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Assessment of the latest generation GOCE-based global gravity field models using height and free-air gravity anomalies over South Africa

  • Patroba Achola OderaEmail author
Original Paper
  • 103 Downloads

Abstract

The latest Gravity field and steady-state Ocean Circulation Explorer (GOCE) global gravity field models (GGMs) are evaluated over South Africa using 118 GPS/levelling, 507 gravity and 88,968 SAGEOID10 data points. It is observed that GOCE data can improve quasi-geoid model in the long-to-medium wavelength components over South Africa. GOCE-based GGMs perform better than EGM2008 in recovering height anomalies up to 240°. Related results are obtained for free-air gravity anomalies, but the improvement over EGM2008 by GOCE data is only up to 180°. TIM5 (up to 240°) is selected as a candidate GOCE model and combined with EGM2008 (from 241 up to 2190°). This model (TIM5/EGM2008) is evaluated by observed data (GPS/levelling and gravity) and the latest hybrid quasi geoid model over South Africa (SAGEOID10). The solutions converge at 1200 and 1800° for height and free-air gravity anomalies, respectively, when TIM5/EGM2008 is used. Results show that TIM5/EGM2008 can effectively recover height and free-air gravity anomalies over South Africa. The standard deviations of the differences between observed (118 GPS/levelling and 507 gravity points) and TIM5/EGM2008 implied height and free-air gravity anomalies are ± 23.7 cm and ± 9.0 mGal, respectively. In addition, the standard deviation of the differences between SAGEOID10 and TIM5/EGM2008 implied height anomalies (at 88,968 grid points) is ± 21.7 cm. The results for height anomalies from TIM5/EGM2008 are comparable with the latest gravimetric quasi-geoid model over South Africa.

Keywords

Height anomaly Free-air gravity anomaly SAGEOID10 GPS/levelling GOCE EGM2008 

Notes

Acknowledgments

This study is supported by a start-up grant from the University of Cape Town’s research committee (URC). The following organizations are appreciated for directly providing or making data freely available on their websites: National Geospatial Information (GPS/levelling and SAGEOID10), Council for Geoscience (gravity) and Centre for Global Gravity Field Models (GOCE-GGMs and EGM2008). The author is grateful to the two anonymous reviewers, for their constructive comments, suggestions and questions that have been used to improve the quality of the paper.

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Copyright information

© Saudi Society for Geosciences 2019

Authors and Affiliations

  1. 1.Division of Geomatics, School of Architecture, Planning and GeomaticsUniversity of Cape TownRondeboschSouth Africa

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