Geodetic Data - Page 2

The WGN53-NZVD2016 grid enables 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.

WGN53-NZVD2016 is published on a two arc-minute grid (approximately 3.6 kilometres) extending over the benchmarks that nominally define the extent of the Wellington 1953 vertical datum (174.4° E to 176.4° E, 39.1° S to 41.6° S).

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 of WGN53-NZVD2016 is better than 2 centimetres (95% Confidence interval).

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

The DUN58-NZVD2016 grid enables 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.

DUN58-NZVD2016 is published on a two arc-minute grid (approximately 3.6 kilometres) extending over the benchmarks that nominally define the extent of the Dunedin 1958 vertical datum (168.4° E to 171.3° E, 43.9° S to 46.5° S).

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 of DUN58-NZVD2016 is better than 2 centimetres (95% Confidence interval).

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

The Canterbury region of New Zealand experienced a sequence of significant earthquakes during 2010 and 2011. These earthquakes occurred on 2010-09-04, 2011-02-22, 2011-06-13 and 2011-12-23. The coordinates in this layer account for all significant movements relating to these, so should be consistent with any observations made after the last earthquake to affect a given area (neglecting localised deformation such as that due to liquefaction).

Users may also be interested in the more comprehensive data in the companion layer Canterbury Earthquake Geodetic Marks (2010, 2011) - Comprehensive.

These coordinates are only provisional. Analysis is ongoing as further data is collected. Coordinates were calculated using SNAP v2.3.61. Stations were constrained using coordinates calculated by GNS Science. Some coordinates were calculated from data provided by Christchurch City Council. No precise levelling data has been used.

The estimated accuracy is 0.02m horizontally and 0.03m vertically.

The deformation model igns2011_working.grd calculated from a model (v4) provided by GNS Science on 28 April 2011 was used to remove secular deformation.

These coordinates are suitable for use in surveys and other geospatial activities in Canterbury and Christchurch.

For further information about this dataset, see the Canterbury earthquake information on the LINZ website.

The NZGD2000 Government CORS provides the locations of GNSS Continuously Operating Reference Stations operated by GNS Science under the GeoNet project (www.geonet.org.nz). Coordinates are from the LINZ Geodetic Database, in NZGD2000.

These are split into several different networks:

• PositioNZ - stations predominantly funded by LINZ, with some GeoNet funding. These provide a nationwide coverage of ~120km spacing. More info here
• GeoNet - stations funded by the GeoNet project. These are located in areas of geophysical interest, usually on the East Coast of the North Island. More info here
• SAGENZ - stations funded by the University of Otago, GNS Science, MIT, University of Colorado and UNAVCO. These Southern Alps Geodetic Experiment - New Zealand stations are generally semi-continuous sites.
• Tide Gauge - stations co-located with tide gauges at major ports. Data is managed through the GeoNet project also.

30" RINEX data from all of these sites is available from the GeoNet website

Real Time data is available from all PositioNZ stations, and some GeoNet stations. For more information, see the PositioNZ-RT website

The LTN37-NZVD2016 grid enables the conversion of normal-orthometric heights from the Lyttelton 1937 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.

LTN37-NZVD2016 is published on a two arc-minute grid (approximately 3.6 kilometres) extending over the benchmarks that nominally define the extent of the Lyttelton 1937 vertical datum (168.53° E to 174.2° E, 41.3° S to 45.1° S).

The height conversion grid models the difference between the Lyttelton 1937 vertical datum and NZVD2016 using the LINZ GPS-levelling marks. From the GPS-levelling marks the expected accuracy of LTN37-NZVD2016 is better than 2 centimetres (95% Confidence interval).

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

The Canterbury region of New Zealand experienced a sequence of significant earthquakes during 2010 and 2011. These earthquakes occurred on 2010-09-04, 2011-02-22, 2011-06-13 and 2011-12-23. Precise-levelling surveys have been carried out throughout Canterbury and Christchurch to re-establish heights after these earthquakes.

Users may also be interested in the horizontal coordinates derived from GNSS data in the companion layers Canterbury Earthquake Geodetic Marks (2010, 2011) - Comprehensive and Canterbury Earthquake Geodetic Marks (2010, 2011) - Simple

Horizontal Accuracy (standard deviation) approx 1m.
Vertical Accuracy of Lyttelton Vertical Datum 1937 heights (standard deviation) 0.005m.

Heights generated from precise levelling data undertaken to a misclose standard (mm) of 5*sqrt(k) where k is the distance in kilometres. Precise levelling in the Christchurch area was undertaken after the 23 December 2011 earthquake. Other areas were levelled after the most recent earthquake to have affected heights in that area. Heights therefore represent the position of marks accounting for all four substantial Canterbury earthquakes.

These heights are only provisional. Analysis is ongoing as further data is collected.
Heights calculated using SNAP v2.3.64.
Heights were constrained using the pre-earthquake heights at geodetic codes AC9B, AFAQ, AG32 and B853. GNSS observations and modelling indicates that the height change of these marks was negligible.
Some heights were calculated from precise levelling data provided by Christchurch City Council.

These coordinates are suitable for use in surveys and other geospatial activities in Canterbury and Christchurch.

For further information about this dataset, see the Canterbury earthquake information on the LINZ website.

The TNK70-NZVD2016 grid enables the conversion of normal-orthometric heights from the Taranaki 1970 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.

TNK70-NZVD2016 is published on a two arc-minute grid (approximately 3.6 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 height conversion grid models the difference between the Taranaki 1970 vertical datum and NZVD2016 using the LINZ GPS-levelling marks. From the GPS-levelling marks the expected accuracy of TNK70-NZVD2016 is better than 2 centimetres (95% Confidence interval).

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

The NSN55-NZGD2000 grid enables the conversion of normal-orthometric heights from the Nelson 1955 local vertical datum directly to New Zealand Geodetic Datum 2000 (NZGD2000) ellipsoidal heights.

NSN55-NZGD2000 is published on a one arc-minute grid (approximately 1.8 kilometres) extending over the benchmarks that nominally define the extent of the Nelson 1955 vertical datum (171.3° E to 174.4° E, 40.4° S to 42.7° 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 NSN55-NZVD2016 height conversion grid. Where NZGeoid2016 is the reference surface for the New Zealand Vertical Datum 2016 (NZVD2016), while the NSN55-NZVD2016 grid models the difference between the Nelson 1955 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.

Introduction
This dataset provides gravity observations, reductions and metadata for New Zealand’s national airborne gravity survey at flight elevation. A full description of each field in this dataset is available in the accompanying pdf NZ Airborne Gravity Flight Lines at Elevation (2013-2014) Description.

Description
New Zealand’s 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.

Gravity observations can be used to compute gravity anomalies: differences between measured gravity and an ellipsoidal model of the Earth’s gravity field. 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.

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 raster layers created for each of the free-Air and Bouguer Anomalies which have been downward continued to ground surface NZ Airborne Gravity Free-Air Anomalies at Ground Surface (2013-2014) and NZ Airborne Gravity Bouguer Anomalies at Ground Surface (2013-2014).

The DBL60-NZVD2016 grid enables 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.
DBL60-NZVD2016 is published on a two arc-minute grid (approximately 3.6 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 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 of DBL60-NZVD2016 is better than 2 centimetres (95% Confidence interval).

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