The isentropic transport of a passive tracer on synoptic time scales in the winter lower stratosphere is modeled with the use of a high-resolution transport model, which is forced by winds derived from global meteorological analyses. The study has focused on a meteorological situation which occurred in late January 1992. Repeated poleward intrusions of mid-latitude air are shown to lead to the filamentation of a tracer distribution, which was initially compact and located inside the polar vortex. The effect of wind resolution on the filamentation process is examined. By performing isentropic advection on many closely space independent levels the vertical structure of these filaments can be studied. ¿American Geophysical Union 1995