Recent improvements in the numerical scheme of estimating field-aligned current systems from ground magnetometer records

The capability of ground-based magnetometer data of estimating field-aligned current systems is discussed. Starting with some basic equations governing electrodynamic parameters in the ionosphere, this paper describes both the advantages and limitations of the algorithms known as magnetogram-inversion techniques, as well as the results of recent efforts to improve the scheme so that several different types of measurements using satellites and radars can be incorporated