HR: 1330h
AN: G32A-0741    [PDF]
TI: Sub-Decimeter Local Geoid Model in Taiwan Mountain Belt
AU: * Jeng, D
EM: l4890105@ccmail.ncku.edu.tw
AF: Department of Earth Sciences, National Cheng Kung University, No.1, Ta-Hsueh Road, Tainan, 701 Taiwan
AU: Chen, K
AF: Department of Surveying and Geoinfomatics, National Cheng Kung University, No.1, Ta-Hsueh Road, Tainan, 701 Taiwan
AU: Tseng, C
AF: Department of Earth Sciences, National Cheng Kung University, No.1, Ta-Hsueh Road, Tainan, 701 Taiwan
AB: A first-order leveling network of 4500-km leveling lines, including 2065 benchmarks, with 2.5K$^{1/2}$ mm accuracy around Taiwan island has been established by MOI(Ministry Of the Interior) in 1998-2003. GPS measurement and gravity data were collected at each benchmark. Existing local geoid model with accuracy of 10-20 cm was calculated with observations of sea surface gradients derived from satellite altimetry, land gravity anomalies, ship gravity anomalies and the EGM96 model in Taiwan. In this paper, we combine GPS and leveling measurements described above and undulation data estimated using existing local geoid model to improve the accuracy of local geoid model of Taiwan with the least squares collocation technique. A correction signal with variance-covariance matrix related to distance between benchmarks is added into the observation equation. Correction signals of benchmarks are separated into three part: GPS height, leveling height and the undulation, by their variance-covariance matrix. The result shows that the mean difference of $\Delta$N(undulation difference) derived from our new local geoid model and GPS/leveling is 4.1cm. Our new local geoid model in the mountainous Taiwan area has an accuracy of about $\pm$3.3 cm, which is close to the accuracy of GPS, while comparing with independent near-fault GPS/leveling data.
DE: 1219 Local gravity anomalies and crustal structure
SC: Geodesy [G]
MN: 2003 Fall Meeting