[G02-5] Altimetry and marine geoid

[G02-5-04] The altimetry-derived marine gravity field for enhanced geodetic and geological studies around Taiwan

^○Xiaoli Deng¹, Cheinway Hwang², Ole B. Andersen³, Mark G. Stewart¹ (1.School of Engineering, The University of Newcastle, New South Wales, Australia, 2.Department of Civil Engineering, National Chiao Tung University, Taiwan, 3.Danish National Space Centre, Technical University of Denmark, Copenhagen, Denmark)

There are, every year, earthquakes occurring around Taiwan, which can sometimes cause destruction and loss of life. As such, it has become increasingly important to understand surface deformations in southwestern Taiwan and the northern South China Sea. This paper investigate how satellite altimetry contributes to this understanding of neotectonic fields. Waveform data from the satellite altimetry geodetic mission Jason-1 are retracked. Together with data from the repeat mission Cryosat-2, the derived altimeter sea surface heights are used to model a regionally optimal marine gravity field around Taiwan. The methodologies and techniques traditionally used for local and regional gravity determination are investigated. The modelled gravity field over the study region is compared to the latest global marine gravity models (e.g., DTU15 and Sandwell's 2014 model), as well as the ship-track gravity measurements around Taiwan. The results show that accuracy of the recovered marine gravity ranges from ~3 mGal to ~7.5 mGal depending on coastal zones. The vertical gravity gradient field is also generated to detect potentially hidden geological features around Taiwan. It is shown that oceanic areas around Taiwan can benefit from this new and detailed altimetry-derived gravity field, especially in waters offshore eastern Taiwan.