, O.B., Woodworth, P.L. and Flather, R.A.: 1995, Intercomparison of recent ocean tide models, J. Geophys. Res. 100(C12), 25261–25282.
Banka, D. and Crossley, D.: 1995, SG record at Cantley, Canada: the short period part of the specrum, Bull. Inf. Marées Terrestres 122, 9148–9160.
Banka, D. and Crossley, D.: 1999, Noise levels of superconducting gravimeters at seismic frequencies, Geophys. J. Int., submitted.
Banka, D., Jentzsch, G.and Crossley, D.: 1998, Investigations of superconducting gravimeter records in the frequency range of the free oscillations of the Earth - the noise amplitude, in B. Ducarme and P. Pâquet, eds. Proc. 13th Int. Symp. Earth Tides. Brussels, pp. 641–649.
Baker, T., Edge, R.J.and Jeffries, G.: 1991, Tidal gravity and ocean tide loading in Europe, Geophys. J. Int. 107, 1–11.
Bower, D.R. and Courtier, N.: 1998, Precipitation effects on gravity measurements at the Canadian absolute gravity site, Phys. Earth Planet Int. 106, 353–369.
Boy, J.P., Hinderer, J. and Gégout, P.: 1998a, Global atmospheric loading and gravity, Phys. Earth Planet Int. 109, 161–177.
Boy, J.P., Hinderer, J. and Gégout, P.: 1998b, The effect of atmospheric loading on gravity, in B. Ducarme and P. Paquet, eds, Proc. 13th Int. Symp. Earth Tides, Brussels, pp. 439–446.
Buffett, B.: 1992,.Constraints on magnetic energy and mantle conductivity from the forced nutations of the Earth, J. Geophys. Res. 97(B13), 19581–19597.
Cartwright, D.E. and Tayler, R.J.: 1971, New computations of the tide-generating potential, Geophys. J. R. Astr. Soc. 23, 45–74.
Cartwright, D.E. and Edden, A.C.: 1973, Corrected tables of tidal harmonics, Geophys. J. R. Astr. Soc. 33, 253–264.
Chao, B.F., Merriam, J. and Tamura, Y.: 1995, Geophysical analysis of zonal tidal signals in length-of-day, Geophys. J. Int. 122, 765–775.
Courtier, N., Ducarme, B., Goodkind, J., Hinderer, J., Imanishi, Y., Seama, N., Sun, H., Merriam, J., Bengert, B. and Smylie, D.E.: 2000, Global superconducting gravimeter observations and the search for the translational modes of the inner core, Phys. Earth Planet Int. 117, 3–20.
Crossley, D.J.: 1988, The excitation of core modes by earthquakes, in Structure and Dynamics of Earth's Deep Interior, Geophys. Monograph. Ser., Am. Geophys. Union 46, 41–50.
Crossley, D.: 1993, The gravity effect of core modes for a rotating Earth, J. Geomag. Geoelectr. 45, 1371–1381.
Crossley, D.J. and Smylie, D.E.: 1975, Electromagnetic and viscous damping of core oscillations, Geophys. J. 42, 1011–1033.
Crossley, D. and Rochester, M.: 1980, Simple core undertones, Geophys. J. Roy. astr. Soc. 60, 129–161.
Crossley, D.J. and Rochester, M.: 1992, The subseismic approximation in core dynamics, Geophys. J. Int. 108, 502–506.
Crossley, D. and Hinderer, J.: 1995, Global Geodynamic Project-GGP: Status report 1994, in Proc. Second JAG Workshop on Non-tidal gravity changes: Intercomparison between absolute and superconducting gravimeters, Cahiers du Centre Europen de Géodynamique et de Sismologie, Luxemburg 11, 244–274.
Crossley, D.J., Hinderer J. and Legros, H.: 1991, On the excitation, detection and damping of core modes, Phys. Earth Planet. Int. 116, 68–97.
Crossley, D., Rochester M. and Peng, Z.: 1992, Slichter modes and Love numbers, Geophys. Res. Lett. 19, 1679–1682.
Crossley, D., Jensen, O. and Hinderer, J.: 1995, Effective barometric admittance and gravity residuals, Phys. Earth Planet. Int. 90, 221–241.
Crossley, D., Su, X, and van Dam, T.: 1998, Comprehensive analysis of 2 years of SG data from Table Mountain, Colorado, in B. Ducarme and P. Paquet, eds. Proc. 13th Int. Symp. Earth Tides. Brussels, pp. 659–668.
Crossley, D. and Su, X.: 1998, Analysis of superconducting gravimeter data from Table Mountain, Colorado, Geophys. J. Int. 135, 835–844.
Crossley, D., Hinderer, J., Casula, G., Francis, O., Hsu, H.-T., Imanishi Y., Jentsch G., Kaarianen, J., Merriam, J., Meurers, B., Neumeyer J., Richter, B., Shibuya, K., Sato, T. and van Dam, T.: 1999, Network of superconducting gravimeters benefits a number of disciplines, EOS, Trans. Am. Geophys. U. 80, 121–126.
