Why Geosynchronous Orbit?
It is difficult to present mapping comparisons for 6 models over a large range of L-shells so we have concentrated on geosynchronous orbit at 6.6 Re. Geosynchronous orbit is interesting because it lies in a transition region where both internal and external magnetic field contributions are important and because many important substorm processes are observed there. Indeed many of us now suspect that the substorm onset mechanism may actually be found near geosynchronous orbit. One reason for this suspicion comes from the magnetic field models themselves. As the figures in this paper show geosynchronous orbit typically maps to an oval which looks essentially identical to the auroral oval. Another reason for choosing geosynchronous orbit is that it supports another area of research which we are pursuing. Using Magnetospheric Plasma Analyzer (MPA) data from two geosynchronous spacecraft and data from the plasma analyzers on three low-altitude DMSP spacecraft we are testing the mapping betwe
