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World Magnetic Model 2020

browse graphicDeclination contour map in miller projection
The World Magnetic Model is the standard model used by the U.S. Department of Defense, the U.K. Ministry of Defence, the North Atlantic Treaty Organization (NATO) and the International Hydrographic Organization (IHO), for navigation, attitude and heading referencing systems using the geomagnetic field. It is also used widely in civilian navigation and heading systems. The model is produced at 5-year intervals, with the current model expiring on December 31, 2024. The current model WMM2020 is produced jointly by the NCEI and the British Geological Survey (BGS). The model, associated software, and documentation are distributed by NCEI on behalf of US National Geospatial-Intelligence Agency and by BGS on behalf of UK Defence Geographic Centre.
  • Cite as: NCEI Geomagnetic Modeling Team; British Geological Survey. 2019: World Magnetic Model 2020. NOAA National Centers for Environmental Information. https://doi.org/10.25921/11v3-da71. Accessed [date].
gov.noaa.ngdc:WMM2020
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Distribution Formats
    Ordering InstructionsContact NCEI for other distribution options and instructions.
    DistributorNOAA National Centers for Environmental Information
    ncei.info@noaa.gov
    Dataset Point of Contact NOAA National Centers for Environmental Information
    ncei.info@noaa.gov
    Dataset Point of Contact NCEI Geomagnetic Modeling Team
    NOAA National Centers for Environmental Information
    geomag.models@noaa.gov
    Time Period2020-01-01 to 2024-12-31
    Spatial Reference Systemurn:ogc:def:crs:EPSG::4326
    Spatial Bounding Box Coordinates
    N: 90
    S: -90
    E: 180
    W: -180
    Spatial Coverage Map
    General Documentation
    Publication Dates
    • publication: 2019-12-10
    Edition1
    Data Presentation FormmapDigital
    Dataset Progress StatusComplete - production of the data has been completed
    Historical archive - data has been stored in an offline storage facility
    Data Update Frequency As needed - Associated WMM2020 software may be updated as improvements are created.
    PurposePurpose statement not available
    Use Limitations
    • Produced by the NOAA National Centers for Environmental Information. Not subject to copyright protection within the United States.
    Dataset Citation
    • Cite as: NCEI Geomagnetic Modeling Team; British Geological Survey. 2019: World Magnetic Model 2020. NOAA National Centers for Environmental Information. https://doi.org/10.25921/11v3-da71. Accessed [date].
    Cited Authors
    • NCEI Geomagnetic Modeling Team
    • British Geological Survey Geomagnetism Team
      British Geological Survey
    Publishers
    • NOAA National Centers for Environmental Information
    Theme keywordsGlobal 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 Declination
    • Earth Science > Solid Earth > Geomagnetism > Magnetic Inclination
    Data Center keywordsGlobal 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 keywordsGlobal Change Master Directory (GCMD) Location Keywords
    • Geographic Region > Global
    Use Constraints
    • Use liability: NOAA and NCEI cannot provide any warranty as to the accuracy, reliability, or completeness of furnished data. Users assume responsibility to determine the usability of these data. The user is responsible for the results of any application of this data for other than its intended purpose.
    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.
    Other ConstraintsCite as: NCEI Geomagnetic Modeling Team; British Geological Survey. 2019: World Magnetic Model 2020. NOAA National Centers for Environmental Information. https://doi.org/10.25921/11v3-da71. Accessed [date].
    Fees
    • WMM2020 and associated softwares are all free and publically available
    Lineage information for: dataset
    Processor
    • NOAA National Centers for Environmental Information
    • NOAA National Centers for Environmental Information
    • NOAA National Centers for Environmental Information
    Processing Steps
    • Measurements during daytime and during periods of strong solar activity are contaminated by external current systems, which are difficult to accurately model. Therefore, only nighttime data during magnetically quiet periods were used in generating the WMM coefficients.
    • Some contributions to the measured magnetic field, such as the diamagnetic effect of ionospheric plasma (Lühr et al, 2003) or motional induction by tidal ocean currents (Kuvshinov and Olsen, 2005; Maus, 2007), can be accurately modeled and were corrected for prior to the generation of the WMM main field coefficients.
    • To account for the contributions that have not been removed in the previous steps, an extended set of model parameters is co-estimated with the WMM model coefficients. These account for smaller-wavelength internal magnetic field contributions (spherical harmonic degree larger than 12), second time derivatives (secular acceleration) and contributions from currents external to the Earth. The set of WMM coefficients plus the extended model parameters is called a parent model of the WMM. Two different parent models were produced, reflecting different modeling strategies employed by NGDC for the main field model and BGS for the secular variation model.
    Source Datasets
    • Swarm Satellite Data
    • INTERMAGNET Observatory Data
    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.
    Last Modified: 2020-05-14
    For questions about the information on this page, please email: ncei.info@noaa.gov