Cummins, P. and Wahr, J.: 1993, A study of the Earth's core nutation using gravity data, J. Geophys. Res. 98, 2091–2104.
Cummins, P., Wahr, J., Agnew, D. and Tamura, Y.: 1991, Constraining core undertones using stacked IDA gravity records, Geophys. J. Int. 106, 189–198.
Dahlen, F.A. and Sailor, R.V.: 1979, Rotation and elliptical splitting of the free oscillations of the Earth, Geophys. J. R. astr. Soc. 58, 609–623.
Defraigne, P., Dehant, V. and Hinderer, J.: 1994, Stacking gravity tide measurements and nutation observations in order to determine the complex eigenfrequency of the nearly diurnal free wobble, J. Geophys. Res. 99(B5), 9203–9213.
Defraigne, P., Dehant, V. and Hinderer, J.: 1995, Correction to “Stacking gravity tide measurements and nutation observations in order to determine the complex eigenfrequency of the nearly diurnal free wobble”, J. Geophys. Res. 100(B2), 2041–2042.
Defraigne, P., Dehant, V. and Wahr, J.M.: 1996, Internal loading of an inhomogeneous compressible earth with phase boundaries, Geophys. J. Int. 125, 173–192.
Dehant, V. and Ducarme, B.: 1987, Comparison between the theoretical and observed tidal gravimetric factors, Phys. Earth planet. Int. 49, 192–212.
Dehant, V. and Zschau, J.: 1989, The effect of mantle inelasticity on tidal gravity: a comparison between the sherical and the elliptical Earth model, Geophys. J. 97, 549–555.
Dehant, V., Ducarme, B. and Defraigne, P.: 1993a, New analysis of the Superconducting gravimeter data of Brussels, in Dynamics of the Earth's Deep Interior and Earth Rotation, Geophys. Monograph Series, Am. Geophys. Union, 72, 35–44.
Dehant, V., Hinderer, J., Legros, H. and Lefftz, M.: 1993b, Analytical approach to the computations of the Earth, the outer core and the inner core rotational motions, Phys. Earth Planet. Int. 76, 259–282.
Dehant, V., Bizouard, C., Hinderer, J., Legros, H. and Greff-Lefftz, M.: 1996, On atmospheric pressure perturbations on precession and nutations, Phys. Earth Planet. Int. 96, 25–39.
Delcourt-Honorez, M.: 1995, Hydrogeological effects on the local gravity, in Proc. Second JAG Workshop on Non-tidal gravity changes: Intercomparison between absolute and superconducting gravimeters, Cahiers du Centre Europen de Géodynamique et de Sismologie, Luxemburg 11, 161–168.
De Vries, D. and Wahr, J.: 1991, The effects of the solid inner core and nonhydrostatic structure on the Earth's forced nutations and Earth tides, J. Geophys. Res. 96(B5), 8275–8293.
Dickman, S.: 1988, Theoretical investigation of the oceanic inverted barometer. hypothesis, J. Geophys Res. 93, 14941–14946.
Dong, D., Gross, R.S. and Dickey, J.O.: 1996, Seasonal variations of the Earth's gravitational field; air analysis of atmospheric pressure, ocean tidal, and surface water excitation, Geophys. Res. Lett. 23(7), 725–728.
Dittfeld, H.J.: 1998, The long-periodic constituents in the SG TT70 record at Potsdam, in B. Ducarme and P. Pâquet, eds., Proc. 13th Int. Symp. Earth Tides. Brussels, pp. 599–605.
Ducarme, B. and Melchior, P.: 1998, Fine structure of the tidal spectrum: eight lunar modal waves and third degree waves derived from the 14 year series of observations with the superconducting gravimeter GWR/T3 in B. Ducarme and P. Pâquet, eds., Proc. 13th Int. Symp. Earth Tides, Brussels, pp. 347–356.
Eubanks, M., Steppe, J., Dickey, J. and Callahan, P.: 1985, A spectral analysis of the Earth's angular momentum budget, J. Geophys. Res. 90(B7), 5385–5404.
Eubanks, T.M., Steppe, J.A., Dickey, J.O., Rosen, R.D. and Salstein, D.A.: 1988, Causes of rapid motions of the Earth's pole, Nature 334, 115–119.
Florsch, N., Hinderer, J., Crossley, D., Legros, H. and Valette, B.: 1991, Preliminary spectral analysis of the residual signal of a superconducting gravimeter for periods shorter than one day, Phys. Earth Planet. Int. 68, 85–96.
Florsch, N., Chambat, F., Hinderer, J. and Legros, H.: 1994, A simple method to retrieve the complex eigenfrequency of the Earth's nearly diurnal free wobble; application to the Strasbourg superconducting gravimeter data, Geophys. J. Int. 116, 53–63.
Florsch, N., Legros, H. and Hinderer, J.: 1995a, The search for weak harmonic signals in a spectrum with applications to gravity data, Phys. Earth Planet. Int. 90, 197–210.
Florsch, N., Hinderer, J. and Legros, H.: 1995b, Identification of quarter-diurnal tidal waves in superconducting gravimeter data, Bull. Int. Marées Terr. 22, 9189–9198.
