Product catalogue
Magnetic Anomaly Map of Australia, Seventh Edition, 2020 - Enhanced Products Package - TMI RTP AS grid
Total magnetic intensity (TMI) data measures variations in the intensity of the Earth's magnetic field caused by the contrasting content of rock-forming minerals in the Earth crust. Magnetic anomalies can be either positive (field stronger than normal) or negative (field weaker) depending on the susceptibility of the rock. The data are processed via standard methods to ensure the response recorded is that due only to the rocks in the ground. The results produce datasets that can be interpreted to reveal the geological structure of the sub-surface. The processed data is checked for quality by GA geophysicists to ensure that the final data released by GA are fit-for-purpose.
This Magnetic Anomaly Map of Australia, Seventh Edition, 2020 - Enhanced Products Package - TMI RTP AS grid is a analytic signal of the Total Magnetic Intensity grid for the Magnetic Anomaly Map of Australia, Seventh Edition, 2019.
The 2019 Total magnetic Intensity (TMI) grid of Australia has a grid cell size of ~3 seconds of arc (approximately 80 m) and only includes airborne-derived TMI data for onshore and near-offshore continental areas.
Since the sixth edition was released in 2015, data from 234 new surveys have been added to the database, acquired mainly by the State and Territory Geological Surveys. The 2019 grid was derived from a re-levelling of the national magnetic grid database. The survey grids were levelled to each other, and to the Australia Wide Airborne Geophysical Survey (AWAGS), which serves as a baseline to constrain long wavelengths in the final grid. It is estimated that 33 500 000 line-kilometres of survey data were acquired to produce the 2019 grid data, about 2 000 000 line-kilometres more than for the previous edition. The VRTP processing followed a differential reduction to pole calculation up to 5th order polynomial. Magnetic inclination and declination were derived from the IGRF-15 geomagnetic reference model using a data representative date and elevation representative of the survey. An analytic signal was calculated by applying a fast Fourier transform (FFT) process to the Total Magnetic Intensity grid of the Magnetic Anomaly Map of Australia, Seventh Edition, 2019 to produce this grid. The Analytic Signal is the square root of the sum of the two horizontal derivative and the vertical derivative. This analytic signal grid has a cell size of 0.00083 degrees (approximately 88m) and units of nanoTesla per km (or nT/km).
Simple
Identification info
- Date (Creation)
- 2020-10-31T00:00:00
- Date (Publication)
- 2020-10-31T00:00:00
- Date (Revision)
- 2021-01-21T22:31:35
- Cited responsible party
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Role Organisation / Individual Name Details Author Geophysical Acquisition & Processing Section
- Status
- Completed
- Point of contact
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Role Organisation / Individual Name Details Point of contact Commonwealth of Australia (Geoscience Australia)
Voice
- Topic category
-
- Geoscientific information
Extent
))
Temporal extent
- Time period
- 2019-01-01T00:00:00 2019-12-31T00:00:00
- Maintenance and update frequency
- Not planned
Resource format
- Title
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Product data repository: Various Formats
- Website
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Data Store directory containing the digital product files
Data Store directory containing one or more files, possibly in a variety of formats, accessible to Geoscience Australia staff only for internal purposes
- theme.ANZRC Fields of Research.rdf
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EARTH SCIENCES
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- Data centre
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NCI
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- Discipline
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Earth sciences
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- Discipline
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geophysics
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- Feature type
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grid
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- Place
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Australia
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- Place
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None
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- Project
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survey 1324
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- Theme
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AWAGS
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- Theme
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GADDS2.0
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- Theme
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magnetics
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- Theme
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analytic signal
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- Theme
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magnetism
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- Theme
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palaeomagnetism
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- Theme
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airborne digital data
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- Theme
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geophysical survey
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- Theme
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mag
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- Theme
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AS
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- Theme
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RTP
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- Theme
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VRTP
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- Theme
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grid
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- Theme
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raster
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- Keywords
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Published_External
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Resource constraints
- Title
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Creative Commons Attribution 4.0 International Licence
- Alternate title
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CC-BY
- Edition
-
4.0
- Access constraints
- License
- Use constraints
- License
- Other constraints
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© Commonwealth of Australia (Geoscience Australia) 2020
Resource constraints
- Title
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Australian Government Security ClassificationSystem
- Edition date
- 2018-11-01T00:00:00
- Classification
- Unclassified
- Language
- English
- Character encoding
- UTF8
Distribution Information
- Distributor contact
-
Role Organisation / Individual Name Details Distributor Geoscience Australia
Voice
- OnLine resource
-
File available for download in various formats from the GADDS2 portal
The Geophysical Archive Data Delivery System (GADDS2) portal provides HTTP download of geophysics datasets in a number of formats. Point and line datasets are available in NetCDF and ASEG-GDF2. Grid datasets are available in NetCDF, GeoTIFF and ERS.
- Distribution format
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WWW:LINK-1.0-http--link
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- Distributor contact
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Role Organisation / Individual Name Details Distributor National Computational Infrastructure
Voice
- OnLine resource
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/g/data/iv65/Geoscience_Australia_Geophysics_Reference_Data_Collection/national_geophysical_compilations/Magmap2019/Magmap2019-grid-tmi_rtp_as-AWAGS_MAG_2019.nc file at NCI
Fully qualified pathname of NetCDF file on NCI filesystem for Magnetic Anomaly Map of Australia, Seventh Edition, 2020 - Enhanced Products Package - TMI RTP AS grid. Users must be logged onto the NCI network to access this file system.
