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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.
Download Data
  • EMAG2 Full Resolution Map poster (download)
    PDF of Full Resolution Map of EMAG2 as a poster
  • EMAG2 Full Resolution Map poster (download)
    JPG of Full Resolution Map of EMAG2 as a poster.
  • EMAG2 Full Resolution Map image (download)
    JPG of Full Resolution Map of EMAG2 as an image.
  • EMAG2: A 2-arc-minute resolution Earth Magnetic Anomaly Grid compiled from satellite, airborne and marine magnetic measurements (download)
    Preprint of manuscript "EMAG2: A 2-arc-minute resolution Earth Magnetic Anomaly Grid compiled from satellite, airborne and marine magnetic measurements", submitted for publication to Geochem. Geophys. Geosyst.
  • Google Earth (download)
    Plugin for Google Earth. Requires installation of Google Earth.
  • XYZ/Zip (download)
    EMAG2 ASCII grid of the magnetic total intensity at 4km above WGS84 ellipsoid.
  • GIS TIFF (download)
    A georeferenced TIFF (GeoTIFF) with a resolution of 2-arc-minutes, which can be opened by ESRI ArcGIS or any other GIS application. The values (nT) are stored as 32-bit floating point.
  • GMT Grid (download)
    A GMT (Generic Mapping Tools) compatible netCDF grid with resolution of 2-arc-minutes. The values (nT) are stored as 32-bit floating point.
  • Color-relief (download)
    A 24-bit RGB georeferenced TIFF (GeoTIFF) color-relief visualization of the EMAG2 grid, which can be opened by ArcGIS or any other GIS application.
  • XYZ/zip (download)
    EMAG2 (Version 2.0) ASCII grid of the magnetic total intensity at 4km above WGS84 ellipsoid. This version was produced without directional gridding. Therefore, it has much sparser coverage but reflects more closely the actual measurements.
Distribution Formats
  • Full Resolution Map (Version: Version 2)
    • File Specification: PDF of EMAG2 as a poster
  • Full Resolution Map (Version: Version 2)
    • File Specification: JPG of EMAG2 as a poster
  • Full Resolution Map (Version: Version 2)
    • File Specification: JPG of EMAG2 as an image
  • Article (Version: Version 2)
    • File Specification: Preprint of manuscript "EMAG2: A 2-arc-minute resolution Earth Magnetic Anomaly Grid compiled from satellite, airborne and marine magnetic measurements", submitted for publication to Geochem. Geophys. Geosyst.
  • Google Earth (Version: Version 2)
    • File Specification: Plugin for Google Earth. Requires installation of Google Earth. See also https://productforums.google.com/forum/?fromgroups#!msg/gec-dynamic-data-layers/yYsaTFnIzYQ/RVwprs5WhPQJ[1-25]
  • XYZ/Zip (Version: Version 2)
    • File Specification: ASCII grid of the magnetic total intensity at 4km above WGS84 ellipsoid.
  • GIS TIFF (Version: Version 2)
    • File Specification: A georeferenced TIFF (GeoTIFF) with a resolution of 2 arc-minutes, which can be opened by ESRI ArcGIS or any other GIS application. The values (nT) are stored as 32-bit floating point.
  • GMT Grid (Version: Version 2)
    • File Specification: A GMT (Generic Mapping Tools) compatible net CDF grid with resolution of 2-arc-minutes. The values (nT) are stored as 32-bit floating point.
  • Color-relief (Version: Version 2)
    • File Specification: A 24-bit RGB georeferenced TIFF (GeoTIFF) color-relief visualization of the EMAG2 grid, which can be opened by ArcGIS or any other GIS application. The color scale legend is at http://geomag.colorado.edu/images/EMAG2_scale.png
Distributor DOC/NOAA/NESDIS/NCEI > National Centers for Environmental Information, NESDIS, NOAA, U.S. Department of Commerce
Dataset Point of Contact NCEI Geomagnetic Modeling Team
DOC/NOAA/NESDIS/NCEI > National Centers for Environmental Information, NESDIS, NOAA, U.S. Department of Commerce
geomag.models@noaa.gov
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
Documentation links not available.
Publication Dates
  • publication: 2009-08-07
Edition Version 2
Data Presentation Form mapDigital
Dataset Progress Status Complete - production of the data has been completed
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.
Originators
  • DOC/NOAA/NESDIS/NGDC > National Geophysical Data Center, NESDIS, NOAA, U.S. Department of Commerce
Distributors
  • DOC/NOAA/NESDIS/NCEI > National Centers for Environmental Information, NESDIS, NOAA, U.S. Department of Commerce
Points of Contact
  • DOC/NOAA/NESDIS/NCEI > National Centers for Environmental Information, NESDIS, NOAA, U.S. Department of Commerce
Publishers
  • DOC/NOAA/NESDIS/NCEI > National Centers for Environmental Information, NESDIS, NOAA, U.S. Department of Commerce
Theme keywords Global Change Master Directory (GCMD) Science Keywords
  • EARTH SCIENCE > Solid Earth > Geomagnetism > Magnetic Field
  • EARTH SCIENCE > Solid Earth > Geomagnetism > Magnetic Intensity
  • EARTH SCIENCE > Solid Earth > Geomagnetism > Magnetic Anomalies
Data Center keywords Global Change Master Directory (GCMD) Data Center Keywords
  • DOC/NOAA/NESDIS/NCEI > National Centers for Environmental Information, NESDIS, NOAA, U.S. Department of Commerce
  • DOC/NOAA/NESDIS/NGDC > National Geophysical Data Center, NESDIS, NOAA, U.S. Department of Commerce
Place keywords Global Change Master Directory (GCMD) Location Keywords
  • Geographic Region > Global
Use Constraints No constraint information available
Access Constraints
  • Distribution liability: NOAA and NCEI make no warranty, expressed or implied, regarding these data, nor does the fact of distribution constitute such a warranty. NOAA and NCEI cannot assume liability for any damages caused by any errors or omissions in these data. If appropriate, NCEI can only certify that the data it distributes are an authentic copy of the records that were accepted for inclusion in the NCEI archives.
Fees Fee information not available.
Lineage information for: repository
Processing Steps
  • 2015-04-22T00:00:00 - NOAA created the National Centers for Environmental Information (NCEI) by merging NOAA's National Climatic Data Center (NCDC), National Geophysical Data Center (NGDC), and National Oceanographic Data Center (NODC), including the National Coastal Data Development Center (NCDDC), per the Consolidated and Further Continuing Appropriations Act, 2015, Public Law 113-235. NCEI launched publicly on April 22, 2015.
Lineage information for: model
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).
Last Modified: 2015-08-31