A new computational method for rapid estimation of the K-index
Shingo NAGAMACHI
Abstract
 We have developed a new computational method for estimating the K-index. This method represents the quiet-day pattern of geomagnetic variation by a polygonal curve with inflection points at intervals of one hour. The accuracy of this new method is higher than that of the Linear-phase Robust Non-linear Smoothing (LRNS) method; in particular, we have obtained good results for the K>5 threat score. By using this method, we have begun to upload rapid geomagnetic activity estimates onto the website of the Kakioka Magnetic Observatory.