STEREO. SECCHI - Solar Physics Branch - Naval Research Laboratory. Geomagnetic storm severity info (K-Index) NOAA / Space Weather Prediction Center The K-index is a code that is related to the maximum fluctuations of horizontal components observed on a magnetometer relative to a quiet day, during a three-hour interval.
The conversion table from maximum fluctuation (nT) to K-index, varies from observatory to observatory in such a way that the historical rate of occurrence of certain levels of K are about the same at all observatories. In practice this means that observatories at higher geomagnetic latitude require higher levels of fluctuation for a given K-index. The conversion table for the Boulder magnetometer is shown below: Helioviewer - Solar and heliospheric image visualization tool. SolarBeat. NOAA / NWS Space Weather Prediction Center. SOLARCYCLE 24.com / SolarHam.com / Solar Cycle 24 / Spaceweather / Amateur Radio VHF Aurora Website / Sunspots / Solar Flares. Aurora Watch - Home. Solar and Heliospheric Observatory Homepage.