An internally damped inertial platform for marine gravimetry and a test case in the South China Sea -- Journal of Oceanology and Limnology,2023,41(2):816-829

	Cite this paper:
	Pengfei WU, Lin WU, Lifeng BAO, Long WANG, Bo WANG, Danling TANG. An internally damped inertial platform for marine gravimetry and a test case in the South China Sea[J]. Journal of Oceanology and Limnology, 2023, 41(2): 816-829

An internally damped inertial platform for marine gravimetry and a test case in the South China Sea

Pengfei WU¹, Lin WU¹, Lifeng BAO^1,2, Long WANG¹, Bo WANG^1,4, Danling TANG³

1 State Key Laboratory of Geodesy and Earth's Dynamics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430077, China;
2 University of Chinese Academy of Sciences, Beijing 100049, China;
3 Guangdong Remote Sensing Center for Marine Ecology and Environment(GDRS), Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou), Guangzhou 511458, China;
4 School of Geography and Information Engineering, China University of Geosciences, Wuhan 430074, China

Abstract:

To dampen periodic off-levelling motions within an inertial platform while undergoing horizontal accelerations of the same period and to achieve a levelling accuracy of a few tens of arcseconds with that system, an internally damped inertial platform for a marine scalar gravity system was the developed. Methods for attenuating horizontal acceleration and reducing off-levelling error by a satisfactory gyro-levelling loop, which are fundamental to the internally damped inertial platform, were designed and implemented. In addition, phase delays are introduced by the levelling loop. The resulting off-levelling gravity errors were analyzed and modeled. A series of tests on a motion simulator were performed in laboratory for a variety of simulated sea conditions. We found that the motion of the platform is a function of the amplitude and period of the simulated ship motions and ranges between 10 and 40 arcseconds. In addition, the phase lag between platform motion and ship motion is not constant but ranges 180°-270°, depending on the period and amplitude of the motion. Then, the platform, on which a gravimeter was mounted, was installed on the R/V Shiyan 2 to conduct a gravity survey in the South China Sea. Despite rough sea conditions, it was shown that in short periods of 2-30 s, the off-levelling angle was less than 30 arcseconds, and the phase lagged the horizontal acceleration by 230°-260°. From a repeated survey line and intersecting survey points, the estimated errors of gravity measurements were between 1.3 and 1.7 mGal. The marine measurements results were compared with those of satellite altimetry data and show a mean value of 0.5 mGal in a standard deviation of 1.5 mGal.

Key words: internally damped platform|gyro-levelling loop|marine gravimetry

Received: 2022-10-07 Revised:

Tools

PDF (5213 KB) Free

Print this page

Add to favorites

Email this article to others

Authors

Articles by Pengfei WU

Articles by Lin WU

Articles by Lifeng BAO

Articles by Long WANG

Articles by Bo WANG

Articles by Danling TANG

References:
[1] Abbasi M, Barriot J P, Verdun J. 2007. Airborne LaCoste & Romberg gravimetry:a space domain approach. Journal of Geodesy, 81(4):269-283, https://doi.org/10.1007/s00190-006-0107-z.
[2] Abramov D V, Koneshov V N. 2015. On the characteristics and potential facilities of the sensitive unit of the GT-2A gravimeter. Seismic Instruments, 51(1):80-84, https://doi.org/10.3103/S0747923915010028.
[3] Ander M E, Summers T, Gruchalla M E. 1999. LaCoste & Romberg gravity meter:system analysis and instrumental errors. Geophysics, 64(6):1708-1719, https://doi.org/10.1190/1.1444675.
[4] Andersen O B, Knudsen P. 2019. The DTU17 global marine gravity field:first validation results. In:Mertikas S, Pail R eds. Fiducial Reference Measurements for Altimetry.Springer, Cham. p.83-87, https://doi.org/10.1007/1345_2019_65.
[5] Argyle M, Ferguson S, Sander L et al. 2000. AIRGrav results:a comparison of airborne gravity data with GSC test site data. The Leading Edge, 19(10):1134-1138, https://doi.org/10.1190/1.1438494.
[6] Bruton A M, Hammada Y, Ferguson S et al. 2001. A comparison of inertial platform, damped 2-axis platform and strapdown airborne gravimetry. In:Proceedings of the International Symposium on Kinematic Systems in Geodesy, Geomatics and Navigation. Banff, Canada. p.542-550.
[7] Cai S K, Tie J, Zhang K D et al. 2017. Marine gravimetry using the strapdown gravimeter SGA-WZ. Marine Geophysical Research, 38(4):325-340, https://doi.org/10.1007/s11001-017-9312-9.
[8] Forsberg R, Olesen A V, Einarsson I. 2015. Airborne gravimetry for geoid determination with Lacoste Romberg and Chekan gravimeters. Gyroscopy and Navigation, 6(4):265-270, https://doi.org/10.1134/S2075108715040069.
[9] Glennie C L, Schwarz K P, Bruton A M et al. 2000. A comparison of stable platform and strapdown airborne gravity. Journal of Geodesy, 74(5):383-389, https://doi.org/10.1007/s001900000082.
[10] Golovan A A, Klevtsov V V, Koneshov I V et al. 2018. Application of GT-2A gravimetric complex in the problems of airborne gravimetry. Izvestiya, Physics of the Solid Earth, 54(4):658-664, https://doi.org/10.1134/S1069351318040043.
[11] Lequentrec-Lalancette M F, Salaün C, Bonvalot S et al. 2016. Exploitation of marine gravity measurements of the mediterranean in the validation of global gravity field models. In:International Symposium on Earth and Environmental Sciences for Future Generations. Springer, Prague, Czech Republic. p.63-67, https://doi.org/10.1007/1345_2016_258.
[12] Li Q Q, Bao L F, Wang Y. 2021. Accuracy evaluation of altimeter-derived gravity field models in offshore and coastal regions of China. Frontiers in Earth Science, 9:722019, https://doi.org/10.3389/feart.2021.722019.
[13] Sander S, Elieff S H P, Sander L. 2015. Accuracy of SGL's AIRGrav airborne gravity system from the Kauring test site and results from a regional hydrocarbon exploration survey. In:International Workshop and Gravity, Electrical & Magnetic Methods and their Applications.
[14] Society of Exploration Geophysicists and Chinese Geophysical Society, Chenghu, China. p. 29-32, https://doi.org/10.1190/GEM2015-008.
[15] Sandwell D T, Müller R D, Smith W H F et al. 2014. New global marine gravity model from CryoSat-2 and Jason-1 reveals buried tectonic structure. Science, 346(6205):65-67, https://doi.org/10.1126/science.1258213.
[16] Schwarz K P, Wei M. 1995. Some unsolved problems in airborne gravimetry. In Gravity and Geoid:Joint Symposium of the International Gravity Commission and the International Geoid Commission (p.131-150).Springer Berlin Heidelberg, https://doi.org/10.1007/978-3-642-79721-7_15.
[17] Shinohara M, Yamada T, Ishihara T et al. 2015. Development of an underwater gravity measurement system using autonomous underwater vehicle for exploration of seafloor deposits. In:OCEANS 2015-Genova. IEEE, Genova, Italy. p.1-7, https://doi.org/10.1109/OCEANS-Genova.2015.7271487.
[18] Shinohara M, Yamada T, Kanazawa T et al. 2013. Development of an underwater gravimeter and the first observation by using autonomous underwater vehicle. In:2013 IEEE International Underwater Technology Symposium (UT). IEEE, Tokyo, Japan. p.1-6, https://doi.org/10.1109/UT.2013.6519864.
[19] Smoller Y L, Yurist S S, Golovan A A et al. 2015. Using a multiantenna GPS receiver in the airborne gravimeter GT-2a for surveys in polar areas. Gyroscopy and Navigation, 6(4):299-304, https://doi.org/10.1134/S2075108715040100.
[20] Stelkens-Kobsch T H. 2006. Further development of a high precision two-frame inertial navigation system for application in airborne gravimetry. In:Flury J, Rummel R, Reigber C et al eds. Observation of the Earth System from Space. Springer, Berlin, Heidelberg. p.479-494, https://doi.org/10.1007/3-540-29522-4_31.
[21] Studinger M, Bell R, Frearson N. 2008. Comparison of AIRGrav and GT-1A airborne gravimeters for research applications. Geophysics, 73(6):I51-I61, https://doi.org/10.1190/1.2969664.
[22] Tang D L, Liu W, Sui G J et al. 2021. A bibliometric analysis of remote sensing research hotspots on the South China Sea and its U-boundary. Journal of Tropical Oceanography, 40(3):83-95, https://doi.org/10.11978/YG2020004. (in Chinese with English abstract)
[23] Tang D L, Liu Y P, Hao X G et al. 2018. A newly-discovered historical map using both national boundary and administrative line to represent the U-boundary in the South China Sea. Chinese Science Bulletin, 63(9):856-864, https://doi.org/10.1360/N972017-00440. (in Chinese with English abstract)
[24] Verdun J, Klingelé E E. 2005. Airborne gravimetry using a strapped-down LaCoste and Romberg air/sea gravity meter system:a feasibility study. Geophysical Prospecting, 53(1):91-101, https://doi.org/10.1111/j.1365-2478.2005.00436.x.
[25] Wang W, Gao J Y, Li D M et al. 2018. Measurements and accuracy evaluation of a strapdown marine gravimeter based on inertial navigation. Sensors, 18(11):3902, https://doi.org/10.3390/s18113902.
[26] Watts A B, Tozer B, Harper H et al. 2020. Evaluation of shipboard and satellite-derived bathymetry and gravity data over seamounts in the northwest Pacific Ocean. Journal of Geophysical Research:Solid Earth, 125(10):e2020JB020396, https://doi.org/10.1029/2020JB020396.
[27] Xiong Z M, Cao J L, Liao K X et al. 2020. A new method for underwater dynamic gravimetry based on multisensor integrated navigation. Geophysics, 85(3):G69-G80, https://doi.org/10.1190/geo2019-0006.1.
[28] Yuan Y, Gao J Y, Wu Z C et al. 2020. Performance estimate of some prototypes of inertial platform and strapdown marine gravimeters. Earth, Planets and Space, 72(1):89, https://doi.org/10.1186/s40623-020-01219-w.
[29] Zhang S J, Abulaitijiang A, Andersen O B et al. 2021. Comparison and evaluation of high-resolution marine gravity recovery via sea surface heights or sea surface slopes. Journal of Geodesy, 95(6):66, https://doi.org/10.1007/s00190-021-01506-8.