Florsch, N., Hinderer, J. and Legros, H.: 1995c,.Generalyzed and Bayesian inversions of the FCN parameters from gravity data, paper presented at the XX EGS General Assembly, Hamburg.
Florsch, N. and Hinderer, J.: 1998, Estimation of the Free Core Nutation Q factor from tidal analysis, in B. Ducarme and P. Pâquet, eds., Proc. 13th Int. Symp. Earth Tides, Brussels, pp. 315–322.
Florsch, N. and Hinderer, J.: 2000, Bayesian estimation of the Free Core Nutation parameters from the analysis of precise tidal gravity data, Phys. Earth Planet. Int. 117, 21–35.
Forte, A., Woodward, R. and Dziewonski, A.: 1994, Joint inversions of seismic and geodynamic data for models of three-dimensional mantle heterogeneity, J. Geophys. Res. 99, 21857–21877.
Francis, O.: 1996, Calibration of the CO21 superconducting gravimeter in Membach (Belgium) using one month of absolute gravity measurements, in IAG Symposia vol. 117, Gravity, Geoid, and Marine Geodesy, Segawa et al., eds., Springer-Verlag Berlin, pp. 212–219.
Francis, O. and Meichior, P.: 1996, Tidal loading in south western Europe: a test area, Geophys. Res. Lett. 23, 2251–2254.
Freedman, A.P., Ibanez-Meier, R., Herring, T., Lichten, S.M. and Dickey, J.O.: 1994, Subdaily Earth rotation during the Epoch 92 Campaign, Geophys. Res. Lett. 21(9), 769–782.
Freybourger, M., Hinderer, J. and Trampert, J.: 1997, Comparative study of superconducting gravimeters and broadband seismometers STS-1/Z in seismic and subseismic frequency bands, Phys. Earth Planet. Int. 101, 203–217.
Friedlander, S. and Siegmann, W.L.: 1983, Effects of dissipation on internal waves in a contained rotating stratified fluid, Geophys. Astr. Fluid Dyn. 19, 267–291.
Kroner, C. and Jentzsch, G.: 1999, Comparison of different barometric pressure reductions for gravity data and resulting consequences, Phys. Earth Planet. Int. 115, 205–218.
Fukao, Y. and Suda, N.: 1989, Core modes of the Earth's free oscillations and structure of the inner core, Geophys. Res. Lett. 16(5), 401–404.
Fukuda, Y. and Sato, T.: 1997, Gravity effects of sea level variation at the superconducting Gravimeter sites, estimated from ERS-1 and Topex-Poseidon altimeter data, in JAG Symposia vol. 117, Gravity, Geoid, and Marine Geodesy, Segawa et al., eds., Springer-Verlag Berlin, pp. 107–114.
Gegout P. and Cazenave, A.: 1993, Temporal variations of the Earth gravity field for 1985-1989 derived from Lageos, Geophys. J. Int. 114, 347–359.
Gegout, P., Hinderer, J., Legros, H., Greff, M. and Dehant, V.: 1998, On the influence of atmospheric pressure on the free and forced nutational motions of the Earth, Phys. Earth Planet. Inter. 106, 337–351.
Goodkind, J., 1986, Continuous measurements of non-tidal variations of gravity, J. Geophys. Res. 91, 9125–9134.
Goodkind, J.: 1996, Test of theoretical solid earth and ocean gravity tides, Geophys. J. Int. 125, 106–114.
Goodkind, J.: 1999, The superconducting gravimeter, Review of Scientific Instruments 70(11), 4131–4152.
Greff, M. and Legros, M.: 1996, Viscoelastic mantle density heterogeneity and core-mantle topography, Geophys. J. Int. 125, 567–576.
Gwinn, T., Herring, T. and Shapiro, I.: 1986, Geodesy by Radio Interferometry: Studies of the forced nutations of the Earth: 2. Interpretation, J. Geophys. Res. 91(B5), 4755–4765.
Haas, P. and Schuh, H.: 1996, Determination of frequency dependent Love and Shida numbers from VLBI data, Geophys. Res. Lett. 23(12), 1509–1512.
Hager, B., Clayton, R., Richards, M., Corner, R. and Dziewonski, A.: 1985, Lower mantle heterogeneity, dynamic topography and the geoid, Nature 313, 541–545.
Harnish, M., Harnish, G., Richter, B. and Schwahn, W.: 1998, Estimation of polar motion effects from time series recorded by superconducting gravimeters, in B. Ducarme and P. Pâquet, eds, Proc. 13th Int. Symp. Earth Tides, Brussels, pp. 511–518.
Hartmann, T., and Wenzel, H.G.: 1995, The HW95 tidal potential catalogue, Geophys. Res. Lett. 22(24), 3553–3556.
Haurwitz, B. and Cowley, A.D.: 1973, The diurnal and semi-diurnal barometric oscillations, global distribution and annual variation, Pageoph. 102, 193–222.
