The Contribution of a Geophysical Data Service: The International Service of Geomagnetic Indices

Geomagnetic indices are basic data in Solar-Terrestrial physics, and for operational Space Weather activities. The International Service of Geomagnetic Indices (ISGI) is in charge of the derivation and dissemination of geomagnetic indices that are acknowledged by the International Association of Geomagnetism and Aeronomy (IAGA, an IUGG association). Institutes which are not part of ISGI started early in the internet age to circulate on-line preliminary values of geomagnetic indices. In absence of quality stamping, this resulted in a very confusing situation. The ISGI label was found to be the simplest and the safest way to insure quality stamping of circulated geomagnetic indices.