TOWARD A CLOSER INTEGRATION OF MAGNETOSPHERIC RESEARCH - MAGNETOSPHERIC CURRENTS INFERRED FROM GROUND-BASED MAGNETIC DATA

A new approach is needed to advance magnetospheric physics in the futu re to achieve a much closer integration than in the past among satelli te-based researchers, ground-based researchers, and theorists/modelers . Specifically, we must find efficient ways to combine two-dimensional ground-based data and single points satellite-based data to infer thr ee-dimensional aspects of magnetospheric disturbances. For this partic ular integration purpose, we propose a new project. It is designed to determine the currents on the magnetospheric equatorial plane from the ionospheric current distribution which has become available by invert ing ground-based magnetic data from an extensive, systematic network o f observations, combined with ground-based radar measurements of ionos pheric parameters, and satellite observations of auroras, electric fie lds, and currents. The inversion method is. based on the KRM/AMIE algo rithms. In the first part of the paper, we extensively review the reli ability and accuracy of the KRM and AMIE algorithms and conclude that the ionospheric quantities thus obtained are accurate enough for the n ext step. In the second part, the ionospheric current distribution thu s obtained is projected onto the equatorial plane. This process requir es a close cooperation with modelers in determining an accurate config uration of the magnetospheric field lines. If we succeed in this proje ction, we should be able to study the changing distribution of the cur rents in a vast region of the magnetospheric equatorial plane for exte nded periods with a time resolution of about 5 min. This process requi res a model of the magnetosphere for the different phases of the magne tospheric substorm. Satellite-based observations are needed to calibra te the projection results. Agreements and disagreements thus, obtained will be crucial for theoretical studies of magnetospheric plasma conv ection and dynamics, particularly in studying substorms. Nothing is ea sy in these procedures. However, unless we can overcome the associated difficulties, we may not be able to make distinct progresses. We beli eve that the proposed project is one way to draw the three groups clos er together in advancing magnetospheric physics in the future. It is i mportant to note that the proposed project has become possible because ground-based space physics has made a major advance during the last d ecade.