Herring, T. and Dong, D.: 1994, Measurement of diurnal and semi-diurnal rotation variations and tidal parameters of the Earth, J. Geophys. Res. 99, 18051–18071.
Herring, T., Gwinn, C. and Shapiro, I.: 1986, Geodesy by radiointerferometry: studies of the forced irritations of the Earth, 1, Data analysis, J. Geophys. Res. 91, 4745–4755.
Herring, T., Buffett, B., Mathews, P. and Shapiro, I.: 1991, Forced nutations of the Earth: Influence of inner core dynamics 3. Very long interferometry analysis, J. Geophys. Res. 96(B5), 8529–8273.
Hide, R.: 1969, Interactions between the Earth's liquid core and the solid mantle, Nature 222, 1055–1056.
Hinderer, J. and Legros, H.: 1989, Elasto-gravitational deformation, relative gravity changes and Earth dynamics, Geophys. J. 97, 481–495.
Hinderer, J. and Legros, H.: 1991, Gravity perturbations of annual period, in J. Kakkuri, ed., Proc. 11th Int. Symp. Earth Tides, Schweitzerbart. Verlag, Stuttgart, pp. 425–429.
Hinderer, J. and Crossley, D.: 1993, Core Dynamics and surface gravity changes, in Dynamics of the Earth' Deep Interior and Earth Rotation, Geophys. Monograph Series, Am. Geophys. Union, 72, 1–16.
Hinderer, J., Legros, H. and Amalvict, M.: 1982, A search for Chandler and nearly diurnal free wobbles using Liouville equations, Geophys. J. Roy. astr. Soc. 71, 121–132.
Hinderer, J., Legros, H., Jault, D. and Le Mouël, J.L.: 1990, Core-mantle topographic torque: a spherical harmonic approach and implications for the excitation of the Earth's rotation by core motions, Phys. Earth Planet. Int. 59, 329–341.
Hinderer, J. Florsch, N., Mäkinen, J., Legros, H. and Faller, J.E.: 1991a, On the calibration of a superconducting gravimeter using absolute gravity measurements, Geophys. J. Int. 106, 491–497.
Hinderer, J., Legros, H. and Crossley, D.: 1991b, Global Earth dynamics and induced gravity changes, J. Geophys. Res. 96, 20257–20265.
Hinderer, J., Zürn, W. and Legros, H.: 1991c, Interpretation of the strength of the nearly diurnal free wobble resonance from stacked gravity tide observations, in J. Kakkuri, ed., Proc. 11th Int. Symp. Earth Tides, Schweitzerbart. Verlag, Stuttgart, pp. 549–555.
Hinderer, J., Crossley, D. and Xu, H.: 1994a, A two year comparison between the French and Canadian superconducting gravimeter data, Geophys. J. Int. 116, 252–266.
Hinderer, J., Florsch, N. and Jensen, O.: 1994b, Investigation of FCN resonance in Superconducting Gravimeter data using a generalized nonlinear inverse method, Eos 75(44), 157.
Hinderer, J., Florsch, N. and Mäkinen, J.: 1995a, Calibration of a superconducting gravimeter from repeated absolute gravity measurements, paper presented at the XXI IUGG Gen. Assembly, Boulder, USA.
Hinderer, J., Crossley, D. and Jensen, O.: 1995b, A search for the Slichter triplet in superconducting gravimeter data, Phys. Earth Planet. Int. 90, 183–195.
Hinderer, J., Crossley, D. and Xu, H.: 1995c, The accuracy of tidal gravimetric factors and nearly diurnal free wobble resonance parameters in superconducting gravimetry, in H.T. Hsu, ed., Proc. 12th Earth Tide Symp., Beijing, pp. 289–309.
Hinderer, J., Amalvict, M., Florsch, N., Francis, O. and Mäkinen, J.: 1998a, On the calibration of superconducting gravimeters with the help of absolute gravity measurements, in B. Ducarme and P. Pâquet, eds., Proc. 13th Int. Symp. Earth Tides, Brussels, pp. 557–564.
Hinderer, J., Boy, J.P. and Legros, H.: 1998b, A 3000 day registration of the superconducting gravimeter GWR T005 in Strasbourg (France), in B. Ducarme and P. Pâquet, eds., Proc. 13th Int. Symp. Earth Tides, Brussels, pp. 617–624.
Hori, S., Fukao, Y., Kumazawa, M. and Imanishi, Y.: 1989, A new method of spectral analysis and its applications to the Earth's free oscillations: algorithm of the Sompi method, J. Geophys. Res. 94, 7535–7553.
Hsu, H.H. and Hoskins, B.: 1989, Tidal fluctuations as seen in ECMWF data, Q. J. R. Meteoro. Soc. 115, 247–264.
Imanishi, Y., Sato, T., Kumazawa, M., Ooe, M. and Tamura, Y.: 1992, Observations of seimsic core modes from a superconducting gravimeter record, Phys. Earth Planet. Int. 72, 249–263.
Jackson, B. and Slichter, L.: 1974, The residual daily tides at South Pole, J. Geophys. Res. 79(11), 1711–1715.