- Distribution format
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FILE:GEO
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- Distributor contact
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Role Organisation / Individual Name Details Distributor National Computational Infrastructure
Voice
- OnLine resource
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/g/data/iv65/Geoscience_Australia_Geophysics_Reference_Data_Collection/national_geophysical_compilations/Magmap2019/Magmap2019-grid-tmi_rtp_as-AWAGS_MAG_2019.nc file download
File download for Magnetic Anomaly Map of Australia, Seventh Edition, 2020 - Enhanced Products Package - TMI RTP AS grid
- Distribution format
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WWW:LINK-1.0-http--link
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Resource lineage
- Statement
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This Magnetic Anomaly Map of Australia, Seventh Edition, 2020 - Enhanced Products Package - TMI RTP AS grid is an analytic signal grid of the Total Magnetic Intensity (TMI) variable reduced to the pole (VRTP) anomaly for the Magnetic Anomaly Map of Australia, Seventh Edition, 2019. The data were acquired under the project No. 1324. The 2019 Total magnetic Intensity (TMI) grid of Australia (Poudjom Djomani et al., 2019) has a grid cell size of ~3 seconds of arc (approximately 80 m). This grid only includes airborne-derived TMI data for onshore and near-offshore continental areas.
Since the sixth edition was released in 2015, data from 234 new surveys have been added to the database, acquired mainly by the State and Territory Geological Surveys. The new grid was derived from a re-levelling of the national magnetic grid database. The survey grids were levelled to each other, and to the Australia Wide Airborne Geophysical Survey (AWAGS) (Milligan et al., 2009), which serves as a baseline to constrain long wavelengths in the final grid. The levelling and grid-merging procedure was described in detail in Minty et al. (2003). It is estimated that 33 500 000 line-kilometres of survey data were acquired to produce the 2019 grid data, about 2 000 000 line-kilometres more than for the previous edition. The VRTP processing followed a differential reduction to pole calculation up to 5th order polynomial. Magnetic inclination and declination were derived from the IGRF-15 geomagnetic reference model using a data representative date and elevation representative of the survey. An analytic signal was calculated by applying a fast Fourier transform (FFT) process to the Total Magnetic Intensity grid of the Magnetic Anomaly Map of Australia, Seventh Edition, 2019 survey to produce this grid. The Analytic Signal is the square root of the sum of the two horizontal derivative and the vertical derivative. This grid was calculated using an algorithm from the INTREPID Geophysics software package. The processed data are checked by GA geophysicists using standard methods for assessing quality to ensure that the final data are fit-for-purpose. The analytic signal grid is independent of the inclination of the magnetic field. It's advantage is in locating the centre and boundary of magnetised bodies. The analytic signal grid has a cell size of 0.00083 degrees (approximately 88m) and units of nanoTesla per km (or nT/km). Details of the specifications of individual airborne surveys can be found in the Fourteenth Edition of the Index of Airborne Geophysical Surveys (Percival, 2014). This Index is also available online at http://pid.geoscience.gov.au/dataset/79134.
References:
Intrepid Geophysics, http://www.intrepid-geophysics.com;
Milligan, P.R., Minty, B.R.S., Richardson, M. and Franklin, R., 2009. The Australia-wide Airborne Geophysical Survey accurate continental magnetic coverage. Preview, No. 138, p. 1-128.
Minty, B.R.S., Milligan, P.R., Luyendyk, A.P.J. and Mackey, T., 2003. Merging airborne magnetic surveys into continental-scale compilations. Geophysics, 68 (3), 988-995.
Percival, P.J., 2014. Index of airborne geophysical surveys (Fourteenth Edition);
Poudjom Djomani, Y., Minty, B.R.S., Hutchens, M., Lane, R.J.L. 2019, Total Magnetic Intensity (TMI) Grid of Australia 2019 - seventh edition - 80 m cell size. Geoscience Australia, Canberra. http://dx.doi.org/10.26186/5e9cf3f2c0f1d, eCat record number 131505.
- Hierarchy level
- Dataset
- Description
-
This Magnetic Anomaly Map of Australia, Seventh Edition, 2020 - Enhanced Products Package - TMI RTP AS grid includes airborne-derived TMI variable reduced to the pole (VRTP) data for the Magnetic Anomaly Map of Australia, Seventh Edition, 2019.
Reference System Information
- Reference system identifier
- EPSG/GDA94 (EPSG:4283)
Metadata constraints
- Title
-
Australian Government Security Classification System
- Edition date
- 2018-11-01T00:00:00
- Classification
- Unclassified
Metadata
- Metadata identifier
-
urn:uuid/7ae2a653-28eb-4a8b-9988-3b798179485e
- Title
-
GeoNetwork UUID
- Language
- English
- Character encoding
- UTF8
- Contact
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Role Organisation / Individual Name Details Point of contact Commonwealth of Australia (Geoscience Australia)
Voice Point of contact Manager Client Services
- Title
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Geophysical Data Collection - Airborne Geophysics
- Citation identifier
- c6b58f54-102c-19e9-e044-00144fdd4fa6
- Citation identifier
- 74512
Type of resource
- Resource scope
- Dataset
- Name
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Magnetic Anomaly Map of Australia, Seventh Edition, 2020 - Enhanced Products Package - TMI RTP AS grid
Alternative metadata reference
- Title
-
Geoscience Australia - short identifier for metadata record with
uuid
- Citation identifier
- eCatId/144750
- Date info (Creation)
- 2020-12-23T00:00:00
- Date info (Revision)
- 2020-12-23T00:00:00
Metadata standard
- Title
-
AU/NZS ISO 19115-1:2014
Metadata standard
- Title
-
ISO 19115-1:2014
Metadata standard
- Title
-
ISO 19115-3
- Title
-
Geoscience Australia Community Metadata Profile of ISO 19115-1:2014
- Edition
-
Version 2.0, September 2018
- Citation identifier
- https://pid.geoscience.gov.au/dataset/ga/122551