Geophysical surveys

, Volume 6, Issue 3–4, pp 439–456 | Cite as

The generation ofK indices from digitally recorded magnetic data

  • J. C. Riddick
  • W. F. Stuart


TheK index was developed by Bartels and is a measure of geomagnetic activity. The important feature of this index is that it is a measure of solar activity superimposed on the regular daily variation.

It is the most used estimate of activity being of particular interest to researchers in ionospheric physics and telecommunications.

In response to increased availability of digital data from magnetic observatories and their demand by the scientific community it becomes desireable to check whetherK indices produced from magnetograms plotted from digital data are consistent with those handscaled from La Cour charts.

This paper presents results of these comparisons and also reports on several methods tested to produce theK index directly from the digital data.

Handscaled indices from digital plots are suitable for producing theK index. Computations using digital data do not reproduceK as defined by Bartels precisely but do provide an equivalent index which is satisfactory for most user and research purposes.


Scientific Community Solar Activity Research Purpose Daily Variation Digital Data 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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Copyright information

© D. Reidel Publishing Company 1984

Authors and Affiliations

  • J. C. Riddick
    • 1
  • W. F. Stuart
    • 1
  1. 1.Geomagnetism Research GroupBritish Geological SurveyEdinburgh

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