Total Magnetic Intensity (TMI) Grid of Australia 2015 - sixth edition
Authors / CoAuthors
Total magnetic intensity (TMI) data measures variations in the intensity of the Earth 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 2015 Total magnetic Intensity (TMI) grid of Australia 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 fifth edition was released in 2010 data from 41 new surveys have been added to the
database, acquired mainly by the State and Territory Geological Surveys. It is estimated that
31 500 000 line-kilometres of survey data were acquired to produce the 2015 grid data, 4 500 000
line-kilometres more than for the previous edition.
Australian and New Zealand Standard Research Classification (ANZSRC)
magnetism and palaeomagnetism
airborne digital data
national geophysical compilation
Australian Government Security ClassificationSystem
Classification - unclassified
Creative Commons Attribution 4.0 International Licence
Access - license
Use - license
The 2015 magnetic grid of the Australian region is the sixth edition with a 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 fifth edition was released in 2010 data from 41 new surveys have been added to the database, acquired mainly by the State and Territory Geological Surveys. It is estimated that 31,500,000 line-kilometres of survey data were acquired to produce the grid data, 4,500,000 line-kilometres more than for the previous edition.
Matching of the grids in the database was achieved using a program called Gridmerge, which was originally developed within Geoscience Australia and has now been commercialised. This program was used to merge 41 new surveys to the 5th Edition Total Magnetic Intensity Anomaly Grid of Australia (Milligan et al., 2010).
The 5th Edition merged 795 individual grids to create the compilation and to constrain long wavelengths, an independent data set, the Australia-wide Airborne Geophysical Survey (AWAGS) airborne magnetic data, was used to control the base levels of those survey grids which overlapped the AWAGS data (Milligan et al., 2009). As the 5th Edition was used as a base grid for the Gridmerge operation, the new 6th Edition is essentially levelled to AWAGS.
The original grid was converted from ERMapper (.ers) format to netCDF4_classic format using GDAL1.11.1. The main purpose of this conversion is to enable access to the data by relevant open source tools and software. The netCDF grid was created on 2016-03-29.
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.
Milligan, P.R., Franklin, R., Minty, B.R.S., Richardson, L.M. and Percival, P.J., 2010. Magnetic Anomaly Map of Australia (Fifth Edition), 1:5 000 000 scale, Geoscience Australia, Canberra.
20170906 NetCDF file restructured to be indexed Southward-positive for improved performance and interoperability
Geophysical Data Collection - magnetics
UUID - c6b58f54-102e-19e9-e044-00144fdd4fa6,
eCat ID - 74514
WGS 84 (geocentric) (EPSG:4328)
Downloads and Links
NetCDF file download via HTTP for dataset 221dcfd8-04ee-5083-e053-10a3070a64e3
NCSS for dataset 221dcfd8-04ee-5083-e053-10a3070a64e3
Zipped ERS file download via HTTP for dataset 221dcfd8-04ee-5083-e053-10a3070a64e3
OPeNDAP service for dataset 221dcfd8-04ee-5083-e053-10a3070a64e3
WCS for dataset 221dcfd8-04ee-5083-e053-10a3070a64e3
WMS for dataset 221dcfd8-04ee-5083-e053-10a3070a64e3
Australian Geophysical Archive Data Delivery System
Download the map (ecw)
THREDDS catalog page for dataset 221dcfd8-04ee-5083-e053-10a3070a64e3
The 2015 Total Magnetic Intensity (TMI) grid of the Australia region is made of a compilation of 31,500,000 line-kilometres of survey data acquired by the Commonwealth, State and Territory Governments, the mining and exploration industry, universities and research organisations.