Use of Fe charge state changes as a tracer for solar wind entry to the magnetosphere

We present a comparison of high charge state ion composition measurements from ACE located near the L1 point and POLAR in the mid-altitude cusp/cleft, during the 1-3 May 1998 CME event. Using the frozen in charge state of the solar wind origin Fe ions as a tracer, we demonstrate the connectivity between the ACE observations and the high latitude measurements from POLAR. The ion charge state distributions were observed to show abrupt changes with variations in the average charge state of Fe between +6 and +15 corresponding to changes in the coronal source temperature of 4x10⁵ to 2x10⁶ K. A good correlation between the measurements at L1 and in the cusp/cleft was found, indicating direct entry of solar wind material during periods of southward IMF. In addition there is possible evidence for delayed entry during a period of predominantly northward IMF that may indicate a less direct entry mechanism for this configuration.