New Zealand Quasigeoid 2005 (NZGeoid05)

The geoid is an undulating surface that is related to the Earth's gravitational field that approximates level of the seas over the entire Earth within a few metres. Because it is related to gravity, it is a more intuitive reference surface than the ellipsoid.

The New Zealand Geoid 2005 (NZGeoid05) was calculated by LINZ to provide a national geoid model with a higher resolution and accuracy than is available from the EGM96 global model.

NZGeoid05 datum offsets

The 13 mean sea level (MSL) datums used in New Zealand are offset from the NZGeoid05 and each other. more...

The NZGeoid05 can be used to convert heights between ellipsoidal (NZGD2000) and mean sea level datums using the datum offsets.

NZGeoid05 is produced on a two arc-minute grid (approximately 3.7 kilometres) over the New Zealand continental shelf (160° E to 170° W, 25° S to 60° S). It has an expected accuracy of 8 centimetres based on comparisons with GPS-levelling derived geoid values in New Zealand. It was calculated by enhancing a global geopotential model using a combination of land, sea and satellite based gravity observations. GPS-levelling observations were not used to compute NZGeoid05.

The NZGeoid05 model is available for download as either an ASCII grid (zip 2.4MB) or coordinate triplets (zip 5.1MB) for the entire computation area (160° E - 170° W; 25°S - 60°S). It can also be interpolated using the online coordinate conversion utility.