Earth's magnetic field live

The magnetic field seen from the ground

The Chambon-la-Forêt observatory, south of Paris, has measured the Earth's magnetic field since 1936 for the Institut de physique du globe de Paris. Its magnetometers record every minute the three components of the field, X northward, Y eastward, Z downward, and its total intensity F, a little over 48,000 nanoteslas in France.

Through a quiet day the field undulates by a few tens of nanoteslas under the electric currents of the ionosphere heated by the Sun. During a geomagnetic storm it swings by several hundred nanoteslas within minutes: that agitation, measured at thirteen observatories of the same INTERMAGNET network, is what the Kp index is computed from.

The same storms disturb the ionosphere and hence the Schumann resonance; the Kp page gives the planetary summary, this one the local detail.