Data on the Earth's Magnetic Field and its Secular Change since 1800

Information on the past and present orientation of the Earth's magnetic field is available from the National Geophysical Data Center (NGDC) which serves as the national data bank for geomagnetic data. The Earth's magnetic field has been measured by land surveys, ships, aircraft and satellites at hundreds of locations resulting in millions of observations. Many of the observations are of poor quality or are unevenly distributed around the globe. Because of these limiting factors and the variation of the main magnetic field with time, the Earth's field is usually approximated by mathematical models. These models, adjusted to fit selected available observations, have wide application in geophysical and space sciences. Surveyors can obtain data and information for individual specific locations worldwide. Past values of the magnetic field are available from models for areas within the conterminous U.S. from 1750 or from 1945 worldwide. These mathematical models must be periodically updated due to the changing nature of the Earth's magnetic field. NGDC maintains the models and data base of observations to track secular variation of the Earth's magnetic field. Models and software are available on-line. The global geomagnetic observations data bases for secular change studies include high-quality magnetic observations made at observatories worldwide since 1800. Other geomagnetic data bases are: IAGA Repeat Station data base which contains observations from exact reoccupations, Other land Surveys containing miscellaneous land observations worldwide since 1800 including a few thousand observations made at sea by the non-magnetic ships, Carnegie and Zarya, Vector airborne surveys from the Project Magnetic aircraft, satellite and selected marine observations. Most of the surface data are available on-line. At most locations, three magnetic elements were observed: Either declination (D), Inclination (I), and horizontal intensity (H), or declination, horizontal intensity, and vertical intensity (Z), or total intensity (F). Where possible, the values for other magnetic elements, usually the north component (X) and east component (Y), were derived by the computer. The altitude, latitude, and longitude are recorded for each observation. The observatory annual means file contains the results of more of the observatories operating since 1800. Files are revised as new data become available. Searches and plots of data from selected stations can be made. These secular change files are the principal source for tracking the long-period changes in the direction and intensity of the Earth's magnetic field. Other data include a digital bibliography of historical magnetic survey publications at NGDC and the co-located World Data Center-A. Over 750 reports published from the 1830's to 1980's were inventoried in a digital bibliography and digitally imaged in .PCX format. The digital images of these reports have been written to magnetic tape.
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  • TIFF
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DOC/NOAA/NESDIS/NCEI > National Centers for Environmental Information, NESDIS, NOAA, U.S. Department of Commerce
Dataset No POCs available for this dataset
Time Period 1800-01-01 to Present
Spatial Bounding Box Coordinates
N: 90.00
S: -90.00
E: 180.00
W: -180.00
Spatial Coverage Map
General Documentation
Publication Dates
  • publication: 1972-01-01
Edition First
Dataset Progress Status Under development - data is currently in the process of being created
Data Update Frequency Annually
Supplemental Information
Formally FE 17, 119, 626
Purpose Provide information for research and surveyors
  • DOC/NOAA/NESDIS/NCEI > National Centers for Environmental Information, NESDIS, NOAA, U.S. Department of Commerce
  • DOC/NOAA/NESDIS/NCEI > National Centers for Environmental Information, NESDIS, NOAA, U.S. Department of Commerce
  • 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>Geomagnetic Forecasts
  • EARTH SCIENCE>SOLID EARTH>Geomagnetism>Geomagnetic Indices
  • EARTH SCIENCE>SOLID EARTH>Geomagnetism>Geomagnetic Induction
  • EARTH SCIENCE>SOLID EARTH>Geomagnetism>Magnetic Anomalies
  • EARTH SCIENCE>SOLID EARTH>Geomagnetism>Magnetic Declination
  • EARTH SCIENCE>SOLID EARTH>Geomagnetism>Magnetic Inclination
  • EARTH SCIENCE>SOLID EARTH>Geomagnetism>Magnetic Intensity
  • EARTH SCIENCE>SOLID EARTH>Geomagnetism>Paleomagnetism
  • EARTH SCIENCE>SOLID EARTH>Geomagnetism>Reference Fields
Uncontrolled Keywords
  • Secular Change
  • Magnetic Observatory
  • Magnetic Models
  • Magnetic Survey
  • Magnetospheric Science
Place keywords Global Change Master Directory (GCMD) Location Keywords
  • Global
Project keywords Global Change Master Directory (GCMD) Project Keywords
  • ICSU-WDS > International Council for Science - World Data System
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    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: 2017-09-25
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