The evolution of trailing plumes from active regions

We have studied the evolution of several high-latitude flux 'plumes', i.e., unipolar regions, trailing from active regions which emerged near sunspot maximum in cycle 23. The observed patterns are compared with simulations us ing a simple flux transport equation based on the observed flux for an earl ier Carrington rotation. In addition to the long recognized poleward migrat ion and diffusion of flux from active regions, it is found that the evoluti on of the trailing plumes may be influenced by flux which emerges above lat itude 35 degrees over areas of all scales. We describe two cases in which t he emerging flux appears in the form of bipolar flux patterns which are not obviously related to sunspots. Further, we find instances in which the obs erved surface flux decreases or spreads at rates which cannot be explained solely in terms of diffusion using the normally accepted rates. Thus in sev eral cases the poleward migration of flux cannot be described in terms of p assive transport by advection and diffusion as considered here, and further investigation of the processes that contribute to the evolution of the pol ar fields is required.