Stability of the high-Latitude reconnection site for steady northward IMF

The stability of the high-latitude reconnection site under steady northward Interplanetary Magnetic Field (IMF) conditions was investigated using observations in the Earth's magnetospheric cusp. Using proton distributions with characteristic low-energy cutoffs, the distance to the high-latitude reconnection site was monitored during four cusp crossings that had relatively steady solar wind dynamic pressure and IMF clock angle, For these four events, the reconnection site location remained approximately fixed, indicating that the high-latitude magnetic reconnection site remains stable for many minutes under steady IMF conditions. A-possible explanation for this stability is that the magnetosheath flow remains sub-Alfvenic even at high latitudes because of the presence of a plasma depletion layer.