The external magnetic sources over the polar caps - Feasible modelling unrealistic expectations

Abstract

No average status can be defined for the sources of the external magnetic field over the polar caps, no index can provide with any such model, the observation of no single quantity or parameter can give the ultimate solution. Rather, every case history has to be considered independently. It is possible, however, to approach the problem from an interdisciplinary viewpoint, and to attempt to make an instant modelling of the electric currents that flow in the ionosphere and magnetosphere above the area of aeromagnetic prospecting. A few relevant previous such examples are discussed (such as Akasofu's inference on magnetospheric substorms derived by means of polar auroras, or the presently unfashionable Svalgaard vortex by means of the observed geomagnetic field and dealing with the pattern of the electric field within the magnetosphere, or the Sun-aligned auroral arcs inside the oval that are monitored by satellite, or, perhaps, the luminosity curve of polar auroras). It appears likely that some substantial achievement will be attained altogether with the progress in the understanding of the general pattern of a few typical recurrent configurations over the polar caps, in terms of a multidisciplinary input from different observations, either by ground-based observatories, or by space platforms.