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Description
Magnetic anomaly maps provide insight into the subsurface structure and composition of the Earth's crust. Anomalies trending parallel to the isochrons (lines of equal age) in the oceans reveal the temporal evolution of oceanic crust. Magnetic maps are widely used in the geological sciences and in resource exploration. Furthermore, the global magnetic map is useful in science education to illustrate various aspects of Earth evolution such as plate tectonics and crustal interaction with the deep mantle. Distinct patterns and magnetic signatures can be attributed to the formation (seafloor spreading) and destruction (subduction zones) of oceanic crust, the formation of continental crust by accretion of various terranes to cratonic areas and large scale volcanism (both on continents and oceans).
Background
EMAG2 is the result of an international collaboration with over a hundred data providers worldwide. It is a significant update of NGDC's candidate for the World Digital Magnetic Anomaly Map. The resolution has been improved from 3 arc minutes to 2 arc minutes and the altitude has been reduced from 5 km to 4 km above geoid. Additional grid and trackline data have been included, both over land and the oceans. Interpolation between sparse tracklines in the oceans was improved by directional gridding and extrapolation, based on an oceanic crustal age model. The longest wavelengths (larger than 330 km) were replaced with the latest CHAMP satellite lithospheric magnetic field model MF6
Definition
EMAG2 is specified as a global 2-arc-minute resolution grid of the anomaly of the magnetic intensity at an altitude of 4 km above mean sea level. It was compiled from satellite, marine, aeromagnetic and ground magnetic surveys.
Contributing organizations
http://geomag.org/models/EMAG2/acknowledgments.html
Visualizations of EMAG2
Google Maps: http://ngdc.noaa.gov/geomag/data/Google_Maps/EMAG2/index.html
Google Earth: http://bbs.keyhole.com/ubb/ubbthreads.php?ubb=showflat&Number=1205597
NASA World Wind: http://www.getech.com/downloads/EMAG2.htm
How to cite EMAG2
Maus, S., U. Barckhausen, H. Berkenbosch, N. Bournas, J. Brozena, V. Childers, F. Dostaler, J. D. Fairhead, C. Finn, R. R. B. von Frese, C. Gaina, S. Golynsky, R. Kucks, H. Luhr, P. Milligan, S. Mogren, D. Muller, O. Olesen, M. Pilkington, R. Saltus, B. Schreckenberger, E.Thebault, and F. Caratori Tontini, EMAG2: A 2-arc-minute resolution Earth Magnetic Anomaly Grid compiled from satellite, airborne and marine magnetic measurements, Geochem. Geophys. Geosyst., under review, http://geomag.org/info/Smaus/Doc/emag2.pdf |
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Location
90º 00.00' S - 90º 00.00' N |
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Instructions
This data set is a digital grid in zipped text format that can be displayed with standard mapping software, such as the free Generic Mapping Tools (http://gmt.soest.hawaii.edu/). See also the list of links to visualizations in the EMAG2 data set description. |
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Keywords
magnetic anomaly, global magnetic map, global magnetic grid |
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