GEOMET spatial metadata, Geoscience Australia

Australian Geomagnetic Reference Field (2000 revision AGRF00) (National Geoscience Dataset)

Note : This dataset description is metadata (data about data) which describes the actual dataset in accordance with the ANZLIC (Australia New Zealand Land Information Council) Core Metadata Guidelines Version 2.

Dataset citation

ANZLIC unique identifier: ANZCW0703002396
Title: Australian Geomagnetic Reference Field (2000 revision AGRF00) (National Geoscience Dataset)

Custodian

Custodian: Geoscience Australia
Jurisdiction: Australia

Description

Abstract: The AGRF is a numerical model of the earths magnetic field over the Australian region. The model can be used to generate single point or gridded values of any element of the magnetic field (e.g., magnetic declination, inclination, or total intensity) together with annual change estimates. The AGRF is valid only for the Australian region, where it is considered to be more accurate than global models such as the International Geomagnetic Reference Field. The version here, AGRF00, is valid for years between 1995 and 2005. AGRF is also provided online. The user must input the latitude, longitude, and elevation of a site together with the year. http:/www.agso.gov.au/geophysics/geomag/rf/agrfform.html FURTHER INFORMATION:- The AGRF represents a combination of the earths main (core) field and the long wavelength crustal field. Local crustal anomolies and disturbances which are external in origin (e.g. magnetic storms) are not represented. The model is based on all available ground, airborne, and satellite vector survey data. Magnetic observatory and repeat station survey data from the region are used to update these main/crustal field data sets and to provide the estimates of annual change. The region modelled is a spherical cap of radius 28 deg centred at 24 degS, 135 degE. Model values outside a radius of 24 deg are considered to be unreliable because of edge effects.

ANZLIC search words and qualifiers:

- GEOSCIENCES

- GEOSCIENCES Geophysics

Geographic extent name: AUSTRALIA EXCLUDING EXTERNAL TERRITORIES - AUS - Australia

Note: The format for each Geographic extent name is: Name - Identifier - Category - Jurisdiction (as appropriate) See GEN Register

Geographic bounding box:

North bounding latitude: 0

South bounding latitude: -48

East bounding longitude: 161

West bounding longitude: 108

Data currency

Beginning date: 1995-01-01
Ending date: 2005-01-01

Dataset status

Progress: Complete
Maintenance and update frequency: continual

Access

Stored data format:

DIGITAL: ArcGIS-coverage ArcInfo coverage Geographic WGS84

Available data format:

DIGITAL: dat Data file MapInfo Geographic WGS84

DIGITAL: shp ArcView shape file ArcView Geographic WGS84

DIGITAL: ArcGIS-coverage ArcInfo coverage Geographic WGS84

Access constraints: Free to download

Data quality

Lineage:
The formal AGRF series of potential field models started in 1985, although hand-contoured charts and polynomial models for the Australian region were produced well before this date. Rectangular harmonic analysis was used for AGRF85, and spherical cap harmonic analysis for AGRF90, AGRF95 and AGRF00. The models include prospective estimates of the annual change of the vector field, and have to be updated every 5 years. These datasets are derived from contouring a grid of ASCII data derived from AGSO's AGRF software, using Arcinfo.

Positional accuracy:
Nominal Scale 1:100,000

Attribute accuracy:
High

Logical consistency:
A geoscientist visually inspected the finished dataset to make sure the attributes were accurate and the data were consistent spatially with current scientific information. Tests are also carried out on these data for data completeness, correct spatial representation, attribute accuracy, logical consistency and correctness, and where appropriate for compliance with Geoscience Australia's GIS data dictionary.

Completeness:
The dataset coverage is complete for the whole of continental Australia.

Contact information

Contact organisation: Commonwealth of Australia (Geoscience Australia)
Acronym: GA
Position: Manager Client Services
Address: Cnr Jerrabomberra Ave and Hindmarsh Dr
Address: GPO Box 378
Suburn: Canberra
State: ACT
Country: Australia
Postcode: 2601
Phone: 02 6249 9966
Fax: 02 6249 9960
Email: sales@ga.gov.au

Metadata information

Metadata date: 1998-11-13 00:00:00.0

Additional metadata

The current AGRF model is composed of two parts: AGRFMD : Contoured magnetic declination of the earths magnetic field polygon items (AGRFMD) feature feature type MAG_DEC_RNGE for valid ranges ufi unique numeric identifier magdec_min minimum magnetic declination in decimal degrees for that polygon magdec_max maximum magnetic declination in decimal degrees for that polygon line items (AGRFMD) feature feature type AGRF_BDY for the boundary and MAG_DEC_CONT for valid contours ufi unique numeric identifier mag_declin magnetic declination of the earths magnetic field in decimal degrees AGRFSV : Contoured secular variation (annual change) of magnetic declination of the earths magnetic field polygon items (AGRFSV) feature feature type SV_DEC_RANGE for valid ranges ufi unique numeric identifier sv_dec_min minimum secular variation of declination in minutes-of-arc per year for that polygon sv_dec_max maximum secular variation of declination in minutes-of-arc per year for that polygon line items (AGRFSV) feature feature type AGRF_BDY for the boundary and SEC_VAR_CONT for valid contours ufi unique numeric identifier sec_var_dec secular variation of magnetic declination of the earths magnetic field in minutes-of-arc per year

Authors:
Barton, C. , Lewis, A. , Kilgour, B.

This report was generated on 19 May 2013.

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