Tagged: LAND-Geodesy - Page 2

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 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.

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.

The STI77-NZGD2000 grid enables the conversion of normal-orthometric heights from the Stewart Island 1977 local vertical datum directly to New Zealand Geodetic Datum 2000 (NZGD2000) ellipsoidal heights.

STI77-NZGD2000 is published on a one arc-minute grid (approximately 1.8 kilometres) extending over the benchmarks that nominally define the extent of the Stewart Island 1977 vertical datum (167.2° E to 168.8° E, 46.5° S to 47.5° 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 STI77-NZVD2016 height conversion grid. Where NZGeoid2016 is the reference surface for the New Zealand Vertical Datum 2016 (NZVD2016), while the STI77-NZVD2016 grid models the difference between the Stewart Island 1977 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 deformation model associated with the NZGD2000 datum was updated, nominally at 1 August 2013. The actual update of LINZ data took place on 14-15 December 2013. This update involved reverse patches, which means that the "reference coordinates" of features were updated. The main updates relate to the Christchurch earthquakes. The patch also updated coordinates affected by other South Island earthquakes since 2000.

These updates have been incorporated into Landonline and resulted in spatial updates to all features in the affected areas.

This data set contains contours indicating the extent and magnitude of the coordinate changes to assist in assessing the impact of this update on client data sets. This dataset is also available as a multipolygon.

For more information see here

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 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.

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 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.

Coordinates computed from surveys undertaken after the 14 February 2016 Canterbury earthquake. These should be consistent with any observations made after this earthquake (neglecting any localised deformation such as that due to liquefaction).

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

These coordinates are only provisional. Analysis is ongoing as further data is collected. Coordinates were calculated using SNAP v2.5.33. Stations were constrained using coordinates of distant PositioNZ continuous GNSS stations that were unaffected by the earthquake.

The standard deviations of coordinates are 0.01m horizontally and 0.02m vertically, relative to the PositioNZ network.

Coordinate changes due to the earthquake have been calculated by comparing pre and post-earthquake coordinates. Pre-earthquake coordinates were calculated relative to public and private continuous GNSS stations. These continuous GNSS stations had data processed for several days early in 2016 (before the earthquake). Other pre-earthquake geodetic data was then readjusted with the continuous GNSS data. Note that this means these coordinate changes may differ slightly from those that would be calculated by comparing the post-earthquake coordinates with those currently in the Geodetic Database.

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