National Geophysical Data Center (NGDC), NOAA Satellite and Information Service

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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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Distribution Formats
  • TIFF
Distributor Distributor information not available
Point of Contact Susan McLean
DOC/NOAA/NESDIS/NCEI > National Centers for Environmental Information, NESDIS, NOAA, U.S. Department of Commerce
(303) 497-6478
General Documentation
  • Dataset contact information not available
  • publication: 1972-01-01
Edition: First
Dataset Progress Status Under development
Data Update Frequency: Annually
Supplemental Information: Formally FE 17, 119, 626
Purpose: Provide information for research and surveyors
Use Limitations
  • While every effort has been made to ensure that these data are accurate and reliable within the limits of the current state of the art, NOAA cannot assume liability for any damages caused by any errors or omissions in the data, nor as a result of the failure of the data to function on a particular system. NOAA makes no warranty, expressed or implied, nor does the fact of distribution constitute such a warranty.
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:
  • 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
  • Secular Change
  • Magnetic Observatory
  • Magnetic Models
  • Magnetic Survey
  • Magnetospheric Science
Data Centers
  • 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
  • Global
Use Constraints
  • Use Constraints: None
Access Constraints
  • Access Constraints: No Constraints
  • Depends on the Data Set
Lineage Statement Lineage statement not available.

Metadata Last Modified: 2015-09-01

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