The planetary Kp-index index is determined from the data of 12 geomagnetic observatories located in the northern and southern hemispheres of the Earth. For the purposes of prevention and early warning of the interested authorities and the society, methods are used to determine the approximate value of the index, ie. of the disturbance of the earth’s magnetic field at any given moment. It is given in relative units, ranging from 0 to 9 depending on the field disturbance.

Kp-индекс за България Fig.1 Geomagnetic forecast

Information on the current Kp-index can be found here.


Because anomalies in the Earth’s magnetic field are caused by the solar wind it is possible to determine the degree of disturbance of the Earth’s magnetic field based on its parameters. This is possible due to the availability of current data received from a stationary satellite outside the Earth’s atmosphere – Advanced Composition Explorer (ACE). The methodology developed by the staff of the NIGGG – BAS makes it possible to calculate an approximate estimate of the Kp index called Kpm based on these data, which is available every 15 minutes and is automatically published. The confidence interval for this value with a probability of 50% is 0.63. A prognostic value for the 6 hours following any current moment is also published. The forecast is calculated based on the behavior of the geomagnetic activity over the past two days following the Wiener-Hopf method.