The physics and meaning of the existing and proposed high-latitude geomagnetic indices

The success and failures of existing indices of high-latitude geomagnetic activity are examined. It is shown that AU, AL and AE-indices are only approximate characteristics of the magnetic activity in the auroral zone, and their physical meaning is not sufficiently large. The improvement could be made by an introduction of some other characteristics with more definite physical sense, such as the PC index displaying the solar wind electric field penetrating into the magnetosphere, and some local auroral zone characteristics showing the structure of the auroral electrojets.