Can Kelvin-Helmholtz instabilities of jet-like structures and plumes causesolar wind fluctuations at 1 AU?

The long high-latitude sampling of Ulysses provides the opportunity to stud y fine structures. At latitudes poleward of similar to -60 degrees the sola r wind had fluctuations in velocity gradients which were attributed to "mic rostreams." The data also suggested fluctuations characterized by magnetic plus thermal pressure balance structures ('PBS'). At higher frequencies, MH D turbulence was observed and found to be less evolved than it is in the ec liptic but essentially independent of heliographic latitude. It is argued h ere that microstreams, PBS, and MHD turbulence could all be the remnants of mixing due to sheer instabilities associated with plumes and other filamen tary structures ("jets") in coronal holes. To show this, we simulate a plum e-like jet in the presence of an ambient magnetic field. We find that the p resence of the ambient field reduces the growth rate of the instability, bu t the shear between a jet and its ambient still becomes unstable to the MHD Kelvin-Helmholtz instability when the shear speed is larger than the large st local magnetosonic speed, a condition probably satisfied for plumes.