Surface Geomagnetic Data and Information

Historically, magnetic observatories were established to monitor the secular change of the Earth's magnetic field, and this remains one of their most important functions. This generally involves absolute measurements sufficient in number to monitor instrumental drift and to produce annual means. Over 70 countries operate more than 200 observatories worldwide. The magnetic observatory data are crucial to the studies of secular change, investigations into the Earth's interior, navigation, communication, and to global modeling efforts. Please send additions, corrections and comments to Susan McLean

In addition to the continuously operating magnetic observatories, many countries make measurements at temporary magnetic stations over a period of days every 5 - 10 years. Many of the observations are available for download. A listing of repeat station data is available.

• Observatory Annual Means - This link is temporarily disabled while we improve our data connection. Please accept our apologies for any inconvenience.
• Contact Information in html format
• Observatory 1-minute and Hourly Mean Data
• Marine magnetic data
• Many magnetic indices are available on-line
• An example of some of the older observatory data available from NGDC / WDC, Boulder.