ANOMALOUS TRANSPORT BY MAGNETOHYDRODYNAMIC KELVIN-HELMHOLTZ INSTABILITIES IN THE SOLAR-WIND MAGNETOSPHERE INTERACTION

A magnetohydrodynamic simulation of Kelvin-Helmholtz instabilities in a compressible plasma has been performed for parallel and transverse configurations, modeling high-latitude (or downstream flanks) and dayside low-latitude magnetospheric boundaries. Although this simulation model is rather simple, the results obtained illuminate the nature of the anomalous transport and show that the MHD Kelvin-Helmholtz instabilities are quite different for the two distinct configurations of flow and magnetic field that have been considered. In the transverse configuration the viscous interaction is due to the hydrodynamic Reynolds stress. If it is applied to the low-latitude boundary, it could account for a convection potential drop over the polar cap of approximately 10-30 kv. But where the configuration involves the magnetic field parallel to the shear flow, the viscous interaction is essentially due to the hydromagnetic Maxwell (magnetic) stress, which gives rise to transport 2-3 times larger than that in the transverse configuration.