Abstract
The superconducting gravimeter (SG) can provide excellent data to infer Earth’s surface time-varying gravity signals. In this study, we analyze the measurements and experiments of the newly established iGrav-007 SG during 2013–2019. The SG calibration factors with relative precisions of 0.0923% and 0.0782% are determined from two parallel registrations with FG5 absolute gravimeters, and the SG sensitivity calibration to the 0.1 μGal level is presented from a moving external-mass experiment. The local synthesized tides are then calculated with ET34-ANA-V73 software, and nine different ocean tide models for the eight diurnal/semi-diurnal constituents are tested for corrections of the ocean tide gravity effects. After preprocessing the raw SG data, we compare the gravity residuals with colocated precipitation, groundwater level, and GPS height observations from June 2017 to December 2018. Meanwhile, the local precipitation gravity effects are modeled by considering the recharge and discharge time, and the groundwater variation influences are described using a regression model with an admittance coefficient of 0.65 μGal/m. We are able to show good correlations between the gravity residuals and height changes as well as the estimated local and global water storage loading effects in the annual and seasonal (about 140 days) terms.
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Acknowledgements
We acknowledge M.S. Bos and H.-G. Scherneck for making the possible access to the free Ocean Tide Loading Provider (http://holt.oso.chalmers.se/loading/index.html). The atmospheric, non-tidal oceanic, and hydrological loading models are provided by the ESMGFZ product reposity (http://rz-vm115.gfz-potsdam.de:8080/repository). We thank the reviewers (D. Crossley and an anonymous reviewer) and the associate editor U. Riccardi for their very valuable comments and suggestions, all of which greatly improved the manuscript.
Funding
This study is supported by the National Natural Science Foundation of China (Grant Nos. 41874032, 42030105, 41631072, 41721003).
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Appendix
Appendix
Adjusted tidal parameters for Kumming (iGrav-007 sensor), from June 2017 to September 2019.
fmin (cpd) | fmax (cpd) | Wave | Ath (nm/s2) | δ | δ error | κ (°) | κ error (°) |
|---|---|---|---|---|---|---|---|
0.580000 | 0.791600 | SGM2Q1 | 0.29210 | 1.12911 | 0.59462 | 35.669 | 30.149 |
0.791601 | 0.810000 | 2SGM1 | 0.18122 | 0.53153 | 0.98048 | 81.597 | 105.630 |
0.810001 | 0.821300 | 3Q1 | 0.68057 | 1.31718 | 0.27191 | − 4.546 | 11.834 |
0.821301 | 0.842147 | SGMQ1 | 1.76311 | 1.17703 | 0.10148 | − 3.665 | 4.940 |
0.842148 | 0.860500 | 2Q1 | 6.05140 | 1.14530 | 0.03055 | 2.438 | 1.529 |
0.860501 | 0.878675 | SGM1 | 7.29747 | 1.18998 | 0.02507 | − 1.113 | 1.208 |
0.878676 | 0.896800 | Q1 | 45.72919 | 1.16396 | 0.00808 | − 0.452 | 0.398 |
0.896801 | 0.915000 | RO1 | 8.67999 | 1.18510 | 0.02065 | − 1.940 | 0.998 |
0.915001 | 0.933200 | O1 | 238.83795 | 1.15839 | 0.00185 | − 0.639 | 0.091 |
0.933201 | 0.947991 | TAU1 | 3.11325 | 1.23643 | 0.04684 | 3.307 | 2.171 |
0.947992 | 0.964460 | NTAU1 | 1.76125 | 1.30543 | 0.10628 | 3.494 | 4.665 |
0.964461 | 0.966853 | NO1 | 18.77436 | 1.12208 | 0.01045 | 0.085 | 0.534 |
0.966854 | 0.971667 | CHI1 | 3.59250 | 1.18039 | 0.05047 | 0.306 | 2.449 |
0.971668 | 0.996933 | PI1 | 6.49225 | 1.14241 | 0.02586 | 3.732 | 1.297 |
0.996934 | 0.998631 | P1 | 111.11307 | 1.15033 | 0.00151 | − 0.361 | 0.075 |
0.998632 | 1.002333 | S1 | 2.62542 | 2.39401 | 0.08979 | − 42.777 | 2.150 |
