Contribution of GRAV-D airborne gravity to improvement of regional gravimetric geoid modelling in Colorado, USA

Abstract

This paper studies the contribution of airborne gravity data to improvement of gravimetric geoid modelling across the mountainous area in Colorado, USA. First, airborne gravity data was processed, filtered, and downward-continued. Then, three gravity anomaly grids were prepared; the first grid only from the terrestrial gravity data, the second grid only from the downward-continued airborne gravity data, and the third grid from combined downward-continued airborne and terrestrial gravity data. Gravimetric geoid models with the three gravity anomaly grids were determined using the least-squares modification of Stokes’ formula with additive corrections (LSMSA) method. The absolute and relative accuracy of the computed gravimetric geoid models was estimated on GNSS/levelling points. Results exhibit the accuracy improved by 1.1 cm or 20% in terms of standard deviation when airborne and terrestrial gravity data was used for geoid computation, compared to the geoid model computed only from terrestrial gravity data. Finally, the spectral analysis of surface gravity anomaly grids and geoid models was performed, which provided insights into specific wavelength bands in which airborne gravity data contributed and improved the power spectrum.

High-Resolution Gravity Measurements on Board an Autonomous Underwater Vehicle: Data Reduction and Accuracy Assessment

“…The accuracy of GraviMob measurements can be then assessed using the downward continued shipborne data. In this study, the Least-Squares Collocation (LSC) approach [20] adapted to the Remove-Compute-Restore (RCR) method was used as it offers several advantages [21][22][23][24][25]. This method enables interpolation anywhere in the 3D space and input data do not need to be at the same height/depth.…”

“…The shipborne gravity data are therefore downward continued to the measurement depth. Among gravity data processing techniques, DC is considered one of the most unstable procedures [24]. Therefore, to improve the accuracy of the procedure we used the RCR technique, i.e., instead of the gravity anomalies, the residual shipborne gravity anomalies were used.…”

“…𝑀𝑒𝑎𝑛 𝑔𝑟𝑎𝑣𝑖𝑡𝑦 𝑎𝑛𝑜𝑚𝑎𝑙𝑦 𝑑𝑖𝑓𝑓𝑒𝑟𝑒𝑛𝑐𝑒𝑠 𝑏𝑒𝑡𝑤𝑒𝑒𝑛 𝐷𝑊𝐶 𝑠ℎ𝑖𝑝𝑏𝑜𝑟𝑛𝑒 𝑎𝑛𝑑 𝐺𝑟𝑎𝑣𝑖𝑀𝑜𝑏 𝑀𝑒𝑎𝑛 𝑡𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒 𝑑𝑖𝑓𝑓𝑒𝑟𝑒𝑛𝑐𝑒𝑠 𝑏𝑒𝑡𝑤𝑒𝑒𝑛 𝑠𝑒𝑛𝑠𝑜𝑟 𝑡𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒 𝑎𝑛𝑑 𝑇 (24) The gradients of the four profiles are listed in Table 3. Good agreement is obtained for the gradients of the four profiles.…”

“…Mean gravity anomaly di f f erences between DWC shipborne and GraviMob Mean temperature di f f erences between sensor temperature and T 0 (24) The gradients of the four profiles are listed in Table 3. Good agreement is obtained for the gradients of the four profiles.…”

A High-Resolution Gravimetric Geoid Model for Kuwait Using the Least-Squares Collocation

“…A high-resolution geoid should be determined to be able to deal with GNSS height accuracy levels that allow the orthometric height to be derived by integrating Geoid and GNSS (Hofmann-Wellenhof and Moritz, 2006). The computation of regional gravimetric geoids has increased in recent years (Huang and Véronneau, 2013;Zaki, 2015;Zaki, 2018;Matsuo and Kuroishi, 2020;Saadon et al, 2021;Varga et al, 2021;Zaki and Mogren, 2021). Geoid determination theory and methods have been improved (Moritz, 1978;Forsberg and Sideris, 1993;Sjöberg, 2003;Ellmann and Vaníček, 2007;Shen and Han, 2013); the availability of accurate and high-resolution digital elevation and digital bathymetry models (Hennig et al, 2001;Olson et al, 2014), the computation of accurate global geopotential models (Pavlis, 2008;Förste et al, 2015;Zingerle et al, 2020), the prospect of fitting the gravimetric geoid model with the GNSS/leveling and using diverse data efficiently are the major factors that made the computation of accurate geoid model possible (Erol, 2007;Kaloop et al, 2018;Kaloop et al, 2020;Kaloop et al, 2021).…”