Viscous-type processes in the solar wind-magnetosphere interaction

A debate of long standing concerns the role viscous interactions play in ma gnetospheric dynamics. Is it minor or is it central to, e.g., drive the low latitude boundary layer on closed field lines and account for the substant ial level of wave activity seen on the flanks? Newer data and theoretical c onsiderations leave little doubt that viscous coupling is important. The Ke lvin-Helmholtz instability is a major protagonist in fostering momentum tra nsfer. Closer studies of the state of the flank magnetosphere will help to resolve the issue.