1.002334 | 1.004200 | K1 | 335.76870 | 1.12729 | 0.00088 | − 0.728 | 0.045 |
1.004201 | 1.006845 | PSI1 | 2.62664 | 1.13146 | 0.06429 | − 6.466 | 3.256 |
1.006846 | 1.023622 | PHI1 | 4.78026 | 1.18537 | 0.03502 | − 2.703 | 1.693 |
1.023623 | 1.035379 | TET1 | 3.59147 | 1.22358 | 0.05020 | 0.808 | 2.351 |
1.035380 | 1.055000 | J1 | 18.78093 | 1.15292 | 0.00963 | − 0.669 | 0.478 |
1.055001 | 1.075633 | SO1 | 3.11470 | 1.13650 | 0.05640 | − 0.610 | 2.844 |
1.075634 | 1.086000 | OO1 | 10.27093 | 1.14758 | 0.02336 | − 0.051 | 1.166 |
1.086001 | 1.112600 | NU1 | 1.96688 | 1.00750 | 0.11462 | 0.351 | 6.518 |
1.112601 | 1.470243 | 2(KM)P | 0.31408 | 1.13603 | 0.55572 | 3.169 | 28.041 |
1.470244 | 1.808000 | 2EPS2 | 0.75169 | 1.25113 | 0.07930 | − 8.952 | 3.632 |
1.808001 | 1.824458 | 3N2 | 1.75415 | 1.13590 | 0.04078 | − 0.567 | 2.058 |
1.824459 | 1.845944 | EPS2 | 4.54675 | 1.15721 | 0.01649 | 0.649 | 0.816 |
1.845945 | 1.863026 | 2N2 | 15.59133 | 1.16725 | 0.00479 | − 0.854 | 0.235 |
1.863027 | 1.880264 | MUE2 | 18.81743 | 1.16862 | 0.00423 | − 0.293 | 0.207 |
1.880265 | 1.899500 | N2 | 117.82104 | 1.16217 | 0.00155 | − 0.315 | 0.076 |
1.899501 | 1.915114 | NUE2 | 22.38086 | 1.16709 | 0.00360 | − 0.073 | 0.177 |
1.915115 | 1.928402 | GAM2 | 1.84740 | 1.16129 | 0.04058 | 0.599 | 2.002 |
1.928403 | 1.930667 | ALF2 | 2.11363 | 1.20579 | 0.03723 | − 1.964 | 1.769 |
1.930668 | 1.933790 | M2 | 615.36173 | 1.16063 | 0.00020 | − 0.323 | 0.010 |
1.933791 | 1.936152 | BET2 | 1.86198 | 1.24436 | 0.04382 | − 3.485 | 2.018 |
1.936153 | 1.950419 | DEL2 | 0.72135 | 1.30616 | 0.08591 | − 1.024 | 3.770 |
1.950420 | 1.964767 | LAM2 | 4.53766 | 1.13366 | 0.01773 | 0.152 | 0.896 |
1.964768 | 1.984282 | L2 | 17.39501 | 1.16273 | 0.00547 | − 1.012 | 0.269 |
1.984283 | 1.995500 | 2T2 | 0.67854 | 0.81121 | 0.12176 | − 5.557 | 8.603 |
1.995501 | 1.998996 | T2 | 16.72639 | 1.14759 | 0.00497 | 0.685 | 0.248 |
1.998997 | 2.001678 | S2 | 286.27319 | 1.15911 | 0.00029 | − 0.117 | 0.014 |
2.001679 | 2.004380 | R2 | 2.38853 | 1.21276 | 0.02802 | − 5.506 | 1.324 |
2.004381 | 2.010635 | K2 | 77.77178 | 1.15542 | 0.00124 | − 0.316 | 0.062 |
2.010636 | 2.022488 | KPHI2 | 0.52974 | 0.83991 | 0.15448 | − 1.263 | 10.538 |
2.022489 | 2.038400 | ZETA2 | 0.83174 | 1.39470 | 0.13359 | − 0.479 | 5.489 |
2.038401 | 2.056000 | ETA2 | 4.35033 | 1.19596 | 0.02123 | 0.403 | 1.017 |
2.056001 | 2.075800 | 2S2 | 0.72150 | 1.19121 | 0.14445 | − 7.991 | 6.949 |
2.075801 | 2.092667 | 2K2 | 1.13800 | 1.28363 | 0.12152 | 6.197 | 5.426 |
2.092668 | 2.396000 | 2KN2 | 0.21796 | 0.77336 | 0.48262 | − 21.652 | 35.768 |
2.580000 | 2.826600 | M2N3 | 0.51990 | 1.15411 | 0.11447 | − 7.906 | 5.684 |
2.826601 | 2.850000 | MMUE3 | 0.52263 | 1.16052 | 0.12748 | 5.295 | 6.294 |
2.850001 | 2.864300 | MN3 | 2.99898 | 1.04050 | 0.02177 | − 1.314 | 1.198 |
2.864301 | 2.880000 | MNUE3 | 0.56142 | 1.01662 | 0.11942 | 4.036 | 6.729 |
2.880001 | 2.915496 | M3 | 10.94282 | 1.05897 | 0.00617 | − 0.375 | 0.334 |
2.915497 | 2.953157 | ML3 | 0.61974 | 1.11906 | 0.10535 | 2.054 | 5.393 |
2.953158 | 3.340000 | MK3 | 1.42524 | 1.13764 | 0.05860 | 5.933 | 2.951 |
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Luan, W., Shen, W. & Jia, J. Analysis of iGrav Superconducting Gravity Measurements in Kunming, China, with Emphasis on Calibration, Tides, and Hydrology. Pure Appl. Geophys. 180, 643–660 (2023). https://doi.org/10.1007/s00024-022-03036-6
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DOI: https://doi.org/10.1007/s00024-022-03036-6