New gravimetric-only and hybrid geoid models of Taiwan for height modernisation, cross-island datum connection and airborne LiDAR mapping
Embargo Lift Date
MetadataShow full item record
© 2020, Springer-Verlag GmbH Germany, part of Springer Nature.
This paper combines gravity data collected from airborne, shipborne and terrestrial surveys and those derived from satellite altimetry to determine a high-resolution gravimetric and hybrid geoid model (on a 30” × 30″ grid) in and around Taiwan. Some 6000 new land gravity values at a 0.03-mGal precision make a notable contribution to the geoid modeling. Shipborne gravity data in waters 20 km offshore Taiwan were collected to improve the coastal geoid precision. In a circular area of 50 km around each of the five major tide gauges in Taiwan, gravity data were measured to improve vertical datum connections between Taiwan and its four offshore islands. Height anomalies were computed first and then converted to geoid heights. At > 2000 benchmarks, we obtained measured geoid heights to assess the gravimetric-only geoid and to create a hybrid geoid. Our assessments and formal errors from least-squares collocation indicate few cm of standard deviations for both geoid models, but the gravimetric geoid has mean differences of up to 20 cm with the measured geoidal heights. The hybrid geoid is used in RTK-VBS orthometric heighting, achieving a 5-cm precision. The gravimetric geoid is used to determine the relative differences in the ocean’s mean dynamic topography (MDT) between Taiwan and the four offshore islands, which are also compared with those from oceanic and altimetric methods for estimating MDT. Differences in MDT help to identify 41.7 cm and 54.1 cm offsets in the current vertical datums of Penghu and Lanyu islands. In a low-lying, flood-prone region of southern Taiwan, the hybrid geoid improves LiDAR mapping of sub-zero elevation zones by 20 cm, corresponding to 70 years of sea level rise at an assumed rate of 0.286 cm/yr.
Showing items related by title, author, creator and subject.
Amos, Matthew (2007)One goal of modern geodesy is the global unification of vertical datums so that height data from them can be properly integrated. This thesis studies the unification of the 13 disparate levelling- and tide-gauge-based ...
Filmer, Michael Shaun (2010)The Australian Height Datum (AHD) was established in 1971, and is the basis for all physical heights in Australia. However, a complete revision of the AHD has never occurred, despite problems that, although not always ...
An evaluation of FFT geoid determination techniques and their application to height determination using GPS in Australia.Zhang, Kefei (1997)A new, high resolution, high precision and accuracy gravimetric geoid of Australia has been produced using updated data, theory and computational methodologies. The fast Fourier transform technique is applied to the ...