Oceania Geodetic Data - Page 5

The DBL60-NZGD2000 grid enables the conversion of normal-orthometric heights from the Dunedin-Bluff 1960 local vertical datum directly to New Zealand Geodetic Datum 2000 (NZGD2000) ellipsoidal heights.

DBL60-NZGD2000 is published on a one arc-minute grid (approximately 1.8 kilometres) extending over the benchmarks that nominally define the extent of the Dunedin-Bluff 1960 vertical datum (167.4° E to 169.9° E, 45.0° S to 46.7° S).

The conversion value is represented by the attribute “delta”, in metres.

This grid is a combination of New Zealand Quasigeoid 2016 NZGeoid2016 and the DBL60-NZVD2016 height conversion grid. Where NZGeoid2016 is the reference surface for the New Zealand Vertical Datum 2016 (NZVD2016), while the DBL60-NZVD2016 grid models the difference between the Dunedin-Bluff 1960 vertical datum and NZVD2016 using the LINZ GPS-levelling marks.

More information on converting heights between vertical datums can be found on the LINZ website.

The TNK70-NZGD2000 grid enables the conversion of normal-orthometric heights from the Taranaki 1970 local vertical datum directly to New Zealand Geodetic Datum 2000 (NZGD2000) ellipsoidal heights.

TNK70-NZGD2000 is published on a one arc-minute grid (approximately 1.8 kilometres) extending over the benchmarks that nominally define the extent of the Taranaki 1970 vertical datum (173.6° E to 176.4° E, 38.3° S to 41.1° S).
The conversion value is represented by the attribute “delta”, in metres.

This grid is a combination of New Zealand Quasigeoid 2016 NZGeoid2016 and the TNK70-NZVD2016 height conversion grid. Where NZGeoid2016 is the reference surface for the New Zealand Vertical Datum 2016 (NZVD2016), while the TNK70-NZVD2016 grid models the difference between the Taranaki 1970 vertical datum and NZVD2016 using the LINZ GPS-levelling marks.

More information on converting heights between vertical datums can be found on the LINZ website.

The New Zealand Quasigeoid2009 (NZGeoid2009) can be used to convert GPS derived ellipsoidal heights to New Zealand Vertical Datum 2009 (NZVD2009) normal-orthometric heights that relate more closely to mean sea level and the local gravity field. NZGeoid2009 can also be used to transform heights to any of the 13 official local vertical datums used across New Zealand, more information on this transformation is available at www.linz.govt.nz/geodetic/conversion-coordinates/h....

NZGeoid2009 is formally defined in the LINZ standard LINZS25004 which can be obtained from www.linz.govt.nz/geodetic/standards-publications/s.... NZGeoid2009 models the difference between the GRS80 ellipsoid and the geoid over the New Zealand region. The geoid is a theoretical surface of equal gravity that roughly approximates the mean level of the sea across the Earth.

NZGeoid2009 is published by LINZ and was computed by enhancing the EGM2008 global gravity model with terrestrial gravity observations over New Zealand and DNSC08 satellite altimetry data over the oceans. The model is published on a one arc-minute grid covering New Zealand's extended exclusive economic zone.

The accuracy of NZGeoid2009 is nominally ±0.08 metres across New Zealand. More information on the accuracy in relation to the 13 local vertical datums is provided in LINZS25004.

The national airborne gravity dataset is comprised of more than 50,000 linear km of flight observations, covering the three main islands of New Zealand and up to 10km offshore.

This dataset provides a 1 arc minute raster image of the Bouguer anomalies, which have been downward continued to the ground surface (McCubbine et al, 2017).

The national airborne gravity dataset was collected as a joint project between Land Information New Zealand (LINZ), GNS Science (GNS) and Victoria University of Wellington (VUW). The airborne survey was completed in a total of eight months, over two campaigns: August – October 2013, and February – June 2014.

Users may also be interested in other layers created for the free-air anomalies at ground surface and the along track observations from the gravity flight lines at flight elevation NZ Airborne Gravity Free-Air Anomalies at Ground Surface (2013-2014) and NZ Airborne Gravity Flight Lines at Elevation (2013-2014).

McCubbine, J. Stagpoole, V. Caratori-Tontini, F. Amos, M. Smith, E. and Winefield, R. (2017). Gravity anomaly grids for the New Zealand region. Manuscript submitted for publication New ZealandJournal of Geology and Geophysics.

Introduction
This dataset provides a 1 arc minute raster image of the free-air gravity anomalies, which have been downward continued to the ground surface (McCubbine et al, 2017).

Description
Gravity anomalies are differences between measured gravity (from the airborne gravity dataset) and an ellipsoidal model of the Earth’s gravity field (GRS80). Gravity anomalies correspond to un-modelled density variations within the Earth’s crust and upper mantle. They are used to investigate concealed geological structures and for quasigeoid modelling.

