Influence of DEM grid spacing and correction radius on terrain correction in gravity exploration
ZHANG Fei-Fei1,2,3,4,5(), WANG Wan-Yin1,2,3,7,8(), LI Qian6, WANG Lin1,2,3, MA Jing1,2,3
1. Institute of Gravity and Magnetic Technology, Chang'an University, Xi'an 710054, China 2. School of Geology Engineering and Geomatics, Chang'an University, Xi'an 710054, China 3. Key Laboratory of Western China’s Mineral Resources and Geological Engineering Under Ministry of Education, Xi’an 710054, China 4. Key Laboratory of Gas Hydrate of Ministry of Natural Resources, Qingdao 266071, China 5. Qingdao Institute of Marine Geology, Qingdao 266071, China 6. Shanxi Provincial Institute of Geophysical and Geochemical Exploration, Yuncheng 044004, China 7. Key Laboratory of Marine Geology & Environment, CAS, Qingdao 266071, China 8. National Engineering Research Center of Offshore Oil and Gas Exploration, Beijing 100028, China
To remove the effect of terrain mass on observed gravity values, it is necessary to conduct terrain correction in gravity exploration. Terrains have the greatest impact on gravity values because they are the closest to observation points. However, the complex topographic relief makes it difficult to precisely determine the variation of topographic relief. Therefore, terrain correction is the most critical factor in the improvement of the precision of gravity exploration. The grid size of terrain data and the terrain correction radius are the key factors affecting the calculation precision of terrain correction. This study collected the DEM data with resolutions of 5 m, 10 m, 25 m, 50 m, and 100 m for plains, hills, and mountains. Based on these data, this study calculated conventional and generalized terrain correction values under different grid spacings and correction ranges and analyzed the influence of different grid spacings and correction radii on terrain correction in gravity exploration. The results are as follows: the gravity effect of the terrain mass above the geoid on the observation points was mainly concentrated in the range of 0~5 000 m and accounted for about 90% of the influence value of the total terrain mass. Attention should be paid to the correction of the middle and far areas during the terrain correction of hills and mountains, and it is necessary to appropriately increase the correction range of the middle areas; Different types of terrains had different requirements for grid spacings, and greater variations in topographic relief imposed higher requirements for the resolution DEM data. Based on the results of the comparative analysis, this study proposed some suggestions on the selection of DEM grid spacings and correction radii for different types of terrains. This study provides an important reference for the theoretical study and specification refinement of gravity terrain correction and has a great prospect for applications.
张菲菲, 王万银, 李倩, 王林, 马静. DEM网格间距及校正半径对重力地形校正的影响[J]. 物探与化探, 2023, 47(3): 597-607.
ZHANG Fei-Fei, WANG Wan-Yin, LI Qian, WANG Lin, MA Jing. Influence of DEM grid spacing and correction radius on terrain correction in gravity exploration. Geophysical and Geochemical Exploration, 2023, 47(3): 597-607.
Zhang J, Zhang B S, Di B Y, et al. The effect of grid spacing of elevation on the accuracy of median region terrain correction of gravity[J]. Geophysical and Geochemical Exploration, 2014, 38(1):157-161.
Huang M T, Zhai G J, Guan Z, et al. On computations of terrain correction and indirect effect using FFT[J]. Journal of Institute of Survering and Mapping, 2000, 17(4):242-246
Zhang G L, Zhao G X, Wang D Q, et al. A tentative discussion on the precision calculation method of median region terrain correction based on digital elevation model[J]. Geophysical and Geochemical Exploration, 2013, 37 37(6):1133-1140.
Feng Z H. The development of the gravity intermediate area topographic correction system[J]. Geophysical and Geochemical Exploration, 2002, 26(6):467-469.
Zhou X X, Li X. Gravity terrain corrections by surface integration method[J]. Computing Techniques for Geophysical and Geochemical Exploration, 1987, 9(4):273-279.
Hu M K, Jiang Y L, Li C, et al. Research and application on gravity terrain correction method based on surface integral[J]. Computing Techniques for Geophysical and Geochemical Exploration, 2015, 37(2):182-186.
[8]
Parker R L. The rapid calculation of potential anomalies[J]. Geophysics, 1973, 31(4):447-455.
[9]
Parker R L. Improved Fourier terrain correction[J]. Part Ⅰ.Geophysics, 1995, 60(4):1007-1017.
[10]
Parker R L. Improved Fourier terrain correction[J]. Part Ⅱ.Geophysics, 1996, 61(2):365-372.