Jensen, O., Hinderer, J. and Crossley, D.: 1994, Search for the Slichter mode triplet and S1 seismic core modes in a superconducting gravimeter record from the June 9, 1994 Bolivian earthquake, Eos 75(44), 69.
Jensen, O., Hinderer, J. and Crossley, D.: 1995, Noise limitations in the core-mode band of superconducting gravimeter data, Phys. Earth Planet. Int. 90, 169–181.
Jiang, X. and Smylie, D.E.: 1995, A search for free core nutation modes in VLBI irritation observations, Phys. Earth Planet. Int. 90, 91–100.
Kamal and Mansinha, L.: 1992, A test of the superconducting gravimeter as a long-period seismometer, Phys. Earth Planet. Int. 71, 52–60.
Kennett, B.L.: 1998, On the density distribution within the Earth, Geophys. J. Int. 132, 374–382.
Kobayashi, N. and Nishida, K.: 1998, Continuous excitation of planetary free oscillations by atmospheric disturbances, Nature 395, 357–360.
Lambeck, K.: 1980, The Earth's variable rotation: Geophysical causes and consequences, Cambridge University Press, pp. 449.
Lambert, A. and Beaumont, C.: 1977, Nano variations in gravity due to seasonal groundwater movements: implications for the gravitational detection of tectonic movements, J. Geophys. Res. 82, 297–305.
Lambert, A., Courtier, N. and Liard, J.: 1995, Combined absolute and superconducting gravimetry: needs and results, in Proc. Second IAG Workshop on Non-tidal gravity changes: Intercomparison between absolute and superconducting gravimeters, Cahiers du Centre Europen de Géodynamique et de Sismologie, Luxemburg, 11, 97–107.
Langley, R.B., King, R.W., Shapiro, I.I., Rosen, R.D. and Salstein, D.A.: 1981, Atmospheric angular momentum and the length of day: a common fluctuation with a period near 50 days, Nature 294, 24–31.
Legros, H. and Amalvict, M.: 1989, The Earth's rotation, in Physics and evolution of the Earth's interior, vol. 4, Gravity and Low-frequency Geodynamics, ed. Teisseyre, R., Elsevier, Amsterdam, pp. 187–294.
Legros, H. and Hinderer, J.: 1991, On some perturbations of tidal waves and related nutations, in J. Kakkuri, ed., Proc. 11th Int. Symp. Earth Tides, Schweitzerbart. Verlag, Stuttgart, pp. 557–563.
Legros, H., Hinderer, J., Lefftz, M. and Dehant, V.: 1993, The influence of the solid inner core on gravity changes and spatial nutations induced by luni-solar tides and surface loading, Phys. Earth Planet. Int. 76, 283–315.
Le Provost, C., Genco, M.L., Lyard, F., Vincent, P. and Canceil, P.: 1994, Spectroscopy of the world ocean tides from a finite element hydrodynamical model, J. Geophys. Res. 99(C12), 24777–24797.
Llubes, M. and Mazzega, P.: 1996, The ocean tide gravimetric loading reconsidered, Geophys. Res. Lett. 23(12), 1481–1484.
Lognonné, P., Clévédé, E. and Kanamori, H.: 1998, Computation of seismograms and atmospheric oscillations by normal-mode summation for a spherical earth model with realistic atmosphere, Geophys. J. Int. 135, 388–406.
Loyer, S., Hinderer, J. and Boy, J.P.: 1999, Determination of the gravimetric factor at the Chandler period from Earth's orientation data and superconducting gravimetry observations, Geophys. J. Int. 136, 1–7.
Lumb, I. and Aldridge, K.: 1991, On viscosity estimates for the Earth's fluid outer core and coremantle coupling, J. Geomag. Geoelectr. 43, 93–110.
Mäkinen, J. and Tattari, S.: 1990, The influence of variation in subsurface water storage on observed gravity, in J. Kakkuri, ed., Proc. 11th Int. Symp. Earth Tides, Schweitzerbart. Verlag, Stuttgart, pp. 457–471.
Mansinha, L., Smylie, D. and Sutherland, B.: 1990, Earthquakes and the spectrum of the Brussels superconducting gravimeter data for 1982-1986, Phys. Earth Planet. Int. 61, 141–148.
Marcus, S.L., Ghil, M. and Dickey, J.O.: 1994, The extratropical 40-day oscillation in the UCLA general circulation model. Part I: atmospheric angular momentum, J. Atmos. Sci. 51(11), 1431–1446.
Marquardt, D.: 1963, An algorithm for least-squares estimation of non-linear parameters, J. Soc. Indust. Appl. Math. 11(2), 431–441.
Masters, T.G. and Shearer, P.M.: 1990, Summary of the seismological constraints on the structure of the Earth's core, J. Geophys. Res. 95(21), 691–695.
Mathews, P., Buffett, B., Herring, T. and Shapiro, I.: 1991a, Forced nutations of the Earth: Influence of inner core dynamics 1. Theory, J. Geophys. Res. 96(B5), 8219–8242.
