MULTISCALE COUPLING IN PLANETARY MAGNETOSPHERES

Processes in planetary magnetospheres occur on a variety of scales. On the largest scales are the plasma circulations induced in the magnetospheric plasma externally by the solar wind interaction or internally by processes such as massloading of the jovian magnetosphere by the moon Io. These large-scale processes are influenced by small-scale processes such as particle scattering by waves, gyro motion, and charge exchange. It is not always clear which of two coupled processes are in control. For example, many believe that the onset of reconnection requires a microscale instability but it is possible that external forcing leads to the magnetic configuration at which reconnection eventually occurs, and it is only the existence of the appropriate magnetic configuration over a sufficiently large region that is required to cause the macroscopic flows. This paper reviews such coupling in the magnetospheres of the Earth and Jupiter