The Kp-index
The Kp-index is the global geomagnetic storm index and is based on 3h measurements of the K-indices, for a given value, for each of the past days. The Kp plot on this website shows you the Kp-indices of the past 24 hours and a forecast of the hour to come. This plot gives you an immediate idea how good the chances are on this moment and what the global activity was the past day. In the Kp-index we can classify these into four categories:
| Active | K=4 |
| Minor storm | K=5 |
| Major storm | K>6 |
| Extreme storm | K=9 |
The K-index itself is a three hour long logoritmic local index of the geomagnetic activity,
relative to a calm day curve for the given location. The Kp-index has a scale of 0 till 9.
When you live in the high latitudes a Kp index of 3-4 could be enough but in the Middle Latitudes
(depending on the precise location) a Kp index of 7 till 8 is required; the low latitudes must have
a Kp index of 9.
The Kp-index measures the deviation of the most disturbed horizontal component of the magnetic field
on fixed stations worldwide with their own local K-index. Those measuremunts put together with a good
algorithm, that puts the averages of every station together, gives us the global Kp index.