Data Formats

The INTERMAGNET Operations Committee defines and publishes data formats for use by INTERMAGNET participants. The data produced by INTERMAGNET will use one of these formats:

Due to the method that is used to record geomagnetic data it is not possible to make continuous measurements of the absolute value of the Earth's magnetic field. Instead a continuous record of variations in the field is made automatically, usually using computer controlled instrumentation. These data are made available as a preliminary data set, called reported data. The first operation that occurs on the data is the removal of any contamination (such as might be caused by instrumentation faults or man-made interference). The resulting data set is called adjusted data. This is then combined with a baseline that has been calculated from regular spot-values of the absolute field, which are made periodically using manual observation techniques. The combined data set, called definitive data, is a record of the absolute value of the field, but it is not made available until some time after the event (typically a few months after the end of each year).

In order to satisfy the requirements for both faster and more accurate data, INTERMAGNET has created two separate services for data dissemination. The INTERMAGNET CD-ROM/DVD is published annually and contains definitive data from all participating observatories. The Geomagnetic Information Nodes (GINs) provide an on-line repository for reported and adjusted data. Data are sent from the participating observatories to the GIN within 72 hours of recording. They are then held on-line until the annual CD-ROM/DVD is available.