In Taiwan, TWVD2001 and LAT are the official vertical datum. TWVD2001 is derived from the tidal information of Keelung Tide Station from 1957 to 1991 under the standard atmosphere environment of January 1, 1990. TWCD2021 has been announced in 2021. The tide observation records from 33 long-term tide gauges of the complete 19-year astronomical tide cycle from 2003 to 2021 were modeled by reconciling the tide observation records from 1993 to 2020. Lat is a part of TWCD2021, and there are other vertical daum(HAT, MSL and others) and transformation interval(e.g. SEP model).

The data includes as following:

1. Tide gauge
2. Bench Marks
3. TaiWaN Tide model (The mean sea surface model was derived using satellite altimetry observation data from 1992 to 2019, the mean sea surface data from long-term tide stations, and the geoid model (TWHYGEO2014) published by the Ministry of the Interior. The interpolation was performed using the minimum curvature method with a spatial resolution of 30 seconds to obtain the mean sea surface model relative to the reference time of 2005.0. The mean sea surface model was then re-estimated relative to the reference time of 2012.0.) If you want to know the detailed, please refer to MOI website.(https://www.land.moi.gov.tw/upload/d5-202204151442005.pdf)

                           The relationship between all vertical datum