Abstract
The method used for estimating the daily regular variation of the magnetic field and the computation of digital K values are discussed. Test magnetograms, synthesized from digital one-minute values for a wide range of magnetic conditions, are shown with regular variation curves superimposed on their respective component traces. Comparisons of K-indices computed from digital one minute values with K-indices handscaled from magnetograms were made using data from five U. S. Geological Survey magnetic observatories. The test magnetograms and normal magnetograms were examined to identify possible sources of difference in the two methods. The results indicate that the number of differences attributed to bias in the digital method may not be significantly different than the number of subjective differences by the handscaling method.