Mathews, P., Buffett, B., Herring, T. and Shapiro, I.: 1991b, Forced nutations of the Earth: Influence of inner core dynamics 2. Numerical results and comparisons, J. Geophys. Res. 96(B5), 8243–8257.
Melchior, P.: 1983, The tides of the planet Earth, 2nd edn., Pergamon Press, Oxford.
Melchior, P.: 1995, A continuing discussion about the correlation of tidal gravity anomalies and heat flow densities, Phys. Earth Planet Int. 88, 223–256.
Melchior, P. and Georis, B.: 1968, Earth tides, precession-nutation and the secular retardation of Earth's rotation, Phys. Earth Planet. Int. 1, 267–287.
Melchior, P. and Ducarme, B.: 1986, Detection of inertial gravity oscillations in the Earth's core with a superconducting gravimeter at Brussels, Phys. Earth Planet. Int. 42, 129–134.
Melchior, P., Ducarme, B. and Francis, O.: 1996, The response of the Earth to tidal body forces described by second and third degree spherical harmonics as derived from a 12 year series of measurements with the superconducting gravimeter GWR/T3 in Brussels, Phys. Earth Planet. Int. 93, 223–238.
Merriam, J.B.: 1992a, An ephemeris for gravity tide predictions at the nanogal level, Geophys. J. Int. 108, 415–422.
Merriam, J.B.: 1992b, Atmospheric pressure and gravity, Geophys. J. Int. 109, 488–500.
Merriam, J.B.: 1994, The nearly diurnal free wobble resonance in gravity measured at Cantley, Quebec, Geophys. J. Int. 119, 369–380.
Merriam, J.B.: 1995, Non-linear tides observed with the superconducting gravimeter, Geophys. J. Int. 123, 529–540.
Morelli, A. and Dziewonski, A.M.: 1987, Topography of the core-mantle boundary and lateral homogeneity of the liquid core, Nature 325, 678–683.
Mukai, A., Higashi, T., Takemoto, S., Nakagawa, I. and Naito, I.: 1995, Accurate estimation of atmospheric effects on gravity observations made with a superconducting gravity meter at Kyoto, Phys. Earth Planet. Inter. 91, 149–159.
Mukai, A.: 1997, Effects of groundwater on gravity observation at Kyoto, in JAG Symposia vol. 117, Gravity, Geoid, and Marine Geodesy, Segawa et al., eds., Springer-Verlag Berlin, pp. 123–130.
Nawa, K., Suda, N., Fukao, Y., Sato, T., Aoyama, Y. and Shibuya, K.: 1998, Incessant excitation of the Earth's free oscillations, Earth Planets Space 50, 3–8.
Neuberg, J., Hinderer, J. and Zürn, W.: 1987, Stacking gravity tide observations in Central Europe for the retrieval of the complex eigenfrequency of the nearly diurnal free wobble, Geophys. J. Roy. astr. Soc. 91, 853–868.
Neuberg, J., Hinderer, J. and Zürn, W.: 1990, On the complex eigenfrequency of the nearly diurnal free wobble and its geophysical interpretation, in Variations in Earth Rotation, Geophys. Monograph Series, AGU, 59, 11–16.
Neumeyer, J. and Dittfeld, H.-J.: 1997, Results of three year observation with a superconducting gravimeter at the GeoForschungsZentrum Potsdam, J. Geodesy 71, 97–102.
Niebauer, T., Sasagawa, G., Faller, J., Hilt, R. and Klopping, F.: 1995, A new generation of absolute gravimeters, Metrologia 32(3), 159–180.
Peter, G., Klopping, F. and Berstis, K.A.: 1995, Observing and modeling gravity changes caused by soil moisture and groundwater table variations with superconducting gravimeters in Richmond, Florida, USA, in Proc. ECGSWorkshop on ‘Non-tidal gravity changes: intercomparison between absolute and superconducting gravimeters’, Cahiers du Centre Européen de Géodynamique et de Seismologie, Walferdange, Luxemburg, 11, 147–159.
Peterson, J.: 1993, Observations and modeling of seismic background, U.S. Geological Survey Report, pp. 93–322.
Pillet, R., Florsch, N., Hinderer, J. and Rouland, D.: 1994, Performance of Wielandt-Streckeisen STS-1 seismometers in the tidal domain-preliminary results, Phys. Earth Planet. Inter. 84, 161–178.
Platzman, G.W., Curtis, G.A., Hansen, K.S. and Slater, R.D.: 1981, Normal modes of the world ocean: II. Description of modes in the period range 8-80 hr, J. Phys. Oceanogr. 12, 549–669.
Prothero, W.A. and Goodkind, J.: 1968, A superconducting gravimeter, Rev. Sci. Instr. 39(9), 1257–1268.
Prothero, W.A. and Goodkind, J.: 1972, Earth-tide measurements with the superconducting gravimeter, J. Geophys. Res. 77, 926–932.
Richter, B.: 1990, The long period elastic behaviour of the earth, in D.D. McCarthy and W.E. Carter, eds., Variations of Earth Rotation, Geophys. Monograph, IUGG, 9, 21–25.
