23 Jun 2023
 | 23 Jun 2023
Status: this preprint is currently under review for the journal ESSD.

Global Marine Gravity Gradient Tensor Inverted from Altimetry-derived Deflection of the Vertical: CUGB2023GRAD

Richard Fiifi Annan, Xiaoyun Wan, Ruijie Hao, and Fei Wang

Abstract. Geodetic applications of altimetry have largely been inversions of gravity anomaly. Literatures wherein Earth’s gravity gradient tensor has been studied mostly presented only the vertical gravity gradient. However, there are six unique signals that constitute the gravity gradient tensor. Gravity gradients are signals suitable for detecting short-wavelength topographic and tectonic features. They are derived from double differentiation of the geoid (or disturbing potential); and hence, are susceptible to noise amplification which was exacerbated by low across-track resolution of altimetry data in the past. However, current generation of altimetry observations have improved spatial resolutions, with some better than 5 km. Therefore, this study takes advantage of current high-resolution altimetry datasets to present CUGB2023GRAD, a global (latitudinal limits of ±80º) 1 arc-minute model of Earth’s gravity gradient tensor over the oceans using deflection of the vertical as inputs in the wavenumber domain. The results are first assessed via Laplace’s equation; whereby the resultant residual gradient is virtually zero everywhere except at high latitudes – icy environments known for contaminating altimetry observations. Due to the absence of similar models from other institutions, the results are further assessed by comparing the vertical tensor component, Tzz, with equivalent models from Scripps Institution of Oceanography (SIO) and Technical University of Denmark (DTU). The DTU equivalents were derived by multiplying their gravity anomalies by 2 πk in the wavenumber domain. Analysis showed that the inverted Tzz averagely deviates from the DTU and SIO equivalents by 0.09 and 0.18 E with corresponding standard deviations of 3.55 and 6.96 E, respectively. Bathymetric coherence analysis of Tzz over a section of the western Pacific showed comparable results with the reference models. This study proves that current generation of altimetry geodetic missions can effectively resolve Earth’s gravity gradient tensor. The CUGB2023GRAD model data can be freely accessed at (Annan et al., 2023).

Richard Fiifi Annan et al.

Status: open (until 29 Oct 2023)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • CC1: 'Comment on essd-2023-85', Jinyun Guo, 30 Jun 2023 reply
    • CC2: 'Reply on CC1', Xiaoyun Wan, 18 Sep 2023 reply
  • RC1: 'Comment on essd-2023-85', Walter Smith, 03 Jul 2023 reply
  • RC2: 'Comment on essd-2023-85', Anonymous Referee #2, 12 Aug 2023 reply

Richard Fiifi Annan et al.

Data sets

Global Marine Gravity Gradient Tensor Inverted from Altimetry-derived Deflection of the Vertical: CUGB2023GRAD Richard Fiifi Annan; Xiaoyun Wan; Ruijie Hao; Fei Wang

Richard Fiifi Annan et al.


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Short summary
Gravity gradient tensor – set of six unique gravity signals – are suitable for detecting undersea features; but due to poor spatial resolution in past years, it has received less research interest and investment. However, current datasets have better accuracies and resolutions; thereby, necessitating a revisit. Analysis shows comparable results with reference models. We conclude that current available altimetry datasets can precisely invert all six gravity gradients.