The global pattern of evolution of plasmaspheric drainage plumes J. Goldstein and B. R. Sandel We present observations of an 18 June 2001 erosion event obtained by the IMAGE extreme ultraviolet (EUV) imager. Following a 0304 UT southward turning of the interplanetary magnetic field (IMF), the plasmasphere on both nightside and dayside surged sunward, reducing the plasmasphere radius on the nightside and creating a broad drainage plume on the dayside. Over several hours this plume narrowed in magnetic local time (MLT), until shortly after a northward IMF turning between 1430 UT and 1500 UT, when the plume began corotating with the Earth. On a global scale, the 18 June EUV plasmasphere observations are consistent with the interpretation that dayside magnetopause reconnection (DMR) during southward IMF produced a sunward convection field in the inner magnetosphere. Using the Volland-Stern electric potential model normalized to the solar wind E-field, we performed a simple plasmapause test particle (PTP) simulation of the 18 June event and found good global agreement with EUV observations, but important sub-global differences as well. On a sub-global scale, proper treatment of plasmaspheric dynamics requires consideration of subauroral polarization streams (SAPS) and penetration electric field to explain narrow duskside plumes and preferential pre-dawn plasmapause motion, respectively. The 18 June 2001 EUV images contain evidence of a double plume (or bifurcation of a single plume) and dayside crenulations of the plasmapause, both of which remain unexplained. The observations suggest that strong convection suppresses or smooths plasmapause structure, which tends to increase during times of weak or absent convection. Analysis of the motion of the plasmapause on 18 June 2001 reveals some of the details of the initial erosion process, which apparently involves partial indentation of the plasmapause and subsequent widening of this indentation to other MLT sectors eastward and westward of the initial indentation, and produces Ôrotated VÕ signatures in the electric field. Early erosion on 18 June was bursty, and modulated by the solar wind electric field; convection was turned on during southward IMF and turned off during northward IMF. Northward IMF apparently triggered overshielding, causing the formation of a midnight-to dawn plasmapause bulge that subsequently corotated. It is clear that more detailed information about the inner magnetospheric E-field is required to fully understand plasmaspheric dynamics. _______________ in "Global Physics of the Coupled Inner Magnetosphere", Proceedings of 2004 Yosemite Workshop, M. Schulz, H. Spence, and J. L. Burch, eds., American Geophysical Union, Washington, D. C., in press, doi:10.1029/2004BK000104, 2005.