These free-air anomalies show values which include gravitation impact of the topography.

The national airborne gravity dataset is comprised of more than 50,000 linear km of flight observations, covering the three main islands of New Zealand and up to 10km offshore.

As the airborne gravity dataset was measured at flight altitude, the observations have been reduced to the ground surface (a process known as downward continuation).

The national airborne gravity dataset was collected as a joint project between Land Information New Zealand (LINZ), GNS Science (GNS) and Victoria University of Wellington (VUW). The airborne survey was completed in a total of eight months, over two campaigns: August – October 2013, and February – June 2014.

Users may also be interested other layers created for Bouguer anomalies at ground surface and the along track observations from the gravity flight lines at flight elevation NZ Airborne Gravity Bouguer Anomalies at Ground Surface (2013-2014) and NZ Airborne Gravity Flight Lines at Elevation (2013-2014).

McCubbine, J. Stagpoole, V. Caratori-Tontini, F. Amos, M. Smith, E. and Winefield, R. (2017). Gravity anomaly grids for the New Zealand region. Manuscript submitted for publication New Zealand Journal of Geology and Geophysics.

New Zealand Quasigeoid 2016 Raster, provides users with a one arc-minute gridded (approximately 1.8 kilometres) raster image of the New Zealand Quasigeoid 2016 (NZGeoid2016).

The relationship between the GRS80 ellipsoid and the New Zealand Vertical Datum 2016 (NZVD2016) is modelled by [NZGeoid2016] and is represented by the attribute “N”, in metres.(data.linz.govt.nz/layer/3418).
NZVD2016 is formally defined in the LINZ standard LINZS25009.

Users may also be interested in transforming heights to any of the 13 historic local vertical datums used in New Zealand using the appropriate datum relationship grid displayed in the NZ Height Conversion Index.

More information on these transformations is available on the LINZ website.

The Dunedin-Bluff 1960 to NZVD2016 Conversion Raster provides users with a two arc-minute (approximately 3.6 kilometres) raster image of the conversion of normal-orthometric heights from the Dunedin-Bluff 1960 local vertical datum to the New Zealand Vertical Datum 2016 (NZVD2016).

The conversion value is represented by the attribute “O”, in metres.
This conversion and NZVD2016 are formally defined in the LINZ standard LINZS25009.

The height conversion grid models the difference between the Dunedin-Bluff 1960 vertical datum and NZVD2016 using the LINZ GPS-levelling marks. From the GPS-levelling marks the expected accuracy is better than 2 centimetres (95% Confidence interval).

More information on converting heights between vertical datums can be found on the LINZ website.

The Wellington 1953 to NZVD2016 Conversion Raster provides users with a two arc-minute (approximately 3.6 kilometres) raster image of the conversion of normal-orthometric heights from the Wellington 1953 local vertical datum to the New Zealand Vertical Datum 2016 (NZVD2016).

The conversion value is represented by the attribute “O”, in metres.
This conversion and NZVD2016 are formally defined in the LINZ standard LINZS25009.

The height conversion grid models the difference between the Wellington 1953 vertical datum and NZVD2016 using the LINZ GPS-levelling marks. From the GPS-levelling marks the expected accuracy is better than 2 centimetres (95% Confidence interval).

More information on converting heights between vertical datums can be found on the LINZ website.

The Napier 1962 to NZVD2016 Conversion Raster provides users with a two arc-minute (approximately 3.6 kilometres) raster image of the conversion of normal-orthometric heights from the Napier 1962 local vertical datum to the New Zealand Vertical Datum 2016 (NZVD2016).

The conversion value is represented by the attribute “O”, in metres.
This conversion and NZVD2016 are formally defined in the LINZ standard LINZS25009.

The height conversion grid models the difference between the Napier 1962 vertical datum and NZVD2016 using the LINZ GPS-levelling marks. From the GPS-levelling marks the expected accuracy is better than 2 centimetres (95% Confidence interval).

More information on converting heights between vertical datums can be found on the LINZ website.

The Dunedin 1958 to NZVD2016 Conversion Raster provides users with a two arc-minute (approximately 3.6 kilometres) raster image of the conversion of normal-orthometric heights from the Dunedin 1958 local vertical datum to the New Zealand Vertical Datum 2016 (NZVD2016).

The conversion value is represented by the attribute “O”, in metres.
This conversion and NZVD2016 are formally defined in the LINZ standard LINZS25009.

The height conversion grid models the difference between the Dunedin 1958 vertical datum and NZVD2016 using the LINZ GPS-levelling marks. From the GPS-levelling marks the expected accuracy is better than 2 centimetres (95% Confidence interval).

More information on converting heights between vertical datums can be found on the LINZ website.