Richter, B.: 1995, Cryogenic gravimeters: status report on calibration, data acquisition and environmental effects, in Proc. ECGS Workshop on ‘Non-tidal gravity changes: intercomparison between absolute and superconducting gravimeters’, Cahiers du Centre Européen de Géodynamique et de Seismologie, Walferdange, Luxemburg, 11, 125–146.
Richter, B. and Zürn, W.: 1988, Chandler effects and the nearly diurnal free wobble as determined from observations with a superconducting gravimeter, in Babcock, A. and Wilkins, G., eds., The Earth's rotation and reference frames for Geodesy and Geodynamics, Kluwer, Dordrecht, pp. 309–315.
Richter, B., Wilmes, H. and Nowak, I.: 1995a, The Frankfurt calibration system for relative gravimeters, Metrologia 32, 217–223.
Richter, B., Wenzel, H.G., Zürn, W. and Klopping, F.: 1995b, From Chandler wobble to free oscillations: comparison of cryogenic gravimeters and other instruments in a wide period range, Phys. Earth Planet. Inter. 91, 131–148.
Rieutord, M.: 1991, Linear theory of rotating fluids using spherical harmonics part II, Time-periodic flows, Geophys. Astrophys. Fluid Dyn. 59, 185–208.
Rochester, M. and Peng, Z.: 1993, The Slichter modes of a rotating Earth: a test of the subseismic approximation, Geophys. J. Int. 113, 575–585.
Roosbeek, F.: 1996, RATGP95: a harmonic development of the tide-generating potential using an analytical method, Geophys. J. Int. 126, 197–204.
Rydelek, P. and Knopoff, L.: 1984, Spectral analysis of gapped data: search for the mode 1S1 at the South Pole, J. Geophys. Res. 89, 1899–1902.
Rydelek, P., Knopoff, L. and Zürn, W.: 1982, Observation of 18.6-year modulation tide at the South pole, J. Geophys. Res. 87(B7), 5535–5537.
Rydelek, P., Zürn, W. and Hinderer, J.: 1991, On tidal gravity, heat flow and lateral heterogeneities, Phys. Earth Planet. Inter. 68, 215–229.
Sasao, T., Okubo, S. and Saito, M.: 1980, A simple theory on dynamical motion of a stratified fluid core upon nutational motion of the Earth, in Fedorov, E.P., Smith, M.L. and Bender, P.L., eds., Proc. IAU Symp. 78, Nutations and the Earth's Rotation, Reidel, Dordrecht, pp. 165–183.
Sato, T., Tamura, Y., Higashi, T., Takemoto, I., Nakagawa, I., Morimoto, N., Fukuda, Y., Segawa, J. and Seama, N.: 1994, Resonance parameters of nearly diurnal free core nutation measured with three superconducting gravimeters in Japan, J. Geomag. Geoelectr. 46, 571–586.
Sato, T., Ooe, M., Nawa, K., Shibuya, K., Tamura, Y. and Kaminuma, K.: 1997a, Long-period tides observed with a superconducting gravimeter at Syowa station, Antartica, and their implication to global ocean tide modeling, Phys. Earth Planet. Int. 103, 39–53.
Sato, T., Nawa, K., Shibuya, K., Tamura, Y., Ooe, M., Kaminuma, K. and Aoyama, Y.: 1997b, Polar motion effect on gravity observed with a superconducting gravimeter at Syowa station, Antarctica, in Segawa et al., eds., IAG Symposia vol. 117, Gravity, Geoid, and Marine Geodesy, Springer-Verlag, Berlin, pp. 99–106.
Schwahn, W.: 1998, Parameters for Sa and polar motion from gravimetric time series in Central Europe-a review, in B. Ducarme and P. Pâquet, eds., Proc. 13th Int. Symp. Earth Tides, Brussels, pp. 357–364.
Schwiderski, E.: 1980, On charting global ocean tides, Rev. Geophys. Space Phys. 18, 243–268.
Slichter, L.B.: 1961, The fundamental free mode of the Earth's inner core, Proc. Nat. Acad. Sci., USA 47, 186–190.
Smylie, D.E.: 1992, The inner core translational triplet and the density near Earth's center, Science 255, 1678–1682.
Smylie, D. and Rochester, M.: 1981, Compressibility, core dynamics and the subseismic wave equation, Phys. Earth Planet. Int. 24, 308–319.
Smylie, D.E., Jiang, X., Brennan B.J. and Sato, K.: 1992, Numerical calculation of modes of oscillation of the Earth's core, Geophys. J. Int. 108, 465–490.
Smylie, D.E., Hinderer, J., Richter, B. and Ducarme, B.: 1994, The product spectra of gravity and barometric pressure in Europe, Phys. Earth Planet. Inter. 80, 135–157.
Suda, N. and Fukao, Y.: 1990, Structure of the inner core inferred from observations of seismic core modes, Geophys. J. Int. 103, 403–413.
Suda, N., Nawa, K. and Fukao, Y.: 1998, Earth's background free oscillations, Science 279, 2089–2091.
