Improving gravity anomalies over China marginal sea from retracked Geosat and ERS-1 data

Haihong Wang*, Yuande Yang, Chein-way Hwang, Yonghai Chu, Xinying Ma

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The quality of altimeter data and ocean tide model is critical to the recovery of coastal gravity anomalies. In this contribution, three retracking methods (threshold, improved threshold and Beta-5) are investigated with the aim of improving the altimeter data over a shallow water area. Comparison indicates that the improved threshold is the best retracking method over China Sea. Two ocean tide models, NAO99b and CSR4.0, are analyzed. Results show that different tide models used in the processing of altimeter data may result in differences more than 10 mGal in recovered coastal gravity anomalies. Also, NAO99b is more suitable than CSR4.0 over the shallow water area of China Sea. Finally, gravity anomalies over China Sea are calculated from retracked Geosat/GM and ERS-1/GM data by least squares collocation. Comparison with shipborne gravimetry data demonstrates that gravity anomalies from retracked data are significantly superior to those from non-retracked data. Our results have the same order as the other two altimeter-derived gravity models: Sandwell&Smith(V16) and DNSC08.

Original languageEnglish
Pages (from-to)144-149
Number of pages6
JournalGeo-Spatial Information Science
Issue number2
StatePublished - 1 Jun 2010


  • China marginal sea
  • Gravity anomaly
  • Satellite altimetry
  • Tide model
  • Waveform retracking

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