Du J S, Chen C, Liang Q, et al. Gravity anomaly calculation based on volume integral in spherical cap and comparision with the Tesserio-Taylor series expansion approach[J]. Acta Geodaetica et Cartographica Sinca, 2012, 41(3):339-346.
An Y L, Zhang M H, Huang J M, et al. The computation scheme and computation process for gravity correction valus within the pure spherical coordinate system[J]. Geophysical and Geochemical Exploration, 2010, 34(6):697-705.
[13]
Schiavone D, Capolongo D, Loddo M. High resolution dems for near-station terrain correction in gravitymetry[R]. 2007 EGM International Workshop,2007.
Liu K H, Geng T, Yang H Y, et al. The gravimetry near-station terrain correction instrument system based on Laser distance- measurement technology[J]. Geophysical and Geochemical Exploration, 2012, 36(3):403-408.
Zhang X L. Application of UAV aerial survey technology in gravimetry terrain correction[J]. Technology and Market, 2021, 28(6):111-112.
[16]
Heck B, Seitz K. A comparison of the tesseroid,prism and point-mass approaches for mass reductions in gravity field modelling[J]. Journal of Geodesy, 2007, 81(2):121-136.
doi: 10.1007/s00190-006-0094-0
Li Z J, Zhou D R, Zhang Y, et al. Comparative study on several DEM-base Strategies for terrain reduction of gravity[J]. Hydrographic Surveying and Charting, 2019, 39(1):1-6.
Feng Z H. A tentative discussion on the median region gravity terrain correction method in regional gravity survey[J]. Geophysical and Geochemical Exploration, 2007, 31(5):455-458.
Yang Y B, Han G M, Liang M. Gravity near zone terrain correction precision discussion[J]. Computing Techniques for Geophysical and Geochemical Exploration, 2011, 33(1):92-97.
Gao Z C, Wang C Y, Li Y T. Research of gravity near zone terrain correction methods using 1∶10 000 digital topographic map[J]. Computing Tehniques for Geophysical and Geochemical Exploration, 2015, 27(1):61-64.
Tang X P, Liu K H, Geng T, et al. Curved-grid kringing gridding method and its application to near-station terrain correction in gravity measurement[J]. Geophysical and Geochemical Exploration, 2015, 39(4):848-854.
Gao Y J, Liu Z Q, Wan W H, et al. Influence and verification of DEM grid spacing on the accuravy of gravity near-region terrain correction[J]. Engineering of Surveying and Mapping, 2016, 25(8):14-18.
Zhang J M, Yan J Q, Wang F M. Application of WorldDEM data in terrain correction of gravity near-region[J]. Equipment for Geophysical Prospecting, 2018, 28(2):94-98.
Liu S R, Gao P, Geng T, et al. The applicability of different sources DEM data in median region terrain correction of gravity in high mountain areas[J]. Geophysical and Geochemical Exploration, 2019, 43(5):1111-1118.
Zhao G X, Zhang G L, Su Y J, et al. An experimental study of the data measurement method for near-region terrain correction in gravity exploration[J]. Geophysical and Geochemical Exploration, 2012, 36(6):952-955.
Li Z P, Dai G K, Zhang M H. The impact and effect of DEM grid spacing on the accuracy of gravity remote topographic correction[J]. Geophysical and Geochemical Exploration, 2020, 44(6):1399-1407.
Liu S F. Determination of the maximum radius for terrain correction in regional gravity measurement[J]. Curstal Deformation and Earthquake, 1988, 8(1):55-58.
Sun X J, Jin S H. Determination of integral radius in gravitational terrain corrections[J]. Journal of Geomatics Science and Technology, 2010, 27(3):173-175.
Xu L P, Zhang G B, Li J J, et al. A study of the maximum radius in the terrain correction calculation of airborne gravity and a comparison of various calculation methods[J]. Geophysical and Geochemical Exploration, 2015, 39(S1):113-118.
[32]
曾华霖. 重力场与重力勘探[M]. 北京: 地质出版社, 2005.
[32]
Zeng H L. Gravity field and gravity exploration[M]. Beijing: Geology Press, 2005.
[33]
DZ/T 0004-2015.重力调查技术规范(1∶50 000)[S]2015.
[33]
DZ/T 0004-2015.The technical specification for gravity survey(1∶50,000)[S] 2015.
[34]
DZ/T 0171-2017.大比例尺重力勘探规范[S].
[34]
DZ/T 0171-2017.Specification for large-scale gravity survey[S].