The generation ofK indices from digitally recorded magnetic data
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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.
KeywordsScientific Community Solar Activity Research Purpose Daily Variation Digital Data
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- Bartels, J., Heck, N. H., and Johnston, H. F.: 1939, ‘Three Hour-range Index Measuring Geomagnetic Activity’,Terr. Magn. Atmos. Electricity.Google Scholar
- Chapman, S. and Bartels, J.: 1940,Geomagnetism, Oxford University Press.Google Scholar
- Forbes, A. J. and Riddick, J. C.: 1984, ‘The Digital Recording System operated at the U.K. Observatories’,Geophysical Surveys 6, 393–405 (this issue).Google Scholar
- Loomer, E. I., Janson Van Beck, G., and Niblett, E. R.: 1983,Derivations of K-indices Using Magnetograms Constructed from Digital Data, IAGA News No. 22.Google Scholar
- Mayaud, P. N.: 1980, ‘Derivation, Meaning and Use of Geomagnetic Indices’,Geophysical Monograph 22, American Geophysical Union.Google Scholar
- Mills, P. M., Dyson, K., Green, C. A., and Stuart, W. F.: 1976, The Data Transcription and Retrieval System used for Cassette Recording of the I.G.S. Rubidium Magnetometers,Geomagnetism Unit Report No. 20.Google Scholar
- Riddick, J. C., Forbes, A. J., and Green, C. A.: 1981, ‘The Recording and Processing of Digital Magnetic Data from the U.K. Observatories’,Geomagnetism Unit Report No. 27.Google Scholar
- Stuart, W. F., Dyson, K., and Mackintosh, S. M.: 1969, ‘The Use of Semi-automatic Scaling Methods in Observatory Geomagnetism’,Geomagnetism Unit Report No. 4.Google Scholar