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EMAG2: Earth Magnetic Anomaly Grid (2-arc-minute resolution)

browse graphicEMAG2 looking north-west at Portugal/Spain from the Atlantic. Kursk (Russia) is seen as a strong anomaly in the background. The stripes on the left of the image are magnetic lineations due to sea-floor spreading.
EMAG2 is a global Earth Magnetic Anomaly Grid compiled from satellite, ship, and airborne magnetic measurements. It is a significant update of our previous candidate grid 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 the geoid. Additional grid and track line data have been included, both over land and the oceans. Wherever available, the original shipborne and airborne data were used instead of precompiled oceanic magnetic grids. Interpolation between sparse track lines in the oceans was improved by directional gridding and extrapolation, based on oceanic crustal age model. The longest wavelengths (>330 km) were replaced with the latests CHAMP satellite magnetic field model MF6.

Cite this dataset when used as a source.

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Distribution Formats
  • Full Resolution Map (Version: Version 2)
  • Full Resolution Map (Version: Version 2)
  • Full Resolution Map (Version: Version 2)
  • Article (Version: Version 2)
  • Google Earth (Version: Version 2)
  • XYZ/Zip (Version: Version 2)
  • GIS TIFF (Version: Version 2)
  • GMT Grid (Version: Version 2)
  • Color-relief (Version: Version 2)
Distributor DOC/NOAA/NESDIS/NGDC > National Geophysical Data Center, NESDIS, NOAA, U.S. Department of Commerce
Point of Contact NGDC Geomagnetic Modeling Team
DOC/NOAA/NESDIS/NGDC > National Geophysical Data Center, NESDIS, NOAA, U.S. Department of Commerce
geomag.models@noaa.gov
Documentation links not available.
Originator
  • NGDC Geomagnetic Modeling Team
    DOC/NOAA/NESDIS/NGDC > National Geophysical Data Center, NESDIS, NOAA, U.S. Department of Commerce
Publisher
    Publisher information not available.
Date(s)
  • publication: 2009-08-07
Edition: Version 2
Data Presentation Form: mapDigital
Dataset Progress Status Complete
Data Update Frequency: As needed
Purpose: Magnetic anomaly maps provide insight into the subsurface structure and composition of the Earth's crust. Over continental areas, magnetic anomalies illuminate geologic, tectonic, and geothermal evolution of crust and lithosphere. In the world's oceans, anomalies trending parallel to the isochrons (lines of equal age) reveal the temporal evolution of oceanic crust. Magnetic maps are widely used in the geological sciences and in resource exploration.
Use Limitations
  • Cite as: Stefan Maus (2009): EMAG2: Earth Magnetic Anomaly Grid (2-arc-minute resolution). National Geophysical Data Center, NOAA. Model. doi:10.7289/V5MW2F2P [access date]
  • Produced by the NOAA National Geophysical Data Center. Not subject to copyright protection within the United States.
  • Not to be used for navigation. Although these data are of high quality and useful for planning and modeling purposes, they are not suitable for navigation. For navigation, please refer to the NOS nautical chart series.
Time Period: 1946-01-01  to  2008-12-01
Spatial Reference System: urn:ogc:def:crs:EPSG::4326
Spatial Bounding Box Coordinates:
N: 90
S: -90
E: 180
W: -180
Spatial Coverage Map:
Themes
  • EARTH SCIENCE > Solid Earth > Geomagnetism > Magnetic Field
  • EARTH SCIENCE > Solid Earth > Geomagnetism > Magnetic Intensity
  • EARTH SCIENCE > Solid Earth > Geomagnetism > Magnetic Anomalies
Data Centers
  • DOC/NOAA/NESDIS/NGDC > National Geophysical Data Center, NESDIS, NOAA, U.S. Department of Commerce
Places
  • Geographic Region > Global
Use Constraints No constraint information available
Fees Fee information not available.
Lineage Statement Lineage statement not available.
Processing Steps
  • Merged grids at 4 km altitude above geoid using Least Squares Collocation.
  • From all original ship and airborne measurements: subtracted main and external fields given by the Comprehensive Model (Sabaka et al., 2004)
  • Line-leveled the trackline data, minimizing misfits from neighboring and cross-over tracks.
  • Merged the trackline data with the grid at 4 km altitude using Least Squares Collocation with anisotropic correlation function (directional gridding).
  • Substituted spherical harmonic degrees less than or equal to 120 (33 km wavelength) with CHAMP satellite magnetic anomaly model MF6 (Maus et al., 2008).

Metadata Last Modified: 2014-05-29

For questions about the information on this page, please email: Brian.Meyer@noaa.gov