Magnetic Anomaly Map of Australia, Seventh Edition, 2020 - Enhanced Products Package - upward continued grid UC16km20kmRes (UC16km20kmRes)  


Authors / CoAuthors

Geophysical Acquisition & Processing Section

Abstract

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 grid has a cell size of 0.00083 degrees (approximately 88m).The data are in nanoTesla (or nT). It is estimated that 33 500 000 line-kilometres of survey data collected by State and Territory geological surveys and Geoscience Australia were acquired to produce the 2019 national magnetic grid. The data has had a variable reduction to the pole applied to centre the magnetic anomaly over the magnetised body. 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. The upward continuation manipulates the magnetic data to enhance the large deep source anomalies and minimises shallow anomalies. To constrain long wavelengths in the grid, an independent data set, the Australia-wide Airborne Geophysical Survey (AWAGS) airborne magnetic data, was used to control the base levels of the survey grid. This survey grid is essentially levelled to AWAGS.

Product Type

dataset

eCat Id

144738

Contact for the resource

  Point of contact

Commonwealth of Australia (Geoscience Australia)  
Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
Canberra
ACT
2601
Australia

Keywords

theme.ANZRC Fields of Research.rdf
  • EARTH SCIENCES
( Data centre )
  • NCI
( Discipline )
  • Earth sciences
( Discipline )
  • geophysics
( Feature type )
  • grid
( Place )
  • Australia
( Place )
  • None
( Project )
  • survey 1324
( Theme )
  • GADDS2.0
( Theme )
  • TMI
( Theme )
  • RTP
( Theme )
  • AWAGS
( Theme )
  • national
( Theme )
  • magnetics
( Theme )
  • magnetism
( Theme )
  • palaeomagnetism
( Theme )
  • airborne digital data
( Theme )
  • geophysical survey
( Theme )
  • mag
( Theme )
  • total magnetic intensity
( Theme )
  • reduced to the pole
( Theme )
  • upward continued
( Theme )
  • grid
( Theme )
  • raster
  • Published_External

Publication Date

2020-10-31T00:00:00

Creation Date

2020-10-31T00:00:00

Security Constraints

Australian Government Security ClassificationSystem    

Classification - unclassified

Legal Constraints

Creative Commons Attribution 4.0 International Licence    

Access - license

Use - license

Status

completed

Purpose

Maintenance Information

notPlanned

Topic Category

geoscientificInformation

Series Information

Lineage

This Magnetic Anomaly Map of Australia, Seventh Edition, 2020 - Enhanced Products Package - upward continued grid UC16km20kmRes (UC16km20kmRes) is an airborne-derived upward continued Total Magnetic Intensity (TMI) Reduced to the Pole (RTP) grid for the Magnetic Anomaly Map of Australia, Seventh Edition, 2019 (Poudjom Djomani et al., 2019). The survey was acquired under the project No. 1324. The 2019 magnetic grid was derived from a complete 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). This survey grid is essentially levelled to AWAGS. It is estimated that 33 500 000 line-kilometres of survey data collected by State and Territory geological surveys and Geoscience Australia were acquired to produce the 2019 national magnetic grid. The grid has a cell size of 0.00083 degrees (approximately 88m). The data are in nanoTesla (or nT). The data has had a variable reduction to the pole applied to centre the magnetic anomaly over the magnetised body. 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. The upward continuation manipulates the magnetic data to enhance the large deep source anomalies and minimises shallow anomalies. 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. This Index is also available online at http://pid.geoscience.gov.au/dataset/79134. References: Milligan, P.R., Minty, B.R.S., Richardson, M. & 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.

Parent Information

Geophysical Data Collection - Airborne Geophysics

UUID - ddeb0fc4-32e3-4913-80f2-f4249b17a925,

eCat ID - 111301

Extents

[-43.9301, -9.0265, 105.9996, 154.6635]

Reference System

GDA94 (EPSG:4283)

Spatial Resolution

Service Information

Associations

Association Type - operatedOnBy

Magnetic Anomaly Map of Australia, Seventh Edition, 2020 - Enhanced Products Package - upward continued grid UC16km20kmRes (UC16km20kmRes) NCSS    

Association Type - operatedOnBy

Magnetic Anomaly Map of Australia, Seventh Edition, 2020 - Enhanced Products Package - upward continued grid UC16km20kmRes (UC16km20kmRes) OPeNDAP    

Association Type - operatedOnBy

Magnetic Anomaly Map of Australia, Seventh Edition, 2020 - Enhanced Products Package - upward continued grid UC16km20kmRes (UC16km20kmRes) WMS    

Association Type - operatedOnBy

Magnetic Anomaly Map of Australia, Seventh Edition, 2020 - Enhanced Products Package - upward continued grid UC16km20kmRes (UC16km20kmRes) WCS    

Downloads and Links

File available for download in various formats from the GADDS2 portal  

Magnetic Anomaly Map of Australia, Seventh Edition, 2020 - Enhanced Products Package - upward continued grid UC16km20kmRes (UC16km20kmRes) file download  

Magnetic Anomaly Map of Australia, Seventh Edition, 2020 - Enhanced Products Package - upward continued grid UC16km20kmRes (UC16km20kmRes) NCSS  

Magnetic Anomaly Map of Australia, Seventh Edition, 2020 - Enhanced Products Package - upward continued grid UC16km20kmRes (UC16km20kmRes) OPeNDAP  

Magnetic Anomaly Map of Australia, Seventh Edition, 2020 - Enhanced Products Package - upward continued grid UC16km20kmRes (UC16km20kmRes) WMS  

Magnetic Anomaly Map of Australia, Seventh Edition, 2020 - Enhanced Products Package - upward continued grid UC16km20kmRes (UC16km20kmRes) WCS  

Source Information

This Magnetic Anomaly Map of Australia, Seventh Edition, 2020 - Enhanced Products Package - upward continued grid UC16km20kmRes (UC16km20kmRes) includes airborne-derived TMI RTP upward continued data for the Magnetic Anomaly Map of Australia, Seventh Edition, 2019