Geomagnetic indices

The International Service of Geomagnetic Indices (ISGI) is in charge of the elaboration and dissemination of geomagnetic indices, and of tables of remarkable magnetic events, based on the report of magnetic observatories distributed all over the planet, with the help of ISGI Collaborating Institutes (EOST, GFZ, WDC, AARI, DTU and Ebre observatory).
The interaction between the solar wind, including plasma and interplanetary magnetic field, and the Earth's magnetosphere results in a transfer of energy and particles inside the magnetosphere. Solar wind characteristics are highly variable, they have actually a direct influence on the shape and size of the magnetosphere, on the amount of transferred energy, and on the way, this energy is dissipated.
Geomagnetic indices aim at describing the geomagnetic activity or some of its components. Each geomagnetic index is related to different phenomena occurring in the magnetosphere, ionosphere and in the Earth deep. The location and timing of a measurement and the way the index is calculated depend on the related phenomenon.

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