NZVD2009 Datum Offsets
The 13 mean sea level (MSL) datums used in New Zealand are offset from the New Zealand Vertical Datum 2009 (NZVD2009) and each other. This is because the datums are defined in terms of mean sea level at their respective standard ports. The relationship of the different height surfaces is shown in the figure below.
The New Zealand Vertical Datum 2009 (NZVD2009) uses NZGeoid2009 as its reference surface.
The offsets are measured from the local levelling datum to the NZVD2009 reference surface (NZGeoid2009). The offset is positive when it is above the local datum.
| MSL Datum | NZGeoid2009 Offset (metres) | Standard Deviation (metres) |
|---|---|---|
| One Tree Point 1964 | 0.06 | 0.03 |
| Auckland 1946 | 0.34 | 0.05 |
| Moturiki 1953 | 0.24 | 0.06 |
| Gisborne 1926 | 0.34 | 0.02 |
| Napier 1962 | 0.20 | 0.05 |
| Taranaki 1970 | 0.32 | 0.05 |
| Wellington 1953 | 0.44 | 0.04 |
| Nelson 1955 | 0.29 | 0.07 |
| Lyttelton 1937 | 0.47 | 0.09 |
| Dunedin 1958 | 0.49 | 0.07 |
| Dunedin-Bluff 1960 | 0.38 | 0.04 |
| Bluff 1955 | 0.36 | 0.05 |
| Stewart Island 1977 | 0.39 | 0.15 |
These offsets can be used in conjunction with NZGeoid2009 to transform NZGD2000 ellipsoidal heights to normal-orthometric heights in terms of the MSL datums.
