Abstract
The long-term continuous gravity observations obtained by the superconducting gravimeters (SG) at seven globally-distributed stations are comprehensively analyzed. After removing the signals related to the Earth’s tides and variations in the Earth’s rotation, the gravity residuals are used to describe the seasonal fluctuations in gravity field. Meanwhile, the gravity changes due to the air pressure loading are theoretically modeled from the measurements of the local air pressure, and those due to land water and nontidal ocean loading are also calculated according to the corresponding numerical models. The numerical results show that the gravity changes due to both the air pressure and land water loading are as large as 100×10−9 m s−2 in magnitude, and about 10×10−9 m s−2 for those due to the nontidal ocean loading in the coastal area. On the other hand, the monthly-averaged gravity variations over the area surrounding the stations are derived from the spherical harmonic coefficients of the GRACE-recovered gravity fields, by using Gaussian smoothing technique in which the radius is set to be 600 km. Compared the land water induced gravity variations, the SG observations after removal of tides, polar motion effects, air pressure and nontidal ocean loading effects and the GRACE-derived gravity variations with each other, it is inferred that both the ground- and space-based gravity observations can effectively detect the seasonal gravity variations with a magnitude of 100×10−9 m s−2 induced by the land water loading. This implies that high precision gravimetry is an effective technique to validate the reliabilities of the hydrological models.
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Zhang F P, Dong D N, Cheng Z Y, et al. Crustal vertical seasonal variations in China observed by GPS (in Chinese). Chin Sci Bull, 2002, 47(18): 1370–1377
Zhang S Y, Zhong M, Yan H M, et al. Meteorological excitation on annual variation of vertical displacement at Chinese GPS fundamental stations (in Chinese). Sci Surv Map, 2004, 29(2): 34–36
Chen J L, Wilson C R, Tapley B D. Interannual variability of low degree gravitational change, 1980–2002. J Geod, 2005, Doi: 10.1007/s00190-004-0417-y
Milly P C D, Shmakin A B. Global modeling of land water and energy balances. Part I: The land dynamics (LaD) model. J Hydromet, 2002, 3(3): 283–299
Rodell M, Houser P R, Jambor U, et al. The global land data assimilation system. Bull Am met Soc, 2004, 85: 381–394
Tapley B, Ries J, Bettadpur S, et al. GGM02-An improved Earth gravity field model from GRACE. J Geod, 2005, 79(8): 467–478
Zhou X H, Hsu H, Wu B, et al. Earth’s gravity field derived from GRACE satellite tracking data (in Chinese). Chin J Geophys, 2006, 49(3): 718–723
Ramillien G, Cazenave A, Brunau O. Global time variations of hydrological signals from GRACE Satellite gravimetry. Geophys J Int, 2004, 158: 813–826
Jekeli C. Alternative methods to smooth the Earth’s gravity field. Rep. 327, Dep Geod Sci and Surv, Ohio State Univ, Columbus, 1981
Crossley D, Hinderer J, Llubes M, et al. The potential of ground gravity measurements to validate GRACE data. Adv Geosci, 2005, 1: 1–7
Rosat S, Hinderer J, Crossley D, et al. The search for the Slichter mode: comparison of noise levels of superconducting gravimeters and investigation of a stacking method. Phys Earth Planet Inter, 2003, 140: 183–202
Sun H P, Xu H Z. Execution and prospect for the global geodynamics project cooperation (in Chinese). Adv Earth Sci, 1997, 12(2): 152–157
Crossley D, Hinderer J, Casula G, et al. Network of superconducting gravimeters benefits a number of disciplines. EOS, 1999, 80(11): 121125–121126
Boy J P, Hinderer J. Study of the seasonal gravity signal in superconducting gravimeter data. J Geodyn, 2006, 41: 227–233
Sato T, Boy J P, Tamura Y, et al. Gravity tide and seasonal gravity variation at Ny-Ålesund, Svalbard in Arctic. J Geodyn, 2006, 41: 234–241
Neumeyer J, Barthelmes F, Dierks O, et al. Combination of temporal gravity variations resulting from superconducting gravimeter (SG) recordings, GRACE satellite observations and global hydrology models. J Geod, 2006, 79: 573–585
Van Camp M, Vauterin P. Tsoft: graphical and interactive software for the analysis of time series and Earth tides. Comput Geosci, 2005, 31(5): 631–640
Chen X D, Sun H P. Comparison and investigation of the analysis techniques for tidal gravity observations. In: Zhu Y Z, Sun H P, eds. Progress in Geodesy and Geodynamics (in Chinese). Wuhan: Hubei Science & Technology Press, 2004. 364–370
Wenzel H G. The nanogal software: data processing package ETERNA 3.3. Bull Inf Mar’ees Terrestres, 1996, 124: 9425–9439
Wahr J M. Deformation induced by polar motion. J Geophys Res, 1985, 90(B11): 9363–9368
Xu J Q, Sun H P, Yang X F. A study of gravity variations caused by polar motion using superconducting gravimeter data from the GGP network. J Geod, 2004, 78(3): 201–209
Yang X F, Sun H P, Xu J Q. Detection of gravitational effect of polar motion by use of auto-regression model (in Chinese). J Geod Geodyn, 2004, 24(2): 109–114
Ducarme B, Venedikov A P, Arnoso J, et al. Global analysis of the GGP superconducting gravimeters network for the estimation of the pole tide gravimetric amplitude factor. J Geodyn, 2006, 41: 334–344
Boy J P, Gegout P, Hinderer J. Reduction of surface gravity data from global atmospheric pressure loading. Geophys J Int, 2002, 149: 534–545
Farrell W E. Deformation of the Earth by surface loads. Rev Geophys Space Phys, 1972, 10: 761–797
Whar J, Molenaar M, Bryan F. Time variability of the earth’s gravity field: Hydrological and oceanic effects and their possible detection using GRACE. J Geophys Res, 1998, 103(B12): 30205–30229
Flechter F. GFZ level-2 processing standards document. GRACE 327-743, http://isdc.gfz-potsdam.de
Xu J Q, Zhou J C, Luo S C, et al. Study on characteristics of long-term gravity changes at Wuhan station. Chin Sci Bull, 2008, 53(13): 2033–2040
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Supported by Knowledge Innovation of Chinese Academy of Sciences (Grant No. KZCX2-YW-133), National Natural Science Foundation of China (Grant Nos. 40730316 and 40574034) and Frontier Domain Item of Chinese Academy of Sciences
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Zhou, J., Sun, H. & Xu, J. Validating global hydrological models by ground and space gravimetry. Chin. Sci. Bull. 54, 1534–1542 (2009). https://doi.org/10.1007/s11434-009-0006-9
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DOI: https://doi.org/10.1007/s11434-009-0006-9