The gravimetric geoid of Taiwan: TWGEOID18g

The geoid model for Taiwan, including the Kinmen and Matzu islands, covers the area 118°E–125°E and 21°N–27°N with a grid resolution of 30" x 30". The gravimetric model is based on land, shipborne and airborne gravity data, as well as marine gravity derived from satellite altimetry. After merging data by least-squares collocation, a remove-restore procedure is applied. First height anomalies are computed by 1D FFT with Wong-Gore modification of the Stokes kernel and then they are converted into the geoid heights. The reference global gravity model is EGM2008 up to degree and order 2190. The used digital terrain model is derived from several photogrammetric surveys at a resolution of 3"×3" and 9"×9" for the inner and outer zone, respectively. The gravimetric model fits the GPS/levelling control points with a standard deviation of 7.9 cm (and a mean difference of 21.9 cm). The geoid model is provided in ISG format 2.0 (ISG Format Specifications), while the file in its original data format is available at the model ISG webpage.