Tanimoto, T., Um, J., Nishida, K. and Kobayashi, N.: 1998, Earth's continuous oscillations observed on seismically quiet days, Geophys. Res. Lett. 25, 1553–1556.
Tamura, Y.: 1987, An harmonic development of the tide generating potential, Bull. Inf. Marées Terrestres 99, 6813–6855.
Tarantola, A. and Valette, B.: 1982, Generalized nonlinear inverse problems solved using the least squares criterion, Rev. Geophys. Space Phys. 20(2), 219–232.
Toomre, A.: 1974, On the nearly diurnal free wobble of the Earth, Geophys J. R. astr. Soc. 38, 335–348.
Van Camp, M.: 1999, Measuring seismic normal modes with the GWR C021 superconducting gravimeter. Phys. Earth Planet. Inter. 116, 81–92.
Van Camp, M., Wenzel, H.-G., Schott, P., Vauterin, P. and Francis, O.: 2000, Accurate transfer function determination for superconducting gravimeters, Geophys. Res. Lett. 27(1), 37–40.
van Dam, T. and Francis, O.: 1998, Two years of continuous measurements of tidal and nontidal variations in gravity in Boulder, Colorado, Geophys. Res. Lett. 25(3), 393–396.
Varga, P, Hajosy, A. and Csapo, G.: 1995, Laboratory calibration of LaCoste-Romberg type gravimeters by using a heavy cylindrical ring, Geophys. J. Int. 120, 745–747.
Volland, H.: 1988, Atmospheric tidal and planetary waves. Kluwer Academic Publ., Dordrecht, 348 p.
Wahr, J.: 1981, Body tides of an elliptical, rotating, elastic and oceanless Earth, Geophys. J. R. astr. Soc. 64, 677–704.
Wahr, J.: 1985, Deformation induced by polar motion, J. Geophys. Res. 90(B11), 9363–9368.
Wahr, J. and Bergen, Z.: 1986, The effects of mantle anelasticity on nutations, earth tides, and tidal variations in rotation rate, Geophys. J. astr. Soc. 87, 633–668.
Wahr, J. and De Vries, D.: 1989, The possibility of lateral structure inside the core and its implications for certain geodetic observations, Geophys. J. 99, 511–519.
Wang, R.: 1994, Effect of rotation and ellipticity on Earth tides, Geophys. J. Int. 117, 562–565.
Warburton, R.J. and Goodkind, J.M.: 1977, Detailed gravity-tide spectrum between one and four cycles per day, Geophys. J. 52, 117–136.
Warburton, R.J. and Goodkind, J.M.: 1978, The influence of barometric pressure variations on gravity, Geophys. J. 48, 281–292.
Warburton, R.J. and Brinton, E.: 1995, Recent developments in GWR Instruments superconducting gravimeters, in Proc. ECGS Workshop on ‘Non-tidal gravity changes: intercomparison between absolute and superconducting gravimeters’, Cahiers du Centre Européen de Géodynamique et de Séismologie, Walferdange, Luxemburg, 11, 23–56.
Wenzel, H.G.: 1995, Accurate instrumental phase lag determination for feedback gravimeters, in H.T. Hsu ed., Proc. 12th Int. Symp. Earth Tides, Sciences Press, Beijing-New York, pp. 191–198.
Wielandt, E. and Streckeisen, G.: 1982, The leaf-spring seismometer: design and performances, Bull. Seism. Soc. Am. 66, 987–996.
Wielandt, E. and Steim, J.: 1986, A digital very broadband seismograph, Ann. Geophys., 4B, 227.
Wu, W.-J. and Rochester, M.: 1994, Gravity and Slichter modes of the rotating Earth, Phys. Earth Planet. Int. 87, 137–154.
Xi Qinwen: 1987, A new complete development of the tide generating potential for the epoch J 2000.0, Bull. Inf. Marées Terrestres 99, 6786–6812.
Xi Qinwen: 1989, The precision of the development of the tidal generating potential and some explanatory notes, Bull. Inf. Marées Terrestres 105, 7396–7404.
Zürn, W., Rydelek, P. and Richter, B.: 1986, The core-resonance in the record of the superconducting gravimeter at Bad Homburg, in R. Viera, ed., Proc. 10th Int. Symp. Earth Tides, Cons. Sup. Invest. Cient., Madrid, pp. 141–147.
Zürn, W., Richter, B., Rydelek, P. and Neuberg, J.: 1987, Comments on detection of inertial gravity oscillations in the Earth's core with a superconducting gravimeter at Brussels, Phys. Earth Planet. Int. 49, 176–178.
Zürn, W., Wenzel, H.G. and Laske, G.: 1991, High quality data from LaCoste-Romberg gravimeters with electrostatic feedback: a challenge for superconducting gravimeters, Bull. Inf.Mar' ees Terr. 110, 7940–7952.
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Hinderer, J., Crossley, D. Time Variations In Gravity And Inferences On The Earth's Structure And Dynamics. Surveys in Geophysics 21, 1–45 (2000). https://doi.org/10.1023/A:1006782528443
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DOI: https://doi.org/10.1023/A:1006782528443