Space scientists have a wide variety of models to choose from for their studies of the Earth's auroral phenomenon, radiation belts, magnetotail, magnetopause, etc. Different types of models are suited for different purposes. At his time, there is no one model to suit everyone's needs. In this paper a general overview of magnetospheric modeling is given, along with a more detailed discussion of several empirical models which are widely used. These models are composed of representations of the Earth's main internal field (basically a dipolar field), plus external field contributions due to ring currents (carried by the particles in the Van Allen radiation belts), magnetopause currents (the boundary surface between the Earth's magnetic field and the interplanetary magnetic field carried by the solar wind), and tail currents (carried by particles in the neutral sheet of the magnetotail). As in many disciplines, models are frequently chosen for convenience rather than for their intrinsic properties. Here a summary of the properties of the most commonly used models is given. discussion of MHD models is beyond the scope of this paper.

The empirical models presented here are the Mead-Fairfield, Olson-Pfitzer tilt-dependent (1977), Tsyganenko-Usmanov, Tsyganenko (1987), Olson-Pfitzer dynamic (1988), Tsyganenko (1989), and Hilmer-Voigt models. The derivations, agreement with quiet time and storm time data from the two satellite programs SCATHA and CRRES, and computation requirements of these models are compared. ¿ American Geophysical Union 1994