Abstract
Satellite radar altimetry has made unique contributions to global and coastal gravity field recovery. This paper starts with a general introduction followed by the progress of satellite radar altimetry technology. Then, the methods of marine gravity field recovery and dominating gravity models are described briefly. Finally, typical gravity models are compared with shipboard gravity measurements to evaluate their accuracies in offshore and coastal regions of China. The root mean squares of deviations between gravity models and shipboard gravity are all more than 7 mGal in offshore regions and within the range of 9.5–10.2 mGal in coastal regions. Further analysis in coastal regions indicates that the new gravity models with new satellite missions including Jason-2, SARAL/Altika, and Envisat data have relatively higher accuracy, especially SARAL/Altika data, significantly improving the coastal gravity field. Accuracies are low in areas with strong currents, showing that tide correction is very important for altimetry-derived marine gravity recovery as well as shipboard measurements in coastal gravity field determination. Moreover, as an external check, shipboard gravity data need more operations to improve their precision, such as higher instrument accuracy and finer data processing.
Highlights
The gravity field is one of the most important basic physical fields of the Earth, reflecting the distribution, movement, and state change of Earth’s interior material
Simple processing is applied to directly discard the survey lines and points with large errors in the offshore area as the accuracy evaluation of marine gravity field models in the coastal region of China is the focus of this paper
Typical models V24.1 and V27.1 from San Diego (SIO), DTU10 and DTU13 from DTU, and EGM2008 were compared with shipboard gravity data to evaluate accuracies in offshore and coastal regions of China
Summary
The gravity field is one of the most important basic physical fields of the Earth, reflecting the distribution, movement, and state change of Earth’s interior material. The levels of accuracy and precision of altimetry-derived marine gravity field models, which can be derived from radar altimeter measurements of sea surface heights (Rapp, 1979; Haxby et al, 1983) or slopes (Sandwell and Smith, 1997; Andersen and Knudsen, 1998; Hwang, 1998), have greatly evolved Until now, they have demonstrated accuracy and spatial resolution at 1–2 mGal and 1′ × 1′ (approximately 2 km × 2 km), respectively and, as a result, have allowed many contemporary geophysical questions to be addressed (e.g., Fairhead et al, 2001; Bao et al, 2013; Sandwell et al, 2013; Sandwell et al, 2014; Sandwell et al, 2019; Hwang and Chang, 2014; Andersen et al, 2019; Li et al, 2020; Li et al, 2021)
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