Yesterday, today and tomorrow of geomagnetic indices
地磁活动指数的过去、现在和未来

Geomagnetic disturbances, or activities, are extremely complicated phenomena with broad aspects, multiple components, different morphology, wide spectra, and complicated mechanisms. It is certainly necessary to physically study each of the disturbances. However, it has proved very valuable to derive various indices on the basis of local disturbances at many individual stations, although some of them take little or no account of the structure of the disturbance field and its mechanisms. Many magnetic observatories throughout the world send their local indices to an international center at De Bilt in the Netherlands, which is linked with the Permanent Service of Geomagnetic indices at Gottingen, Germany. There the local indices are used as the basis for world indices. The indices have been applied with great success not only in the geomagnetism, but also in related fields, such as solar-terrestrial coupling, cosmic rays, and space weather prediction. In this paper about 50 magnetic indices are reviewed in two groups, respectively for the overall activity level and certain kind of disturbances. A brief overview on the history of magnetic indices, merits and drawbacks, and future perspective is given.